A solar panel on the patio charges car batteries under the house. Those car batteries charge up some smaller AA batteries that go in motion activated LED lights in the halls etc. The inverter wastes some power so it would be nice to have a NimH charger that runs off 12V DC rather than 110V AC. Eneloop batteries are the coolest because they have a very low self-discharge rate. That doesn’t really matter for this application because they’re drained pretty frequently, but it’s cool nonetheless.