Yes, car/truck batteries can be charged via solar panels, though they have far less capacity than storage batteries.
As for farming, if you got a stable base, it’s best to plant them sometime around spring when it’s warm enough. You can add fertilizer to speed up their growth, and you can do that multiple times as the plant is growing. Like when you’ve planted it, put some fertilizer in, and you’ll be able to put fertilizer in again once they become seedlings, then again when they become mature plants.
Not sure if this is a quirk, but if you don’t harvest plants when they’re ready to be harvested, the amount of plants you can harvest will keep growing, at least for the plants that won’t rot like wheat/dandelions/etc.
For example, when I’d plant hops then immediately harvest them when they’re ready, I’ll get around 10 hops flowers per plant. By accident, I forgot to fertilize one hops and blueberry tile, and while the rest were ready to be harvested, it was a day before winter and it was doubtful that those two would be ready for harvest. This was on a previous base of mine and I left those two to presumably wither away during winter.
But they didn’t. By chance I went back to that area on spring and found that those two were ready for harvest. When I did, I found that the hops and its seeds were several times more than what I usually got when I harvested them immediately. The blueberry had normal amounts, probably because some of them rotted away being perishable and all, but like the hops there were much more seeds harvested.
It makes farming more convenient for me as I don’t have to plant so many seeds multiple times. Just waiting for the start of winter to harvest several 3x50 farm plots.
