In reply to https://social.johanbove.info/2022/08/05/predicting-that-alternative-ways-of-generating-electricity. Reading a pro (!) …

Reading a pro (!) cyclist can crank out about 400 W for some 20 minutes, and maybe 250 for a few hours—comparable to, or perhaps a bit better than, a single solar panel.

That said, exercise is a great way to keep warm!