Not applying flux when connecting the solar cells together

When you are connecting the solar cells together, the most important thing you need to do is make sure to apply flux before soldering them together. Not only do you need to apply flux, but make sure you apply enough of it. Flux is what allows the solder to stick to your solar cells. If there's no flux or not enough of it, the tin wires that you solder onto the solar cells will not make good contact and in most cases, will not stick properly. The easiest way to make sure you don't encounter this problem is to use a flux pen. This will allow you to easily apply an adequate amount of flux every time you use it.