I bought one of the solar chargers they sell at Harbor Freight for around $20. They are made to charge a 12 volt battery at 1.5 watts. Granted that is not a lot of power, but just to keep a battery topped off, it worked fine.
I particularly bought it to keep a car battery charged for a battery powered electric fencer, but I also took it when I went camping, so keep my car battery charged after running my laptop computer off the car's battery without starting the car to recharge the battery. The computer often ran for several hours to play movies.
Anyhow, aside from the fact that it's cheap Harbor Freight junk. It stopped charging completely. There was a blue LED on it that would indicate it was charging, and that LED no longer lights in bright sun, and my volt meter shows no output.
I took it back to HF, but was told that unless I had bought their COSTLY extended warranty, it was only warranted for 3 months. Of course they tried to sell me another one, which was on sale at the time for $15, and their $10 for 2 years extended warranty. I told them I would not buy another one and would never buy anything from them again. (And I wont).
Anyhow, my question is what can go wrong with a solar panel? It was not dropped, smashed, cracked, or anything that would physically damage it. Since it's junk anyhow, I am going to try to open it, but it appears the screws or (whatever) holds the two halves of the case together are embedded in some sort of plastic. So, I guess drilling them out is my only way.