Want to install solar, questions

BFL13 wrote:
Down South in summer, sun is so high flat panels can be close to max.

"roof panels have one downside for most uses. the optimum tilt angle for getting rated power needs to be about the latitude your at plus solar declination. That means something around 45-60 degrees tilt. depending on location and time of year. "

Actually that's for winter up here. In summer,

Lat MINUS Dec = Tilt in northern hemisphere with north Dec

Since tilt (up from flat) = Zenith distance (90- sun's altitude above horizon) and ZD plus Dec = Lat at high noon, sun bearing S.

EG, 21 June Dec 23N at 49N---- Alt 64, so ZD is 26. 26 + 23 = 49

Same day down at 32N, tilt is 32-23 = 9 (almost flat)

Optimum tilt for a panel fixed pointing south is less than the noon angle so it can get more light in the shoulder hours. See macslab.

If you have a tilted panel on a twirler always pointing at the sun, however, you want it tilted higher in the shoulder hours than at noon which is your lowest tilt.

yup, your correct on summer vs. winter, my mistake thanks for the correction.

Since we are almost always near or above 45 Lat, angle does make a noticeable difference in the early spring and late fall. And that's when we use the furnace more and less sunlight hours. All adds up. But your correct, not near the effect in mid summer months.

Still, 45 degrees tilt error is a 30 percent hit, however if you can get below a 30 degree tilt error then you get around a 15 percent loss, not bad, anything less than a 15 percent tilt error is basically lost in the noise as you mention.