Solar is great but the bottleneck is on battery capacity to carry those noon hours into evening for peak usage. Last I checked we had plenty of lithium and are mostly held back on refinement.
Persisting a log of events. Used with CQRS and event-sourcing to decouple the Read model(s) from the Command layer for benefits like: multiple read models (projections), time-travel and audit-ability (rebuild the read model to certain point in time), and decoupled contexts.
Event-sourcing can be a really useful tool in many domains, but especially where having a state-of-the-art audit log is helpful.