7.3% return, not bad. As battery prices drop it will get even better.

It's not 7.3% return rate. There's some depreciation you need to add there.

	▲	WheatMillington 3 days ago \| parent [-]
		If you're going to depreciate the battery then your return will be substantially greater than 7.3%. You can't use BOTH the capex AND the depreciation as your denominator, choose one.