Quite different is the investment of RAVPower. The charger is well packed and looks like a small laptop. It is very light and easy to handle and folded and placed in a few seconds apart. In a side pocket in the one cell phone possibly can also accommodate - there are 2 USB ports, on the one charged devices easily infects.
It is important that you have a good and clear view to the sun and no windowpane therebetween (glass absorbs already quite a lot of energy).
In the package are also carabiner and eyelets on charging devices, so you can fix it eventually.
We are very happy with it. On nice sunny days you can even recharge your device for 3 to 4 hours. Quick and easy. It works great and is easy.
And it has thus always current road if no outlet near as hiking or camping.
Conclusion: Super the solar charger from RAVPower and cheap when you consider how much cost as a solar cell even a few years ago. Takes up little space and is easy. Is it possible to have all this and there on sunny days a lot of power to mobile phones and with free green electricity charge. Good investment for the future .....