Solar panels were made in China. The reason that solar panels are so cheap there is that the state has bankrolled these companies to produce them at a massive scale.

This only makes sense way downstream of massive subsidies, not the least of which is China determining at a federal level that they wanted to produce an obscene amount of solar panels.

And now it's complicated because the ideal move would just be to say "thank you" and buy all the cheap panels and batteries, but that hollows out your own industry.

There were significant state subsidies and regulation changes to encourage home battery installation. That's a lot less "free trade" driven than the GP post indicates. Is that still capitalism being an excellent system?

a $3,000 battery subsidy is the opposite of free trade.