Doing a bad soldering job on the front of your panel will not only look ugly, it could potentially cause problems when you decide to cover your newly-assembled panel. Doing this on the back though, could be the end of your cells. The extra solder will push up your cells from the flat back cover and could damage them. Location, location, location decides the fate of businesses and solar panel projects alike. That may be a bit of an exaggeration, but power. Just because you managed to build a solar panel, or you bought one already assembled, and installed it does not mean your green energy adventure is over. Panels must be cleaned.