I do or have done what the other posters mentioned: Make sun tea, dry and sanitize clothes in the sun, heat water, open curtains to help warm the house. The first experience I had with solar power was when I decided to experiment, having read just a little about it. I had an old glass percolator and I painted a one pound metal coffee can (remember those?)with black chalkboard paint, since that's what I had on hand. I filled the coffee can with cold water, put on the lid and set it in the percolator in the sun. If I remember right, there was snow on the ground. When I went back a few hours later, the water was hot enough to wash dishes, although there wasn't enough for that. That convinced me.
Besides those things, I've left dingy whites on the clothesline for a few days to let the sun bleach them and of course, the sun grows part of my food. I dehydrate food in my car parked in the sun for heat. In the winter, if I have to go anywhere in the morning, I park the car at night so that it gets the sun early. That way, the engine and the interior are warm and I can just get in and go.