Winter vs summer sun angle

[jimindenver]

When designing a system for the worse of times, short winter sun hours are discussed. Lower sun angle reduces the amount of power you get in that shortened day too. I have a 230w panel on my truck keeping the bank happy over the winter and at 10 am it is producing a little more than half what I would expect at the same time in the summer.

The effect is less for Bob in Az. and more for someone in the U.P. of Michigan. Many full timers have their panels tilt to make up the difference. My flat system is designed to be marginal in the winter, a power plant in the summer and if it can't keep us going, a tracking portable will be used before the generator.

Just something to consider beyond the nuts and bolts of a system.

 

[regis101]

Yep. The angle of the dangle never ceases to amaze me.

Just yesterday, while setting at the traffic light, I noticed the corner light pole shadow was longer than the pole itself. Even the traffic motion sensors are blinded enough to disallow its proper function thus making me sit there until it times out.

Not to drift off topic but just stating an observation.

 

[GaryGary]

Hi,
PVWatts is a really nice and easy to use tool to put numbers to how much less you will generate in the winter than in the summer.

You just pick your location and tell it the way the PV array is pointed, and it will give you month by month totals for your PV panel for your location and your average weather and your panel azimuth and elevation.  You can run it several times with different tilts and see how much difference it makes.

PWWatts is done by NREL -- its free and they have no sales agenda -- just google PVWatts.

My own conclusion given that I don'e use the RV much in the deep winter, that it was not worth doing the tilt up panels -- but may be different for you.

Gary

 

[regis101]

http://pvwatts.nrel.gov