Working Off-Grid Efficiently(100r.co)
100r.co
Working Off-Grid Efficiently
https://100r.co/site/working_offgrid_efficiently.html
142 comments
Bonus points from developing on slow hardware: you really have to code efficiently, as you notice, when something is going wrong and takes more time, than it should
Also I now like the combination of computer with pen and paper. So sketching design things or algorithms on paper, before implementing them as code. (started doing so, to save batterie)
Also I now like the combination of computer with pen and paper. So sketching design things or algorithms on paper, before implementing them as code. (started doing so, to save batterie)
If you don't mind me asking, which Chromebook do you have and how much coding do you get out of the 1 panel/2.5kg trips between charges?
I also use devtools and node. I would love to find a device that focuses on low power consumption. I wish I could find something like this, but with a larger screen, usb charging, and ideally a single unit.
http://blog.yarm.is/kindleberry-pi-zero-w.html
I also use devtools and node. I would love to find a device that focuses on low power consumption. I wish I could find something like this, but with a larger screen, usb charging, and ideally a single unit.
http://blog.yarm.is/kindleberry-pi-zero-w.html
The pi 400[0] sounds pretty close to what you're afer, sans screen though.
[0]: https://arstechnica.com/gadgets/2020/11/raspberry-pi-400-the...
[0]: https://arstechnica.com/gadgets/2020/11/raspberry-pi-400-the...
I have a Asus C213. I think C214 is the current version.
I really love the hardware. It is indeed rugged and water resistant, it had to endure much on my travels, fell down a lot or things on it. Moisture, sand, heat, ice and snow - and is also made for maintaineance, I could quite easily replace the touchscreen, the only thing that broke, which was really my fault for stepping on it (but getting the replacement part, I had to order from china)
And how much coding I get out if it, well depends on the situation. If there is strong sun all the time, then forever. Also with just 1 panel and batterie.
The batterie on its own last 10+ hours (now after 4 years of intense use obviously not anymore)
Meaning if you code during the day, your power bank gets charged in the meantime. Can get charged full from empty in the right conditions in some hours and one power bank gives me around 1.5 laptop, charges. More power than you need.
Meaning just with 1 extra batterie I get 25 hs of coding. Meaning on short trips of limited time and unstable sun, I just bring a second power bank and have 40 h of work without needing to recharge.
But since the sun does not shine all the time and I spend weeks and at times, months off the grid, I upgraded to 2 panels and 3 batteries to really not care about power anymore.
Before I learned to be energy efficient. Which also lead to interesting results, like I only opened up the lid, if I really knew what to do. So intense short burst of coding and then stop and thinking about the next step, or the current problem, that showed up. It is efficient and also healthy, giving your eyes only limited screen exposure with lots of rest, but still getting stuff done.
edit: about device, before that one I had a cheap windows convertible. For 200 € you get already 10+h of work, lightweight and USB charging. But I really can't stand windows. And stock linux drivers are too buggy in that segment. When I open up my chromebook, it is immediately awake and I can resume exactly where I closed it. On my bigger powered manjaro laptop, I have to wait at least 10 seconds, which disturbs my flow.
I really love the hardware. It is indeed rugged and water resistant, it had to endure much on my travels, fell down a lot or things on it. Moisture, sand, heat, ice and snow - and is also made for maintaineance, I could quite easily replace the touchscreen, the only thing that broke, which was really my fault for stepping on it (but getting the replacement part, I had to order from china)
And how much coding I get out if it, well depends on the situation. If there is strong sun all the time, then forever. Also with just 1 panel and batterie.
The batterie on its own last 10+ hours (now after 4 years of intense use obviously not anymore)
Meaning if you code during the day, your power bank gets charged in the meantime. Can get charged full from empty in the right conditions in some hours and one power bank gives me around 1.5 laptop, charges. More power than you need.
Meaning just with 1 extra batterie I get 25 hs of coding. Meaning on short trips of limited time and unstable sun, I just bring a second power bank and have 40 h of work without needing to recharge.
But since the sun does not shine all the time and I spend weeks and at times, months off the grid, I upgraded to 2 panels and 3 batteries to really not care about power anymore.
Before I learned to be energy efficient. Which also lead to interesting results, like I only opened up the lid, if I really knew what to do. So intense short burst of coding and then stop and thinking about the next step, or the current problem, that showed up. It is efficient and also healthy, giving your eyes only limited screen exposure with lots of rest, but still getting stuff done.
edit: about device, before that one I had a cheap windows convertible. For 200 € you get already 10+h of work, lightweight and USB charging. But I really can't stand windows. And stock linux drivers are too buggy in that segment. When I open up my chromebook, it is immediately awake and I can resume exactly where I closed it. On my bigger powered manjaro laptop, I have to wait at least 10 seconds, which disturbs my flow.
How do you manage(d) working with npm modules?
My chromebook is in dev mode, so I can use chromebrew and just install npm.
But I just use and do not create npm packages, so I don't know if theres a limitation there.
(in theory I could boot a full linux in embedded VM, but that is too ressource intensive for my taste)
In general, ChromeOS sucks, but the driver and firmware is really optimated, which means fast sleep/wakeup and long batterie life and with my basic tools running I am quite happy, even though my control over the system is much restrained compared to my manjaro laptop for example.
(in theory I could boot a full linux in embedded VM, but that is too ressource intensive for my taste)
In general, ChromeOS sucks, but the driver and firmware is really optimated, which means fast sleep/wakeup and long batterie life and with my basic tools running I am quite happy, even though my control over the system is much restrained compared to my manjaro laptop for example.
I run my “office” on portable solar much of the summer. Two takeaways:
Solar averages ~10W/m^2 long term (days/weeks) with wild fluctuations. Getting easy reliable output retirees a lot of surface & batteries.
When those storage batteries deplete, it’s a hard stop. Recharging takes considerable time, competing for scheduled direct use. Plan on at least doubling panel surface just to recover from outages, and plan on more storage than you expect because long uncooperative weather happens more often, with more consequences, than you expect.
Unless you are willing to shut down completely at times, or spend enormous sums, you must have a reliable on-grid source ... which then may as well be your primary.
Solar averages ~10W/m^2 long term (days/weeks) with wild fluctuations. Getting easy reliable output retirees a lot of surface & batteries.
When those storage batteries deplete, it’s a hard stop. Recharging takes considerable time, competing for scheduled direct use. Plan on at least doubling panel surface just to recover from outages, and plan on more storage than you expect because long uncooperative weather happens more often, with more consequences, than you expect.
Unless you are willing to shut down completely at times, or spend enormous sums, you must have a reliable on-grid source ... which then may as well be your primary.
A reliable, secondary source of power to account for consecutive days of bad weather doesn't need to be "on-grid."
Most robust off grid setups that I've seen involve the use of a backup generator.
For anyone considering an off grid mobile office in a van or other vehicle. When the sun isn't cooperative for too long and I find my storage battery being depleted too low, I simply start my engine and start charging the battery using my 12V DC cigarette lighter port.
I have 200W of solar feeding a 100Ah 12V battery with an MPPT charge controller and I thought I had calculated enough redundancy to handle up to a week of bad weather, but end up using my alternator to charge when the sun is unreliable more often than I thought I would.
PS: Are you using a PWM controller or a MPPT controller? The latter can increase efficiency by up to 30%.
Most robust off grid setups that I've seen involve the use of a backup generator.
For anyone considering an off grid mobile office in a van or other vehicle. When the sun isn't cooperative for too long and I find my storage battery being depleted too low, I simply start my engine and start charging the battery using my 12V DC cigarette lighter port.
I have 200W of solar feeding a 100Ah 12V battery with an MPPT charge controller and I thought I had calculated enough redundancy to handle up to a week of bad weather, but end up using my alternator to charge when the sun is unreliable more often than I thought I would.
PS: Are you using a PWM controller or a MPPT controller? The latter can increase efficiency by up to 30%.
> Solar averages ~10W/m^2 long term (days/weeks)
That figure surprises me. What I’ve heard before is that full sun is roughly 1kW/m², and that over time you should expect to get 4–5 useful hours (depending on latitude and weather conditions of where you are—some will be outside this range on either side), so if you take 21% efficient solar panels, the total would be 1000 (watts) × 4 (hours) / 24 (hours) × 0.21 (efficiency) = 35W.
10W is a lot less than 35W. I presume I have some incorrect assumption or am overlooking something.
(I’m interested in this because I’m planning to build a velomobile and live out of it while going round Australia for a year. Power systems are something I’ve been putting a fair bit of theoretical research into, but I have no practical experience whatsoever. I’ve been planning to build solar panelling into the body.)
That figure surprises me. What I’ve heard before is that full sun is roughly 1kW/m², and that over time you should expect to get 4–5 useful hours (depending on latitude and weather conditions of where you are—some will be outside this range on either side), so if you take 21% efficient solar panels, the total would be 1000 (watts) × 4 (hours) / 24 (hours) × 0.21 (efficiency) = 35W.
10W is a lot less than 35W. I presume I have some incorrect assumption or am overlooking something.
(I’m interested in this because I’m planning to build a velomobile and live out of it while going round Australia for a year. Power systems are something I’ve been putting a fair bit of theoretical research into, but I have no practical experience whatsoever. I’ve been planning to build solar panelling into the body.)
35 is pretty close to 10 when you start at 1300 and prune obstructions.
Now address clouds, angles, dust, snow, opacity, malfunctions, storage inefficiencies, panel aging, and chronic optimism. 10W.
Now address clouds, angles, dust, snow, opacity, malfunctions, storage inefficiencies, panel aging, and chronic optimism. 10W.
Most of that is what the 4–5 useful hours per day figure is supposed to take care of (that’s a year-round thing, too, averaging summer, which may be as much as double that, and winter, which may be half).
Hmm… storage inefficiencies? Are you including battery storage and perhaps an inverter in your calculations? I guess that’d account for some loss.
I’m guessing also from “snow” that you may be in a place that gets comparatively little sunlight?
Hmm… storage inefficiencies? Are you including battery storage and perhaps an inverter in your calculations? I guess that’d account for some loss.
I’m guessing also from “snow” that you may be in a place that gets comparatively little sunlight?
42,339 MW of PV installations produced 39,401 GWh of energy in 2017 in Germany[1], so about 38 days of peak generation, or roughly 10.5% of peak. A square meter of PV panels produces around 150W. So 15W average for a panel in a good location in Germany. 10W/m^2 seems like a good estimate if you want your stuff to work reliably year round. Better locations than Germany would do better of course, and restricting yourself to just summer probably helps quite a bit too (winters are dark and cloudy in Germany).
[1] https://en.wikipedia.org/wiki/Solar_power_in_Germany#Statist...
[1] https://en.wikipedia.org/wiki/Solar_power_in_Germany#Statist...
Germany is north of Maine, it’s a terrible location for solar power and heavily subsidized. At best they hit a capacity factor of 11.6% in 2018. By comparison the US had a capacity factor of 28% for utility-sized PV plants in 2015, but it’s dropped as less efficient locations have been added.
A square meter of PV panels produces around 150W, that’s some low efficiency panels, you can easily hit 200+W/M2 using a high efficiency panel like SunPower Maxeon 3.
Solar isn’t a great fit everywhere. So, people really can see wildly different outputs from the same setup based on location. At 28% capacity factor averaging 60+W/M is very possible.
A square meter of PV panels produces around 150W, that’s some low efficiency panels, you can easily hit 200+W/M2 using a high efficiency panel like SunPower Maxeon 3.
Solar isn’t a great fit everywhere. So, people really can see wildly different outputs from the same setup based on location. At 28% capacity factor averaging 60+W/M is very possible.
Thanks for the reference to the 200W panel!
I wonder if "4-5 useful hours per day" is per sunny day, so you can cut your number in half again for cloudy days.
No, this is from averaging it across the entire year, based mostly on locations in the south of Australia (Gippsland, Melbourne, Adelaide, Ballarat, those sorts of areas), but I looked briefly at other parts of the world also. The idea is then that a panel rated at 250W can produce an average of about 1kWh per day when pointed in the optimal direction and never shaded (but without tracking the sun); the average winter day may get you only 500W, and the average summer day over 1500W, with plenty of variation within those seasons day by day also.
The most shocking thing I ever learned about solar panels is that they behave as a rectifying diode when they are not receiving sufficient photons.
That means you can screw up the current from an entire bank of solar panels by having just one of them in deep shade. So if you want maximum generation, you either have to site them in a very clear area, or wire them all in parallel instead of serial, which means much fatter wires to reduce transmission losses, and then larger conversion losses?
That means you can screw up the current from an entire bank of solar panels by having just one of them in deep shade. So if you want maximum generation, you either have to site them in a very clear area, or wire them all in parallel instead of serial, which means much fatter wires to reduce transmission losses, and then larger conversion losses?
One way around this is to utilize cheap micro-inverters on each panel. This makes it easier to add new panels as your usage goes up (or funds). Also easier to monitor their performance due to shading, dust, etc.
I don't think this is the case with newer panels. Our boat stern mounted panels atleast had one panel shaded at anytime. The output drop was proportional to the area shaded. The bigger losses came from the angle of the sun. Output was mostly logarithmic, almost nothing at sunrise/sunset, full output at 12pm, 50% by 3pm.
It's still true of the cells in the panels. But it's typical these days to add a device between the panels and the DC circuit than can improve the situation (e.g. by cutting the panel out of the circuit if it isn't productively contributing the array's generating capacity at the moment).
So the problem should be corrected at the panel level, but still exists at the cell level?
Yes, the diode behavior is (I believe) a fundamental property of the cells.
I'm not sure on the details, but according to my solar installer newer panels (or inverters or some other component) are no longer susceptible to this.
The key term with this is bypass diodes. Not all panels will be equipped with them (which puzzles me, given the substantial benefit and what I imagine to be near-trivial BOM cost).
I learned this at the Exploratorium in SF. They had an exhibit consisting of a miniature solar panel with an output reading and a small token that could cover a single panel. Very fun trip!
I remember back in 1989 or so(!), my mom used to work at our summer cabin which had no electricity using a ~1m^2 solar panel, hooked up directly to a car battery, which was hooked up to a small laptop (a Compaq, I think).
I have no idea if such a setup would be remotely feasible today.
I have no idea if such a setup would be remotely feasible today.
Oh, it’s feasible. That’s close to what I’m fiddling with (just GoalZero.com products instead of bare car batteries etc). It’s quite workable, but you have to be keenly aware of usage & limitations, and fiddle with stuff often (ex.: coping with passing shadows). Most people are expecting complete reliability - that’s costly.
Panels are better, MPPT are cheaper, and the right laptop uses hardly any power... I would think it should be more feasible in every possible way aside from increased expectations.
A Surface Go averages something like 5W, and a 100W array can provide that in virtually all daytime conditions even without aiming.
A Surface Go averages something like 5W, and a 100W array can provide that in virtually all daytime conditions even without aiming.
Additionally, the right laptop can use its internal voltage regulator to convert the 12-16 volts from the battery into the internal voltage.
One of the secrets of the openwrt community was that those little linksys routers used a 9v power brick but the power regulator was still stable somewhere north of 12v, giving you a lot more options for repeaters or mesh networking.
One of the secrets of the openwrt community was that those little linksys routers used a 9v power brick but the power regulator was still stable somewhere north of 12v, giving you a lot more options for repeaters or mesh networking.
12V DC 0.5A was typical, stable from 5-30V depending on the exact model.
> you must have a reliable on-grid source ... which then may as well be your primary.
Not at all.
With net metering it makes sense to be on the grid during the day when you're making more power than you need, then if and when you need it you can pull power from the grid.
In Australia my Dad got a 5kW system fully installed for $5k AUD, and he gets paid a few hundred dollars from the power company every three months now.
Not at all.
With net metering it makes sense to be on the grid during the day when you're making more power than you need, then if and when you need it you can pull power from the grid.
In Australia my Dad got a 5kW system fully installed for $5k AUD, and he gets paid a few hundred dollars from the power company every three months now.
Problem there is, with enough customers doing the same, there’s a great deal of idle capacity waiting to fill the big gaps. That’s costly. Works fine now when solar is the anomaly (what I’m doing, plugging into grid when a prolonged storm depletes stored power), but keeping 100% of current grid capacity in unused reserve for 1% incidents (heavy clouds for >1 weeks) isn’t practical. At some tipping point, classic grid power is driven out of the market ... and then an anomaly hits, with no grid to back into.
They are still saving fuel, and with weather forecasts they are not 'anomalies', they are planned handovers. You just need to work out the financials.
You could supplement with your own generator. Do you consider fuel to be an enormous sum, relative to solar?
I’m focusing on solar-only solutions.
Once you introduce sourcing as cheap & reliable as fossil fuels back into the equations, dropping solar entirely becomes a rational solution as the frequency of solar “incidents” becomes apparent and non-FF mitigation costs soar. I find most people don’t grasp how unreliable solar is.
Once you introduce sourcing as cheap & reliable as fossil fuels back into the equations, dropping solar entirely becomes a rational solution as the frequency of solar “incidents” becomes apparent and non-FF mitigation costs soar. I find most people don’t grasp how unreliable solar is.
Small-scale alcohol fuel production is an option. Grow sugar beets and make moonshine. It's still solar power. (No pun intended.) The molecules of alcohol are made of air and water and power from the sun.
Where do you live ?
You are making very bold claims about solar being unreliable, but I'd completely expect reliability of solar to vary significant from one location to another.
You are making very bold claims about solar being unreliable, but I'd completely expect reliability of solar to vary significant from one location to another.
Southeast USA. On the whole a good place for solar. I’m trying to impress on people the many fiddly little obstructions that add up to significant reductions, and that despite prolonged good periods there are poor exposure times that fast burn thru stored energy and require substantial collectors to recharge in time for the next weather event.
If you're intent on using solar anyway then I don't see how having a fallback generator would compel you to just give up on the solar. How often do you have to repair or replace panels?
It’s just plain easier & cheaper to run FFs than solar. About the only serious disadvantage is noise.
This is very misguided - anyone in serious remote area operates renewables with FF backup, because FF is expensive and delivery difficult and unreliable. If you ever been to remote lighthouse or similar, youd realise logitistics in delivering tonns of FF is not something you can take for grantes.
Those 200 KG of solar panels will save you many metric tons of oil over their lifetime
Those 200 KG of solar panels will save you many metric tons of oil over their lifetime
Not qualified to comment on any technical aspect of this. But this observation:
> "Living and working aboard a sailboat was for us a constraint, it liberated our imagination by eliminating possibilities."
Rings very true to me. When you're in a tent in the woods, without mobile internet and just human company for "entertainment", it's incredible how easy it is to have long conversations or to think/make up games to pass the time.
> "Living and working aboard a sailboat was for us a constraint, it liberated our imagination by eliminating possibilities."
Rings very true to me. When you're in a tent in the woods, without mobile internet and just human company for "entertainment", it's incredible how easy it is to have long conversations or to think/make up games to pass the time.
Indeed. I've had the good fortune to pass long periods of time (from days to months) hiking and it's amazing what entertainment just meeting a new person after weeks can provide. And no matter what book you bring along, you will finish it in a couple days without constant distraction.
I've been living mostly off grid for the past 3.5 years in a bus I converted. Solar isn't expensive anymore, panels can be had for <$1/Wh. The cost of batteries is still significant but some of that can be mitigated by buying used packs for 1/4 the price.
The key with being off grid is redundancy. One is none and two is one. For example, if there are storms that last a week you'll get almost no solar power. You need another way to get power, typically a fuel-based generator.
The key with being off grid is redundancy. One is none and two is one. For example, if there are storms that last a week you'll get almost no solar power. You need another way to get power, typically a fuel-based generator.
And you need to ventilate and supply that generator like it'll be running all the time.
See also winter storms, where going outside is a lot more problematic than just getting wet.
See also winter storms, where going outside is a lot more problematic than just getting wet.
Interesting article, but the extreme lack of electricity seems unnecessary, at least today. Solar panels have gotten much cheaper, enough so that generating adequate power to run a couple of laptops even on cloudy days is fairly affordable. Batteries to keep it going at night have also come down in price.
Maybe the extreme power savings are more of an aesthetic thing for them.
Maybe the extreme power savings are more of an aesthetic thing for them.
On a medium sized sailboat the limiting factor for how much PV capacity you can have is the physical mounting space. Google "bimini top solar panel":
https://www.google.com/search?q=bimini+top+solar+panel&clien...
What could be trivially easy to mount on a small off grid cabin in the woods somewhere, like two of these:
https://www.altestore.com/store/solar-panels/panasonic-hit-h...
could be very difficult and too much surface area and wind loading on a sailboat that people can realistically afford to buy. If you have the space and can fit one, something like the Sunpower 400W rated panels which are composed of expensive, ultra high efficiency monocrystalline Si cells would be ideal. You're looking for the greatest ratio of watts per square meter in STC test conditions.
What I would recommend is first calculating the watt-hours per day consumed by your projected load, versus what the PV system could be expected to produce.
https://www.google.com/search?q=bimini+top+solar+panel&clien...
What could be trivially easy to mount on a small off grid cabin in the woods somewhere, like two of these:
https://www.altestore.com/store/solar-panels/panasonic-hit-h...
could be very difficult and too much surface area and wind loading on a sailboat that people can realistically afford to buy. If you have the space and can fit one, something like the Sunpower 400W rated panels which are composed of expensive, ultra high efficiency monocrystalline Si cells would be ideal. You're looking for the greatest ratio of watts per square meter in STC test conditions.
What I would recommend is first calculating the watt-hours per day consumed by your projected load, versus what the PV system could be expected to produce.
Another factor in sail boats is the shading caused by masts, stowed sails, hand rails and lines. It's one of the few places where micro-scale wind turbines almost work.
Sort of... but the wind turbines often don't point well when you're at sea, and you intentionally anchor in calm places to avoid the swell.
Sailing specific PV would often have 40 silicon cells rather than 36 in series, to provide some headroom for partial shading.
Watt & sea hydro-generators have become quite ubiquitous recently, as if you're making passage your entire vessel is a machine for concentrating wind energy: https://www.wattandsea.com/index.php/en/products/cruising-hy...
Also you may be more likely to stay put on a calm day, increasing demand for power.
I'm clueless in this area. Would a raft be viable? Presumably it would add some drag if you're underway but a small inflatable pontoon raft seems like it could run 4-6 panels and be reasonably portable when not in use.
I do off grid PV professionally but don't know a lot about boats. But having been on a few 42-48 ft size cruiser type sailboats, I can't think of a place you could easily pack away six 1.65x1.0 meter size (typical 60-cell) rigid, aluminum framed high efficiency PV panels, unless you basically dedicated the smaller guest bunk to storage space.
Hey. You said you do off grid. I have a question. I own a 5 kW on grid setup for net metering. Works fine but now I want to use backups. I have two options,
either lithium 100ah 48v which is expensive or 12v 200ah x 4 to make 48v. Cheaper but limited life because the home load would be on it entirely.
I dont know. The calculation of kWh checks out to be 100ah x 48v = 4800wh. And for lead acid 200ah x 12v x 2= 4800wh.
What do you suggest or is there something I am thinking incorrectly... space is not an issue BTW.
I dont know. The calculation of kWh checks out to be 100ah x 48v = 4800wh. And for lead acid 200ah x 12v x 2= 4800wh.
What do you suggest or is there something I am thinking incorrectly... space is not an issue BTW.
google "DIY powerwall" if you're up for a bit of a technical challenge.
4 x 12V 200Ah isn't big enough for most houses, unless it's like a cabin in the woods somewhere. and you're right that the cycle life of those and cost is high.
but commercial li-ion based solutions are also expensive. However, if you can keep them at 80-85% state of charge, and rarely if ever discharge them below 30%, they should have lifespans 5-6x longer than the lead acid solution.
in either solution you can't really consider the full volts * Ah capacity of the battery to be usable. If you were to ever use all of the watt-hours in a 12V 200Ah battery you'd kill it, you never want to go below 20% state of charge... so to be conservative the actual capacity of a single battery is something like:
12 * 200 = 2400 Wh, then (2400 * 0.70) = 1680Wh.
4 x 12V 200Ah isn't big enough for most houses, unless it's like a cabin in the woods somewhere. and you're right that the cycle life of those and cost is high.
but commercial li-ion based solutions are also expensive. However, if you can keep them at 80-85% state of charge, and rarely if ever discharge them below 30%, they should have lifespans 5-6x longer than the lead acid solution.
in either solution you can't really consider the full volts * Ah capacity of the battery to be usable. If you were to ever use all of the watt-hours in a 12V 200Ah battery you'd kill it, you never want to go below 20% state of charge... so to be conservative the actual capacity of a single battery is something like:
12 * 200 = 2400 Wh, then (2400 * 0.70) = 1680Wh.
Current LFP battery prices are around $120 per kWh delivered: I just ordered 14 kWh (48V 16S) for 1700 USD delivered.
This is cheaper than an Apple laptop.
A quarter of the price paid is shipping since it comes directly from China so source price is already under $100/kWh.
A recent test by Will Prowse:
https://www.youtube.com/watch?v=3U4ZfQ_IToI
$433 280Ah LiFePO4 Cells Tested: Cheaper than lead acid!
Many people have the same good experience with these kind of cells:
https://diysolarforum.com/
Added: 14 kWh will run a 20 Watt laptop for a month.
This is cheaper than an Apple laptop.
A quarter of the price paid is shipping since it comes directly from China so source price is already under $100/kWh.
A recent test by Will Prowse:
https://www.youtube.com/watch?v=3U4ZfQ_IToI
$433 280Ah LiFePO4 Cells Tested: Cheaper than lead acid!
Many people have the same good experience with these kind of cells:
https://diysolarforum.com/
Added: 14 kWh will run a 20 Watt laptop for a month.
The part in that youtube video where he's using uninsulated steel wrenches across the top bus bars to tighten down the terminals is extremely scary.
I don't think there is a huge risk when you're dealing with 12V batteries.
Where are you getting new LFP batteries for that price?
There is a fellow down in Port St. Lucie Florida that has launched a 100ah LiFePO4 with a 10-year warranty for ~ $550usd each. I saw his shop in person when I purchased some solar from him and was quite impressed with the work they've done and the research and testing that has gone into their products. I had already purchased my batteries by the time I discovered his product or I would have purchased from him: https://outlandsolar.com/
My partner and I live aboard a 41ft sailboat and both work remotely as programmers. I installed 1920w of solar on the boat and get approximately 3.5-4.5kwh per day in output, depending on which way we are oriented while at anchor. I installed 600ah of LiFePO4 batteries @ 12v and when combined with that amount of solar, we have pretty much all the power we need. We frequently cook with an air fryer and have a dishwasher on the boat that we run daily-- all off solar.
My partner and I live aboard a 41ft sailboat and both work remotely as programmers. I installed 1920w of solar on the boat and get approximately 3.5-4.5kwh per day in output, depending on which way we are oriented while at anchor. I installed 600ah of LiFePO4 batteries @ 12v and when combined with that amount of solar, we have pretty much all the power we need. We frequently cook with an air fryer and have a dishwasher on the boat that we run daily-- all off solar.
Where/how do you fit ~2000W of solar on your boat? That’s impressive.
I ended up mounting two ~39x70in panels on top of the davits and one on each side of the stern, mounted to the stanchions like 'wings' that can be propped up while at anchor. Strangely enough, I found I was getting so much power from the panels that I don't bother propping them up. Because of the way the panels are mounted (basically at least 1 panel facing the sun at all times), I'm able to get roughly 500w from 8:30am until just after 5pm. I was pleasantly surprised.
SOK Battery also has an 100ah battery for $570. They look a little more reputable then a DIY'er, but kudos to him for selling. a product.
Will prowse has a link to the vendor he chose in the youtube video description, if you search for "supplier" in the forum you'll get plenty of feedback on various known vendors.
I chose one (after sending a few private message to forum members) but I'm not recommanding it until I get and test my batteries.
I chose one (after sending a few private message to forum members) but I'm not recommanding it until I get and test my batteries.
My dad gave me Will Prowse's book as a resource when I was rigging my van with solar - it was a great read but not a necessary buy because all the info you need is on his website.[0] His YouTube channel is a great resource that I'd definitely recommend! Interested to hear what the brand is if your tests turn out satisfactory.
[0] https://www.mobile-solarpower.com/
[0] https://www.mobile-solarpower.com/
Beware of suspiciously cheap lifepo4 batteries from China, they are by no means all the same.
If you look for known good chinese LFP vendors on forums it minimize the risk, lots of people are reporting to spec or very close to spec batteries. And when they are issues looks like most chinese vendors will just send a replacement if you document your problem well (compare this to local store return processes ...).
But LFP batteries have gotten really cheap, so the price for a mistake is no longer prohibitive.
But LFP batteries have gotten really cheap, so the price for a mistake is no longer prohibitive.
The high efficiency panels are typically semi-flexible without the frame, are they not? Do you think it would be possible to obtain and mount them without a rigid frame? Or even to remove them from the frame? I'm asking partly because I had considered making some sort of basic, folding, portable solar panel structure- imagine a few semi-flexible panels duct-taped together. (I'd likely not _actually_ use duct tape).
That's backwards. Flexible panels are less efficient than rigid ones.
Correct, flexible cells are 10-14% efficient, the best rigid monocrystalline single junction Si cells are 23% plus.
I think that's correct for thin film panels. But it appears that monocrystalline panels can be manufactured with some flexibility. Hence my usage of the term "semi-flexible". Sunpower, for example, claims to produce high efficiency semi-flexible monocrystalline panels that would flex sufficiently for use on a bimini top, for example.
It further appears that my statement "high efficiency panels are typically semi-flexible without the frame" is inaccurate- they are typically not reasonably described as semi-flexible, even without the frame and coating.
It further appears that my statement "high efficiency panels are typically semi-flexible without the frame" is inaccurate- they are typically not reasonably described as semi-flexible, even without the frame and coating.
Real high efficiency monocrystalline si cells are not flexible in any way, for example the typical 156mm cell that makes up a 315-400W rated 60 or 72 cell panel. In fact they're quite brittle and fragile when not encapsulated on a backing sheet and under protective glass.
Monocrystalline by definition is not flexible, you're referring to thin films (cadmium telluride or amorphous silicon or other)
Monocrystalline by definition is not flexible, you're referring to thin films (cadmium telluride or amorphous silicon or other)
Thanks for the reply.
Is there any middle ground?
Is Sunpower's claim of 22-25% efficient monocrystalline semi-flexible panels not to be believed? Have I been fooled by the marketing? Are these thin film panels? Nothing I can find online suggests this is a dubious claim, but it's possible I'm simply failing to find correct information.
Is there any middle ground?
Is Sunpower's claim of 22-25% efficient monocrystalline semi-flexible panels not to be believed? Have I been fooled by the marketing? Are these thin film panels? Nothing I can find online suggests this is a dubious claim, but it's possible I'm simply failing to find correct information.
Why not floating solar panels attached to the boat?
(Just a random idea, I know absolutely nothing about boats :)
(Just a random idea, I know absolutely nothing about boats :)
One of my favorite science-fictions was imagining the Sea Slice, repurposed as a deployable floating mini-solar power plant. To actually be able to get anywhere, you'd need a gobsmackingly large amount of power storage, or you just take it day by day, charge for a couple hours, go, charge for a couple hours, go.
Sure wish I had a million dollars sitting around when the ship went on sale for $280k. And a couple more friends with free time & well-equipped workshops.
https://www.thedrive.com/the-war-zone/29428/the-experimental...
Sure wish I had a million dollars sitting around when the ship went on sale for $280k. And a couple more friends with free time & well-equipped workshops.
https://www.thedrive.com/the-war-zone/29428/the-experimental...
When you're docked in a marina or similar its unlikely there would be space.
When you're sailing or motoring somewhere you want the minimum drag\resistance through the water, and more importantly, the waves would smash them to pieces in no time. To make them weatherproof would mean making them less like a floating solar panel and more like a small boat.
> Solar panels have gotten much cheaper, enough so that generating adequate power to run a couple of laptops even on cloudy days is fairly affordable. Batteries to keep it going at night have also come down in price.
From the article:
> Our work schedule is tied to the weather, as we depend on solar energy to power our computers.
So, what's the problem then? Well, they've written in-depth about the challenges and constraints of solar elsewhere on the site. [1]
Their vessel is on the smaller side of the spectrum. There's only so much usable space to place a solar array. [2] They do use batteries and they have a small gas generator, but those are also limited and only used as a backup.
[1] https://100r.co/site/off_the_grid.html#power [2] https://100r.co/site/pino.html
From the article:
> Our work schedule is tied to the weather, as we depend on solar energy to power our computers.
So, what's the problem then? Well, they've written in-depth about the challenges and constraints of solar elsewhere on the site. [1]
Their vessel is on the smaller side of the spectrum. There's only so much usable space to place a solar array. [2] They do use batteries and they have a small gas generator, but those are also limited and only used as a backup.
[1] https://100r.co/site/off_the_grid.html#power [2] https://100r.co/site/pino.html
I'm trying to run a company in a hostile regulatory environment. I've been without power since April 2020.
This is in the middle of a city in the United States.
I've tried generators and have gone through 3 so far. Fuel was very expensive, and the time and effort to keep them running 24/7 was miserable. I have now tried going solar but have had all sorts of problems with battery life and cloudy weather. It's not as easy as I thought it would be.
This is in the middle of a city in the United States.
I've tried generators and have gone through 3 so far. Fuel was very expensive, and the time and effort to keep them running 24/7 was miserable. I have now tried going solar but have had all sorts of problems with battery life and cloudy weather. It's not as easy as I thought it would be.
> I'm trying to run a company in a hostile regulatory environment. I've been without power since April 2020. This is in the middle of a city in the United States.
.. how? Which city?
.. how? Which city?
There might be a relevant distinction between "without power" and "power is not available to me".
The city won't approve the electrical hookup to the building I purchased. I've had 2 different commercial contractors try to pull permits and both of them were denied. Not denied in writing, but convinced not to file the required application. I was actually assaulted by a zoning officer while sitting in their office trying to fill out an application they didn't want me to submit.
That sounds miserable. Fighting (an office of) City Hall is a painful experience.
You must have some idea of why they are obstructing though, right? An electrical permit is an indirect block, so I'm guessing you've fought other battles with the office in the past?
In any case, you have a right to file the permit. The office might make your life hell through documented denials or overzealous inspections, but getting the permit filed should be non-controversial. Once filed, they must approve or deny. If denied, there is a formal appeals process which can run through different people/departments. If you have the time and energy for it, of course.
Anyway, I know you are not here soliciting advice, but my next step would be to bring a lawyer to the filing office to ensure that the application is filed, and that no further assault occurs. Good luck.
You must have some idea of why they are obstructing though, right? An electrical permit is an indirect block, so I'm guessing you've fought other battles with the office in the past?
In any case, you have a right to file the permit. The office might make your life hell through documented denials or overzealous inspections, but getting the permit filed should be non-controversial. Once filed, they must approve or deny. If denied, there is a formal appeals process which can run through different people/departments. If you have the time and energy for it, of course.
Anyway, I know you are not here soliciting advice, but my next step would be to bring a lawyer to the filing office to ensure that the application is filed, and that no further assault occurs. Good luck.
I called a lawyer when the incident happened where I couldn't file the application.
I do feel like part of the problem is they don't actually want to give me anything in writing.
I've got a scheduled meeting with the mayor, my lawyer, the fire marshal, and the main zoning officer on the 21st of this month.
I do feel like part of the problem is they don't actually want to give me anything in writing.
I've got a scheduled meeting with the mayor, my lawyer, the fire marshal, and the main zoning officer on the 21st of this month.
> I do feel like part of the problem is they don't actually want to give me anything in writing.
That sounds like a reasonable guess to me.
If there is some personal animosity, or they have a friend who runs a potential competitor/lost on the purchase bid/etc, or somesuch other corrupt motivations ... then their only real power is to exhaust you.
Once you have a live permit application, you're in the system and the legal process takes over. They can still hit you hard on process and code conformity, but it takes greater coordination to do so.
Again, good luck. Petty corruption is sometimes the worst kind.
That sounds like a reasonable guess to me.
If there is some personal animosity, or they have a friend who runs a potential competitor/lost on the purchase bid/etc, or somesuch other corrupt motivations ... then their only real power is to exhaust you.
Once you have a live permit application, you're in the system and the legal process takes over. They can still hit you hard on process and code conformity, but it takes greater coordination to do so.
Again, good luck. Petty corruption is sometimes the worst kind.
I found out that they started a tax and allocated about $10M to doing the same things I'm trying to do. They've already put $400k into their business incubator, but it hasn't opened yet.
Their science museum kinda sucks, and their "maker space" is a laser cutter tacked onto the incubator as an afterthought.
The building I bought is 220,000 sqft and I'm passionate about doing all the things that tax is supposed to pay for, but I didn't know this at the time.
If I fail and nobody notices then everything is fine for them. But if I succeed, people might wonder what the tax went to if I don't get some of it, and I'm sure it's all already spoken for.
The thing is, I don't even care about that money. I just want to do my own thing without interference.
Their science museum kinda sucks, and their "maker space" is a laser cutter tacked onto the incubator as an afterthought.
The building I bought is 220,000 sqft and I'm passionate about doing all the things that tax is supposed to pay for, but I didn't know this at the time.
If I fail and nobody notices then everything is fine for them. But if I succeed, people might wonder what the tax went to if I don't get some of it, and I'm sure it's all already spoken for.
The thing is, I don't even care about that money. I just want to do my own thing without interference.
I'm sorry I misjudged you, that sounds miserable.
This almost sounds like someone whose nightclub has had to go DL to ignore covid restrictions.
Pine Bluff, Arkansas.
More than that, they're on a sailboat! Electric motors offer regen when under sailpower, which is absolutely huge, or you can get a towable torpedo generator. Otherwise, get a small wind turbine.
You can subsist on PV alone but there are far better options, especially when available PV area is so limited.
You can subsist on PV alone but there are far better options, especially when available PV area is so limited.
Congrats on reading the article and not getting the context.
They live on a boat, by the sea, often in the middle of the ocean.
Even with solar panel, extreme power saving is a necessity.
They live on a boat, by the sea, often in the middle of the ocean.
Even with solar panel, extreme power saving is a necessity.
If you found this interesting you will probably also enjoy having a read of Joey Hess' blog https://joeyh.name/offgrid/
Joey Hess is also the author of git-annex (https://git-annex.branchable.com/), which helps with some of the things mentioned in the "Internet" and "Data Storage" sections of this article.
I’ve been following Hundred Rabbits’ Rekka[1] and Devine[2] for a while. Their sites are full of interesting tidbits on different topics and projects. If you liked the article I recommend having a look at them.
[1]: https://kokorobot.ca/site/home.html
[2]: https://wiki.xxiivv.com/site/home.html
[1]: https://kokorobot.ca/site/home.html
[2]: https://wiki.xxiivv.com/site/home.html
What a beautiful website -- so inkeeping with their mission and ideas (this comes up quite often but, those dithered images really remind me of https://solar.lowtechmagazine.com/power.html)
It's pretty amazing that the article and the whole comment thread neglect OSes.
I use Debian with i3 on a 10 years old laptop with 4GB of RAM. It's my only workstation and I'm a software engineer.
I usually run two browsers including a tab for slack. Everything works fine.
Tip: install the documentation OS packages for all the libraries you need and also read manpages. Works well when you are on planes often and makes you a better developer than relying on search engines.
I use Debian with i3 on a 10 years old laptop with 4GB of RAM. It's my only workstation and I'm a software engineer.
I usually run two browsers including a tab for slack. Everything works fine.
Tip: install the documentation OS packages for all the libraries you need and also read manpages. Works well when you are on planes often and makes you a better developer than relying on search engines.
I'm not really sure I understand. Most modern laptops are much more power efficient than older models.
If you're really looking to save watts, and ARM chromebook is pretty hard to beat.
If you're really looking to save watts, and ARM chromebook is pretty hard to beat.
I'm providing an example on how efficient software can run on limited hardware resources.
I'm not advocating for old hardware. (facepalm)
More tips: use powertop. Use CLI-based stuff. Download email locally in bulk/batches.
Don't use software that does home-calling or any other unnecessary network traffic.
1 large monitor is more efficient than a dual screen setup
I'm not advocating for old hardware. (facepalm)
More tips: use powertop. Use CLI-based stuff. Download email locally in bulk/batches.
Don't use software that does home-calling or any other unnecessary network traffic.
1 large monitor is more efficient than a dual screen setup
AWS' James Hamilton lives pretty much on a boat around the world most of the time [0].
I was at AWS 2008-2014 and had a few chats with him. Super nice, very smart, humble. For a little while he used to be a car mechanic for Italian cars in his younger years.
[0]: https://mvdirona.com/
I was at AWS 2008-2014 and had a few chats with him. Super nice, very smart, humble. For a little while he used to be a car mechanic for Italian cars in his younger years.
[0]: https://mvdirona.com/
Probably a good thread to ask: A few years ago when looking for it, I was able to easily find deep-discharge 100Ah 12V lead-acid batteries at reasonable prices, which would have allowed one of my projects to go off-grid. However, what I couldn't find was a charge controller that would be able to reasonably e.g track charge and time. I didn't have the time and sufficient expertise to design such a charge controller myself.
My options ended up being buy a pre-made, significantly more expensive UPS and pay for the up-down conversion loses; Or just used my 12V feed with no monitoring and hope for the best. I chose the latter, which ended up OK given this was a research project with a limited time horizon.
Is the situation any better today?
My options ended up being buy a pre-made, significantly more expensive UPS and pay for the up-down conversion loses; Or just used my 12V feed with no monitoring and hope for the best. I chose the latter, which ended up OK given this was a research project with a limited time horizon.
Is the situation any better today?
There are many DIY charge controllers nowadays from aliexpress to commercial grade. I remember looking at them for LiFePO4 batteries but almost all of them will support Lead Acid since it's just a few more lines of code.
There are lots of solar charge controllers, cheap to expensive. If you want to track charge reliably, you'll need a shunt. Victron energy makes a good one which is monitorable via BT.
Depends on the wattage but I just bought a 20 watt charge controller for $30. If you're just trickle charging a lead-acid battery that's plenty.
Being that internet and power constrained would just stress me out frankly. One more thing to manage...
The author makes the claim that these constraints lead to more creativity and perhaps focus. I mean we both probably wouldn't be here if we knew we only had one hour of battery power for the day.
"off the grid" - except for the social media presence, the website, the cloud backups, etc which are all outsourced, on-grid, big power eaters. Articles like these always feel like Japan itself: clean, because all the trash and polluting industry was sent away to the rest of Asia.
/me grumps away
EDIT that said, there are good thoughts in the article, eg: "Hard copies: Paper is a stable and widely accessible material, unlike digital devices which are subject to breakages and obsolescence". I'll have to print a lot of photos one day.
/me grumps away
EDIT that said, there are good thoughts in the article, eg: "Hard copies: Paper is a stable and widely accessible material, unlike digital devices which are subject to breakages and obsolescence". I'll have to print a lot of photos one day.
Why live for years in the forest and write a book to be released afterwards when you can just show off how minimal you are in realtime? Thoreau would've just micro-blogged all of his thoughts on Twitter probably.
I wish the article had more details on their equipment and the pros/cons.
My office is off grid (not in my backyard), and a huge time sink was researching what components I need and which ones to buy. Now that I'm setup, I'm surprised at how cheap solar can be, considering most home setups are in the $15k+ range and don't get any storage.
My complete solar setup with battery was about $2000 (300W solar, charge controller, inverter, 100AH battery), and can be done today for $1200 (battery prices have dropped).
My office is off grid (not in my backyard), and a huge time sink was researching what components I need and which ones to buy. Now that I'm setup, I'm surprised at how cheap solar can be, considering most home setups are in the $15k+ range and don't get any storage.
My complete solar setup with battery was about $2000 (300W solar, charge controller, inverter, 100AH battery), and can be done today for $1200 (battery prices have dropped).
Why, when I got laid off due to funding, that I’m constantly reminded by my dream to set sail and work remotely. Dang it. This is my dream right here. Live off grid, conscious of my impact, and make a living doing what I love, being in the ocean.
I bookmarked this under “Retirement goals”.
Whether it’s an RV, a sailboat, a troller, doesn’t matter. Housing is ridiculous and I’d rather spend my time doing something adventurous than sitting around waiting for the grim reaper.
I bookmarked this under “Retirement goals”.
Whether it’s an RV, a sailboat, a troller, doesn’t matter. Housing is ridiculous and I’d rather spend my time doing something adventurous than sitting around waiting for the grim reaper.
That's pretty cool - reminds me about an experiment of improving small fridge efficiency by adding insulation on the sides of the fridge. In the end it worked out favourably for energy efficiency angle.
https://coolfridge.blogspot.com/
I'd be grateful if folks point out more improvements/builds that target off-grid home/office setups.
https://coolfridge.blogspot.com/
I'd be grateful if folks point out more improvements/builds that target off-grid home/office setups.
I was just thinking about that... first thing come to mind is that I need StarLink satellite internet (said to have at least 100Mbps 20ms latency). Electricity wise, I'm not running server farm out there. Solar, wind, geothermal, even gas generators should be fine.
Starlink draws about 100w without much variation unless you shut it off completely.
Maybe in the future they'll be able to offer a lower-power user terminal meant for mobile installations (RVs/boats/etc.)? There might be some opportunity there to reduce energy usage at the cost of some speed.
Great outlook on working culture and hours:
> We work less, by keeping our needs small. We both cannot deal with working within rigid schedules, and we both know that we find our best selves when working close to nature.
> We work less, by keeping our needs small. We both cannot deal with working within rigid schedules, and we both know that we find our best selves when working close to nature.
I’m off-grid in a jungle on the Big Island of Hawaii.
For internet I’ve been using a GlocalMe global portable modem with a data package and a VPN. Data is $100/50GB/month though I’ve realized I only use about 20/mo, and the modem talks to cell towers—all of them—and has its own data provisioning contracts. Internet solved—faster than tethering your phone.
For internet I’ve been using a GlocalMe global portable modem with a data package and a VPN. Data is $100/50GB/month though I’ve realized I only use about 20/mo, and the modem talks to cell towers—all of them—and has its own data provisioning contracts. Internet solved—faster than tethering your phone.
I have never found a nice, compact wing generator that i could use for a cabin in the woods or similar - that would be viable for personal use in a northern country
Solar seems to be doing so much better in terms of cost per watt, reliability (no moving parts), etc. Are there trully no decent wind turbines that don't break the bank?
Solar seems to be doing so much better in terms of cost per watt, reliability (no moving parts), etc. Are there trully no decent wind turbines that don't break the bank?
Off-grid, yes, but no electricity, not for me. Thanks for sharing an interesting article though.
I've lived for extended periods (up to 9 months) in my self-built Sprinter, with 550W of panels on the roof, and 455aH of battery inside. That system runs the lights, the fridge, the toaster, an electric kettle, the heater fan/pump, water pump, a 40W audio amp, and my purpose built computer.
The computer is a mini-ITX i7 quad core, with a "micro power supply" that lets me plug it (almost) directly into my batteries.
Things I've learned:
1) you can't plug directly into the batteries if you've got a smart solar charge controller. That will sometimes take the DC circuit voltage up to levels that the micro PSU considers unsafe, and the computer will shut down. I had to add a voltage regulator to keep the DC V levels seen by the computer (and other equipment) within range. My Morningstar charge controller will lift the DC V to 14V fairly often if there is a lot of sun and the batteries are moderately discharged.
2) Monitors are a problem. Some years ago, you could find monitors that accepted a standard 12VDC power plug fairly easily. Then someone figured out how to shrink the monitor PSU (thanks, Apple!) and they vanished inside the monitor case. You now have to hunt really hard to find anything that is 12VDC native. This is another argument in favor of laptops.
3) Native (desktop) software development is a totally different ballgame than webdev for this scenario. As I mention a lot here on HN, compiling my software is a major issue no matter whether I'm grid connected or not. It takes time, and it takes power. It actually takes more power than the refridgerator. If you're going to just "be online" all day, or just working in the cloud, or just pushing data to and from the cloud, you don't need much power (my setup would last for 4-5 days of that kind of work. But if you're going to be compiling code (i.e. 100% CPU utilization) for extended periods, you need a lot of power. That means panels and/or batteries.
4) Laptops offer more power flexibility in part because they have their own batteries. You can get them fully charged during peak insolation, which doesn't take long, and then allow the remaining sun to keep charging your main batteries. Sometimes you can get another charge into the laptop batteries before sundown, giving you another nice blob of energy to use in the dark. You can also use them outside the vehicle, which for some people is important (it isn't for me, in general)
5) I experimented in the beginning with a wifi antenna on an extensible mast. It connected to an internal router (also directly powered by 12VDC from the batteries/voltage regular). I gave all that up fairly quickly. Open wifi worth using is vanishing rare (thanks, telecoms). I ended up with a Verizon jetpack (grandfathered into an unlimited 4G data plan for US$70/month) and use that exclusively. It has been really great, generally even better than trying to use the wifi when we stay at friends/family.
6) in the not too distant future, I will switch out my aging AGM (lead-acid, but better) batteries for lithium ion, which will effectively double the size of our battery store (Li batteries can be fully discharged)
7) smart charge controllers are great for battery life but terrible for power collection. They will (correctly) limit the current to the batteries based on their current charge level, tapering off as the batteries near full. This can lead to situations where there is full sun available all day, but it still takes hours to get back to 100% because the charge controller is being careful and looking after your batteries. This is good for longevity of lead-acid batteries, but infuriating if you need to "bank" the power as fast as possible (e.g. its going to be cloudy this afternoon). This issue, IIUC, goes away with Li batteries, which are happy to accept about as much current as you can give them (they just need to be above freezing).
The computer is a mini-ITX i7 quad core, with a "micro power supply" that lets me plug it (almost) directly into my batteries.
Things I've learned:
1) you can't plug directly into the batteries if you've got a smart solar charge controller. That will sometimes take the DC circuit voltage up to levels that the micro PSU considers unsafe, and the computer will shut down. I had to add a voltage regulator to keep the DC V levels seen by the computer (and other equipment) within range. My Morningstar charge controller will lift the DC V to 14V fairly often if there is a lot of sun and the batteries are moderately discharged.
2) Monitors are a problem. Some years ago, you could find monitors that accepted a standard 12VDC power plug fairly easily. Then someone figured out how to shrink the monitor PSU (thanks, Apple!) and they vanished inside the monitor case. You now have to hunt really hard to find anything that is 12VDC native. This is another argument in favor of laptops.
3) Native (desktop) software development is a totally different ballgame than webdev for this scenario. As I mention a lot here on HN, compiling my software is a major issue no matter whether I'm grid connected or not. It takes time, and it takes power. It actually takes more power than the refridgerator. If you're going to just "be online" all day, or just working in the cloud, or just pushing data to and from the cloud, you don't need much power (my setup would last for 4-5 days of that kind of work. But if you're going to be compiling code (i.e. 100% CPU utilization) for extended periods, you need a lot of power. That means panels and/or batteries.
4) Laptops offer more power flexibility in part because they have their own batteries. You can get them fully charged during peak insolation, which doesn't take long, and then allow the remaining sun to keep charging your main batteries. Sometimes you can get another charge into the laptop batteries before sundown, giving you another nice blob of energy to use in the dark. You can also use them outside the vehicle, which for some people is important (it isn't for me, in general)
5) I experimented in the beginning with a wifi antenna on an extensible mast. It connected to an internal router (also directly powered by 12VDC from the batteries/voltage regular). I gave all that up fairly quickly. Open wifi worth using is vanishing rare (thanks, telecoms). I ended up with a Verizon jetpack (grandfathered into an unlimited 4G data plan for US$70/month) and use that exclusively. It has been really great, generally even better than trying to use the wifi when we stay at friends/family.
6) in the not too distant future, I will switch out my aging AGM (lead-acid, but better) batteries for lithium ion, which will effectively double the size of our battery store (Li batteries can be fully discharged)
7) smart charge controllers are great for battery life but terrible for power collection. They will (correctly) limit the current to the batteries based on their current charge level, tapering off as the batteries near full. This can lead to situations where there is full sun available all day, but it still takes hours to get back to 100% because the charge controller is being careful and looking after your batteries. This is good for longevity of lead-acid batteries, but infuriating if you need to "bank" the power as fast as possible (e.g. its going to be cloudy this afternoon). This issue, IIUC, goes away with Li batteries, which are happy to accept about as much current as you can give them (they just need to be above freezing).
Re (6): "which will effectively double the size of our battery store (Li batteries can be fully discharged)"
Not strictly true. You size your batteries for the rare times when you have long periods of no sun. By definition these rare occurrences shouldn't greatly impact the life of a lead acid battery. Especially flooded lead acid cells.
Conversely if you discharge your Li-ion cells 100% on a daily basis then you have no capacity for longer periods of no sun.
The "100% discharge" myth comes from grid-tied installations that are working their batteries hard each day to claim the surplus power rebate.
Re (7): "They will (correctly) limit the current to the batteries based on their current charge level, tapering off as the batteries near full".
The better regulators keep track of the state of charge (rather than just voltage), so are able to charge at the maximum safe current until the batteries are full. They don't "taper off" towards the end of charge.
It is true that most Li-iron batts can safely absorb greater current than lead-acid, but that is not the fault of the charge controller.
Not strictly true. You size your batteries for the rare times when you have long periods of no sun. By definition these rare occurrences shouldn't greatly impact the life of a lead acid battery. Especially flooded lead acid cells.
Conversely if you discharge your Li-ion cells 100% on a daily basis then you have no capacity for longer periods of no sun.
The "100% discharge" myth comes from grid-tied installations that are working their batteries hard each day to claim the surplus power rebate.
Re (7): "They will (correctly) limit the current to the batteries based on their current charge level, tapering off as the batteries near full".
The better regulators keep track of the state of charge (rather than just voltage), so are able to charge at the maximum safe current until the batteries are full. They don't "taper off" towards the end of charge.
It is true that most Li-iron batts can safely absorb greater current than lead-acid, but that is not the fault of the charge controller.
It is strictly true. 400aH of lithium allows me to use 400aH, over any period I choose, without deleterious effects on the battery. 400aH of lead-acid allows me to use 200aH if I want to avoid deleterious effects on the battery.
If I'm entering a period of no sun, 400aH will last me twice as long as 200aH.
The only way in which this is not true is if I'm prepared to use 100% of a lead acid battery's store, which negatively impacts the battery's life.
In a fixed home situation, it is true that you might have battery storage that so far exceeds your normal requirements that it is only necessary to go below 50% SOC twice a year. In such a scenario, I'd agree with you that you could do this and not worry about it. But it also means that you've got far more battery capacity than you need, just to cover the two days a year when you need to do this. Using Li would allow you to reduce the capacity, dip down below 50% SOC more often, without impacting battery life.
It seems that you're suggesting that my Morningstar charge controller might not be one of the "better regulators". I'd beg to differ. It is precisely "charge at the maximum safe current" that is what I mean by "tapering off". You cannot dump 18A @ 13V into lead-acids that are at 90% SOC without harming the batteries. The Morningstar (an MPPT controller) will modulate the current as the battery approaches 100% SOC, which as I said is precisely what you want for battery life, but precisely the opposite of what you want for "gather as much power as quickly as possible".
But yes, perhaps I did make it sound as if the charge controller was at fault for doing this, which is not true. I was describing it more as a kind of unexpected behavior that can oddly impact your battery use. For example, if you're somewhere that is very sunny in the mornings and then routinely clouds up in the afternoon, starting the day at say 85% SOC with lead-acids may not get you back to 100% even though there is sufficient power to do so - the charge controller will limit the current delivered to the batteries during the morning (correctly!), then the afternoon comes around and the power levels drop (this happened to me a lot in southern Spain for example). It's a somewhat surprising behavior if your mental model is "I've got 500W of panels on the roof, these babies should be recharged by 10:30am"
If I'm entering a period of no sun, 400aH will last me twice as long as 200aH.
The only way in which this is not true is if I'm prepared to use 100% of a lead acid battery's store, which negatively impacts the battery's life.
In a fixed home situation, it is true that you might have battery storage that so far exceeds your normal requirements that it is only necessary to go below 50% SOC twice a year. In such a scenario, I'd agree with you that you could do this and not worry about it. But it also means that you've got far more battery capacity than you need, just to cover the two days a year when you need to do this. Using Li would allow you to reduce the capacity, dip down below 50% SOC more often, without impacting battery life.
It seems that you're suggesting that my Morningstar charge controller might not be one of the "better regulators". I'd beg to differ. It is precisely "charge at the maximum safe current" that is what I mean by "tapering off". You cannot dump 18A @ 13V into lead-acids that are at 90% SOC without harming the batteries. The Morningstar (an MPPT controller) will modulate the current as the battery approaches 100% SOC, which as I said is precisely what you want for battery life, but precisely the opposite of what you want for "gather as much power as quickly as possible".
But yes, perhaps I did make it sound as if the charge controller was at fault for doing this, which is not true. I was describing it more as a kind of unexpected behavior that can oddly impact your battery use. For example, if you're somewhere that is very sunny in the mornings and then routinely clouds up in the afternoon, starting the day at say 85% SOC with lead-acids may not get you back to 100% even though there is sufficient power to do so - the charge controller will limit the current delivered to the batteries during the morning (correctly!), then the afternoon comes around and the power levels drop (this happened to me a lot in southern Spain for example). It's a somewhat surprising behavior if your mental model is "I've got 500W of panels on the roof, these babies should be recharged by 10:30am"
I’m planning to build a velomobile (and trailer) and live out of it for at least a year. One of the things I’ve been mulling over is computers, as I’d like to build or buy a new computer at some point in the not-too-distant future to replace my current dying laptop. How much power does your Mini-ITX machine use when idling? And have you tried to optimise it down?
I’ve been thinking of things like the AMD Ryzen 9 5950X, shutting down most of the cores when I want to conserve power in addition to severely underclocking it a lot of the time, but so that at times when power is more readily available or if I’m compiling lots of stuff, I can go all out.
I see figures for the last few generations of desktop processors of the whole machine using something like 50W when idling.
Meanwhile, I see a laptop with a 49Wh battery and an AMD Ryzen 5 4500U advertising ten hour battery life for a web browsing workload—which means that it’s averaging 5W for the computer and screen, when doing even a little bit more than idling.
So then I think, these desktop computers can’t actually be idling at that much power, right? That’s over a kilowatt hour per day if left on full time! Or at least, there must be some way of instructing them to use far less power, like a laptop would? (It’s a long time since I’ve dealt with a desktop computer to the level of knowing about power consumption.)
I’d love the power of a top-end desktop processor and to pair it with a carefully chosen and placed screen, but if that means an extra 50W or more of drain while it’s on, I might need to go with a laptop to make it through the winter.
(Many DC–ATX power supplies wouldn’t deliver enough power, but I believe https://www.mini-box.com/M4-ATX, rated at 250W (300W peak), should be just barely sufficient for a typical machine with any of AMD’s 105W CPUs, like the 5950X, and a 60–75W GPU like the AMD Radeon RX 560 (as powerful as you get before requiring an external power connector, which I haven’t spotted a DC power supply supporting, though I haven’t looked too hard), at full load. But slightly reducing the envelope of the CPU or GPU would probably be a good idea.)
Perhaps I should ask Metabox for details about https://metabox.com.au/store/Prime-Ai-Range (from the Clevo ODM) and what power it uses when idling. I’ve never seen a 230W AC adapter before!
I’ve been thinking of things like the AMD Ryzen 9 5950X, shutting down most of the cores when I want to conserve power in addition to severely underclocking it a lot of the time, but so that at times when power is more readily available or if I’m compiling lots of stuff, I can go all out.
I see figures for the last few generations of desktop processors of the whole machine using something like 50W when idling.
Meanwhile, I see a laptop with a 49Wh battery and an AMD Ryzen 5 4500U advertising ten hour battery life for a web browsing workload—which means that it’s averaging 5W for the computer and screen, when doing even a little bit more than idling.
So then I think, these desktop computers can’t actually be idling at that much power, right? That’s over a kilowatt hour per day if left on full time! Or at least, there must be some way of instructing them to use far less power, like a laptop would? (It’s a long time since I’ve dealt with a desktop computer to the level of knowing about power consumption.)
I’d love the power of a top-end desktop processor and to pair it with a carefully chosen and placed screen, but if that means an extra 50W or more of drain while it’s on, I might need to go with a laptop to make it through the winter.
(Many DC–ATX power supplies wouldn’t deliver enough power, but I believe https://www.mini-box.com/M4-ATX, rated at 250W (300W peak), should be just barely sufficient for a typical machine with any of AMD’s 105W CPUs, like the 5950X, and a 60–75W GPU like the AMD Radeon RX 560 (as powerful as you get before requiring an external power connector, which I haven’t spotted a DC power supply supporting, though I haven’t looked too hard), at full load. But slightly reducing the envelope of the CPU or GPU would probably be a good idea.)
Perhaps I should ask Metabox for details about https://metabox.com.au/store/Prime-Ai-Range (from the Clevo ODM) and what power it uses when idling. I’ve never seen a 230W AC adapter before!
I never tried to "optimize it down", because I essentially always had enough power (and on the very rare occasions that I did not, I just stopped working).
Laptop battery life is only accurate if you do typical consumer laptop-y things. If you develop native desktop software or edit video (maybe even audio) all day, those numbers are impressively optimistic.
I believe my mini-ITX system is rated 160W TPU. A full quad-core sustained compile would pull about 12A DC, or about 140W, but that included the monitor, voltage regulator and 40W audio amp. At idle, the same setup would pull about 2-4A, or 24-48W.
Laptop battery life is only accurate if you do typical consumer laptop-y things. If you develop native desktop software or edit video (maybe even audio) all day, those numbers are impressively optimistic.
I believe my mini-ITX system is rated 160W TPU. A full quad-core sustained compile would pull about 12A DC, or about 140W, but that included the monitor, voltage regulator and 40W audio amp. At idle, the same setup would pull about 2-4A, or 24-48W.
I have been doing home hosting and took interest in power consumption becasluse my server is, well, idle most of the time.
My mini-ITX server pulls 14 watts most of the time, has i3-8100 and no GPU. This idle power seems to vary greatly by motherboard. Additionally, you will have to pair a ryzen with a GPU, and my older GPU consuned over 50W even when idle, i uogrades to send-hand vega and power consunption dripped significantly.
My mini-ITX server pulls 14 watts most of the time, has i3-8100 and no GPU. This idle power seems to vary greatly by motherboard. Additionally, you will have to pair a ryzen with a GPU, and my older GPU consuned over 50W even when idle, i uogrades to send-hand vega and power consunption dripped significantly.
Just for reference, my van system has one of these inside: https://www.mini-box.com/picoPSU-160-XT
Thank you so much for posting this! Found it a while ago and found it very inspiring, but I recently tried to find it again without succeeding. So thank you!
It would be interesting how much power you could generate by having a little outboard propeller driving a small generator. It would decrease the speed of your yacht, but if you're not on a schedule to get anywhere who cares, right?
Another option would be using Peltier effect, although I have no idea how efficient it could be. But sailing in the Polynesia, I'd think that there's a good temp difference between the water below the surface and the top of the boat.
Hydro generators exist! They are relatively expensive for the small amount of power they generate: https://www.sailmagazine.com/diy/know-how-hydro-generators
They're not fool proof yet and can take a bit of tending unless you really spring for the top of the line. Particularly important is the blade pitch, on the more affordable models that has to be set manually and if you go too fast with an aggressive pitch intended for a lower speed you can break the unit very quickly.
What is a typical price?
According to the article I linked, one that gives max 600 watts costs around US$5000.
The market is very small for hydro generators for sailboats.
Solar is much cheaper because you can buy products that are targeted at mass market instead of only at sailboats.
Source: I was recently purchased by a sailboat.
The market is very small for hydro generators for sailboats.
Solar is much cheaper because you can buy products that are targeted at mass market instead of only at sailboats.
Source: I was recently purchased by a sailboat.
I was recently purchased by a sailboat.
And what does your sailboat intend to do with its new purchase?
And what does your sailboat intend to do with its new purchase?
Suck his wallet dry is the usual goal I believe.
Sailboats are very much like a reverse merger.
The two happiest days of a boat owner's life: the day they buy the boat, and the day they sell the boat.
The two happiest days of a boat owner's life: the day they buy the boat, and the day they sell the boat.
Take it for all it's worth!
SV Delos has a great video on power generation methods https://www.youtube.com/watch?v=Osh1ljtgnSU . It is a larger boat (58ft?) that is lived on full time and they use a combination of solar, wind and fossil fuel for energy.
In another video (can't find it offhand) they talk about propeller driven generation and how it isn't a great solution for them. Propeller driven generation is expensive, it requires another hole in the bottom of the boat, requires maintenance (marine growth), it only works when the boat is moving, and its power ultimately comes from the wind or fossil fuels. Why not get the energy from the wind directly using a wind generator? It's cheap, effectively maintenance free, runs whenever the wind blows even at anchor, and if you're running the engines, more efficient to generate electricity using the generator. They have the wind generators mounted above and slightly off the back of the boat, where they are out of the way and remain permanently.
They mention their energy generation mix is about 10% wind, 25% fossil, and the rest solar, using 3 panels. Their numbers were generated in low latitudes where solar insolation is quite high, so kind of the sweet spot for solar. I imagine further north wind generation is comparatively more useful. I know more recently they have added some flexible panels on the canopy which added a bit more capacity.
I'm guessing that Peltier generation is not going to be effective for anything more than fractions of a watt. The studies I see online all work with larger temperature differentials, like > 50 deg C, which you aren't going to find anything close to in a thermocline layer. To work with a smaller temperature differential you would need to increase surface area immensely, and water is a high-drag environment.
I found it interesting that one of the more power-hungry things on a sailboat is fresh water. Watermakers consume 15-30 Wh of energy per gallon, and a boat will need about 20 gallons per day per person. For a 4 person boat, that 80 gallons requires 80*15=1200Wh each day. Most sailboats will use the generator to fill up the freshwater tank because they don't have enough solar capacity.
In another video (can't find it offhand) they talk about propeller driven generation and how it isn't a great solution for them. Propeller driven generation is expensive, it requires another hole in the bottom of the boat, requires maintenance (marine growth), it only works when the boat is moving, and its power ultimately comes from the wind or fossil fuels. Why not get the energy from the wind directly using a wind generator? It's cheap, effectively maintenance free, runs whenever the wind blows even at anchor, and if you're running the engines, more efficient to generate electricity using the generator. They have the wind generators mounted above and slightly off the back of the boat, where they are out of the way and remain permanently.
They mention their energy generation mix is about 10% wind, 25% fossil, and the rest solar, using 3 panels. Their numbers were generated in low latitudes where solar insolation is quite high, so kind of the sweet spot for solar. I imagine further north wind generation is comparatively more useful. I know more recently they have added some flexible panels on the canopy which added a bit more capacity.
I'm guessing that Peltier generation is not going to be effective for anything more than fractions of a watt. The studies I see online all work with larger temperature differentials, like > 50 deg C, which you aren't going to find anything close to in a thermocline layer. To work with a smaller temperature differential you would need to increase surface area immensely, and water is a high-drag environment.
I found it interesting that one of the more power-hungry things on a sailboat is fresh water. Watermakers consume 15-30 Wh of energy per gallon, and a boat will need about 20 gallons per day per person. For a 4 person boat, that 80 gallons requires 80*15=1200Wh each day. Most sailboats will use the generator to fill up the freshwater tank because they don't have enough solar capacity.
Small wind generators at the top of the mast and a few other places might help.
We're living on a boat. We have 600W solar and that's sufficient for most of our power needs. Of course living off solar means on some days you'll not be doing GPU intensive stuff on the computer (which tends to turn it from a low-power, quiet machine into a hyperventilating 90W monster), but that's fine. We usually have enough power left to run the 12V watermaker.
Biggest problem is crap software. Everything seems to be designed to be online all the time and expect you to have unmetered high-speed internet. We often have various combinations of metered, slow and unreliable (packet loss, high latency spread, interruptions). Nobody even tests their software for this scenario anymore.
Obviously you can forget about using Xcode with its multi-GB updates every couple weeks. Or any cloud software. Even MacOS gets annoying, as it wants to verify an app before starting it and if the connection is flakey it can take a minute before that request either goes through or is detected as offline and your app finally starts (yes, I know you can turn that off).
Websites with dynamic forms often don't work, as the programmers falsely assumed their XHR always goes through and never implemented retries or network error handling. Download pages that generate dynamic URLs are a big sin too, so when you try to continue from a partially downloaded file you can't because your URL is no longer valid.
What works well is keeping data offline but occasionally syncing it, like IMAP for email, Unison file sync, etc.
Piracy is also important, because when you travel from country to country, geo-IP blocking is a constant problem. Suddenly the TV show you were in the middle of watching is no longer available in your country (because you sailed to another country) or the entire service is blocked (Amazon Prime Video). And it's safer to use cracked software that won't suddenly stop working because it couldn't contact its license server in a while or demands you to download a multi-GB update. Or software that doesn't require such nonsense.
Hardware is less of an issue, if you keep it dry, which requires some care, but so does the rest of boat life. I've had a keyboard die from circuit board traces corroding away, but am still on the same 8 year old laptop. Had one netbook get accidentally wet once, but managed to save it by immediate taking apart and rinsing out with alcohol. External drives are kept in waterproof plastic food containers.
Backup is offline only and consists of two external drives in another waterproof box, which go with the grab bag (the one you take with you if ever have to abandon ship). There is no real need for off-site backup, as the nature of life on a boat means either you and your grab bag make it off the boat, or neither (in which case you won't be needing your data anymore).
Biggest problem is crap software. Everything seems to be designed to be online all the time and expect you to have unmetered high-speed internet. We often have various combinations of metered, slow and unreliable (packet loss, high latency spread, interruptions). Nobody even tests their software for this scenario anymore.
Obviously you can forget about using Xcode with its multi-GB updates every couple weeks. Or any cloud software. Even MacOS gets annoying, as it wants to verify an app before starting it and if the connection is flakey it can take a minute before that request either goes through or is detected as offline and your app finally starts (yes, I know you can turn that off).
Websites with dynamic forms often don't work, as the programmers falsely assumed their XHR always goes through and never implemented retries or network error handling. Download pages that generate dynamic URLs are a big sin too, so when you try to continue from a partially downloaded file you can't because your URL is no longer valid.
What works well is keeping data offline but occasionally syncing it, like IMAP for email, Unison file sync, etc.
Piracy is also important, because when you travel from country to country, geo-IP blocking is a constant problem. Suddenly the TV show you were in the middle of watching is no longer available in your country (because you sailed to another country) or the entire service is blocked (Amazon Prime Video). And it's safer to use cracked software that won't suddenly stop working because it couldn't contact its license server in a while or demands you to download a multi-GB update. Or software that doesn't require such nonsense.
Hardware is less of an issue, if you keep it dry, which requires some care, but so does the rest of boat life. I've had a keyboard die from circuit board traces corroding away, but am still on the same 8 year old laptop. Had one netbook get accidentally wet once, but managed to save it by immediate taking apart and rinsing out with alcohol. External drives are kept in waterproof plastic food containers.
Backup is offline only and consists of two external drives in another waterproof box, which go with the grab bag (the one you take with you if ever have to abandon ship). There is no real need for off-site backup, as the nature of life on a boat means either you and your grab bag make it off the boat, or neither (in which case you won't be needing your data anymore).
Meaning much bigger constraints in weight. 10 years ago, it was really expensive getting the equipment, I used a solar gorilla/power gorilla pack. Very nice, but also heavy. I think around 500€.
Today I use 2 Anker 21 solar W and 3 power banks for half the price and at least triple the power. (downside is only USB charge, meaning not possible for many laptops, unlike the power gorilla)
Also laptops really improved in battery life and power efficency, meaning, when I started doing it 10 years ago, I could only really work consistently, when I had a real power source nearby. Otherwise it was maybe 2 days of full-time working.
Today I can work forever off the grid, on my cheap rugged Asus Chromebook, as long as the sun shines from time to time and I have a safe place to put up the solar panels. All in all my mobile office equipment is 4-5 kg. For short trips with laptop, 1 panel and 1 powerbanks, cables,.. 2.5 kg. Which is managable, even when you carry also your tent and food.
Combining working in nature really helps my creativity and I can recommend trying this out. The tech really is ready today, unless you want to do heavy video editing or 3D Design.
But coding, in my case mainly with chrome dev tools and node, really works fine off grid. There are new insights to be gained, from top of a mountain, tree, or next to a river, compared to your never changing office wall.