SDN is great if you're trying to build something like a multi-tenant cloud on top of another network of machines. Your DPUs can handle all the overlay logic as if there was a top of rack switch in each chassis
To give a concrete datapoint, last month's bill was $820 for just the electricity generation and transmission (so no gas included) - that was for 1900 kWh for 1 month. That handles a 2000 sqft house with central AC, with two EV cars that are driven about 20mins/day, and we only charge those at night when the rates are low (low=$0.3/kWh)