Used this during the weeklong Texas power outage of Feb 2021. I learned that:
1. In the winter, the sun would be so weak that this small solar panel would charge very slowly, or not at all on cloudy days. The only way this solar panel would charge at a rate that you'd expect is if there is FULL SUN and you have positioned it DIRECTLY for HOURS in FULL BLAZING SUN. Makes sense, right? Ideally, you should have some way of positioning it flat on a rooftop, but if you are in an apartment building with no way to go outside, it has limited use against a window, no matter how bright it may be outside.
2. I bought this small one for portability, and also as a relatively inexpensive "starter" set with a Jackery 160 power station. The small surface area of the solar panel means less catchment of sun's rays. I suppose I could use it while camping, but it is fragile to transport.
3. In the end, I can see myself using the power station only, and not the solar panel. You might consider saving yourself some money. Unless you are doing outdoor camping, in high summer. In which case, buy the biggest solar panel you can afford for full catchment of the sun's rays, not this little one.