I'm in CA so solar makes all kinds of sense (we pay like $0.27 per kw/h). For us it was a 4 year payback that we did over 4 years ago, so it's all gravy now. But if you have a low kw/h rate your money could be better spent doing something else: maybe dropping it into the market (which as I understand has dropped so maybe a good time to buy). Or hold on to that money and buy some real estate at low value...

But I agree, you should not hold it in cash with inflation as it is.