Panel Tilt & Spacing

[Danke]

OK, I have had a few installers look at my flat roof. I’m at 45N 93W in Twin Cities, MN.

One said they found 12 degrees to be the best overall, another one said 35 degrees.

Steeper is obviously better for snow consideration and power generation in winter. The biggest downside seems to be the increased spacing require to minimize shadowing aft rows of panels and therefore fewer panels overall. Also, I have Net Metering, so I could possibly sell back more in summer if panels have lower tilt angle.

I have gone to a few website calculators, seems to add to my confusion. LOL. https://www.cedgreentech.com/article/determining-module-inter-row-spacing

I’m thinking with my most aft row, I’ll jack the tilt to over 50 degrees, and set the other rows to ~25 degrees as a compromise.

Any thoughts?

 

[Steve_S]

Location: Nearest City is ?

I am up North, Algonquin Park Ontario Canada area. Closest City is Pembroke Ontario.
My system is Ground Mounted for optimal year-round performance which is actually 4 Degrees Angle, facing Direct South. Max Production occurs in March & September. Even @ 45deg, I occasionally have to go and clear off the panels using a FOAM Scraper, so I left a 4' space from the bottom of the panels to grade, even that has to be cleared at least a couple of times a winter.

Try this Solar Angle Calculator, simple easy and pretty good.

Solar Angle Calculator

The solar angle calculator tells you by location the optimum angle to get the best out of your system.

www.solarelectricityhandbook.com

Then use this Solar Irradiance Table to see how many SunHours you will get in your region which s very helpful to figure out Charge Time potentials especially if you are in North Country dealing with snow.

Solar Irradiance Calculator

www.solarelectricityhandbook.com

I ought to point out a peculiarity that many don't get... Snow is a Wonderful Reflector and I've had my system kick into HyperVOC a few times on really bright sunny cold days (never expected that given angles but it happens). HyperVOC is something that belongs to Midnite Solar Classic & Other controllers, this allows for extra volts/amps above spec coming from the installed panels. This si NOT a feature that many companies have in their systems.

 

[Maitake]

Download free System Advisor Module software, it will tell you very closely what output you will get it includes albedo, tilt and row spacing.
Warning: it does not yet include current limits in your MPPT. Took me a while to figure that out.

Snow is great with bifacials, jan feb march will be my biggest production months by far. Right when I need it.

 

[Danke]

Good to hear. The installer/quotes I got said bifacial weren’t worth it in my situation. But my research said it could help some. So I bought 460W Bifacials. I have a white, flat roof and get snow.

 

[Steve_S]

 

[Danke]

Ya, I got that. Will try that software also to see about spacing/shadowing. I read that even though a lower angle is not optimal, with limited roof area it makes sense because more panels outweighs the angle/tilt gain.