@Nigel_Purchase

I paid USD$30,000 to install a 10KW solar system on my roof, and this has been the wettest, cloudiest, rainiest winter Southern California has had in decades. I went back and reviewed, and from Feb 1 to today, there have only been 6 days my solar panels didn't produce all the power my house uses - most days it was more, and on cloudless days, it was 2x+.
Because of US policy, I was refunded $9,000, so my actual out of pocket was USD$21,000. Not bad.