What panels did you use and how did you connect them?
6" x 6" solar cells bought on eBay. Get A grade, the others are inconsistent and lower power. If you buy a kit instructions come with it, I believe, but they are available on the net if you google. The cells can bend a little, enough to follow the normal bend of a deck. And use diodes, there are special solar cell diodes that are only a millimeter high and have minimal voltage drop. You also need a charging device, I got one good for 30 A that is automatic, can use from 36 to 72 cells and charge 12 V or 24 V.