ktmrfs wrote:Today, at solar noon in Portland (when you would get peak charging current), the solar altitude was about 62 degrees. That's 28 degrees off normal (perpendicular, AKA zenith angle) for a horizontal panel. cos(28)~=.88, so the panel would receive about 88% as much light as it would if positioned normal to the sun. It's a bit less than that due to thicker atmosphere at lower angles, but not much unless the sun is much closer to the horizon. To get only 1/3 the output is due to factors other than the sun angle. The sun would have to be closer to 20 degrees altitude (that's like 8-9AM) to produce that output based on sun angle (or clouds, haze, shadows, etc.).
I've got in theory 60A total charging current. Now that's in theory, and today with the roof panels flat and being near 45 degrees latitude the sun angle limits the roof panels to around 20A total.
