Flux, when you sat "series string", are you talking about each string of 7 cells, or the entire 49 cells in series?...either way, my layout is 7 X 7 cells in series for 24.5 OCV & @ 4W per cell, 196 theoretical watts. That is one panel. For this post, I'll just talk about the poly panel...panel has 7 strings of 7 cells...diodes between 1&2, 2&3, 3&4, 4&5, 5&6. I don't have diodes on 1 or 7 because they are accessable externally. (the red & black wires). Would I be better off, say, if I just left 1 in towards the middle of the panel...I could also add externally to the leads if I have to. How much wattage do you think the extra diodes are costing me? When I was building it, I DID see a slight Vdrop across the diodes, but I didn't think it would add up to much once the sun hit it....now I'm thinking I may have shot myself in the foot (LOL)