Ron Jones wrote: > <scientist hat on> > Could probably more than that... > The suns rays are more or less parallel, therefore as the panel is tilted so > less sun hits the panel. If we have the panel at 90deg to the sun then we > get max power, if it's at 0deg (i.e. edge on) then we get zero power - so > just look up sine tables and x 100 to get a %age > http://www.mathnstuff.com/math/spoken/here/2class/330/sincost.htm > Sine 90 is 1 (100%) Sine 0 is 0 (zero) > Panels at, say, 60deg / 45deg / 30deg give results of 86.6% / 71.9% / 50%. > This is theory - note that the panel has a transparent covering - at the > lower angles, it's going to start to act like a mirror and reflect the sun > away, so the lower figures above will be even more worse, than compared to > the high ones - one may find that at 10deg it's all reflection and no > absorption. So flat on top of the boat in the winter is naff all use.
Unfortunately, the real world is not that simplistic. Under sunny conditions those figures are doubtless a reasonable approximation. However, under cloudy conditions there will still be an energy output from a panel. The optimum angle under cloudy conditions with diffuse illumination is probably pointing straight up. The panel output will be quite a lot less than under sunny conditions, but not necessarily trivial. In typical winter weather, it may be (and I have no data to back this up, it's a guess) that as much or more energy is produced from scattered, diffuse radiation as from direct insolation. So, flat on top of the boat may not be a bad thing in winter. Has anyone any actual data to confirm or refute this? Wassail! -- Martin Phillips [email protected]
