I'm with everyone else, Solar then Car, and here's the logic.
Mathematically, paying down the highest interest rate (solar) is the most cost effective. Psychologically, studies show, paying down the balances that you can pay off more quickly in most people's cases actually lead to quicker debt elimination. The solar in this case fits both, highest interest rate and should be quickest to pay off.
As far as the Car vs the Home, even though the interest rate is higher on the car, the amount is likely actually less due to the tax advantages of deducting the Mortgage Interest. That, in conjunction with paying off 50k can be done significantly quicker than 600k, which is the better in terms of the psychological effect.
My final thought is, since you're on bigger pockets, I'm assuming you're interested in real estate investing. With that said, with the exception of high interest debt, it's typically better in the long wrong to use available cash to invest. I've done about a gagillion spreadsheets calculating debt paydown vs putting it toward my real estate investments and in all cases of mine, using the cash towards real estate was always better in the long run. David Ramsey may not like that statement, and of course any investment has risk. However, as long as they're calculated risks, I'd consider that option as well.