Originally Posted by s/v Jedi
It's your option B: a cell that is shaded puts itself in a state of high impedance, blocking the current. The bypass diode then takes the whole string out. I don't know how many cells and strings this panel has, but orient it so that a re-occuring shade aboard like from the boom or mast
, does not go across all strings which would kill them all. The strings should be oriented in parallel with the shades, minimizing the problem.
This is exactly what many don't do or don't understand. Planning for this can improve daily output by 25%.
This is 100% correct.
As for shadow orientation, the advantage to optimal panel orientation can be much better than 25%. My three panels
are on top of the dodger
, under the boom. This is one of the worst locations I could have chosen, but I did so with my eyes open. The three are oriented port, mid, and starboard. On average one of the three is badly shaded. I generally get 2/3 of the potential panel output.
Had I installed the panels
fore-to-aft, the boom shadow would typically be running across all three panels, reducing the output horribly. In most conditions I would still get perhaps 10 or 20% of the potential output because the shadows are rarely "black" -- cloud cover and water
vapor diffuse the light enough to wash out the shadows a bit.