Mount Angles

Fatawan
Fatawan Solar Expert Posts: 71 ✭✭✭
in General Solar Power Topics #1
My utility has a net metering setup whereby you are credited kWh's for excess energy you produce which go to offset kWh's consumed when you don't produce excess. The program is annual and squares up every April. There is no carryover to the next year. Am I right to assume, then, that it doesn't really matter WHEN I produce my energy as I am not trying to offset a specific use, it only matters HOW MUCH I produce over a given annual period? Thus, if mounting at 25 degrees produces a similar number of kWh's as a mount at my latitude of 41 degrees, then why not do it? The advantage of 25 degrees is a smaller vertical footprint for my array, and shorter poles for mounting.

Thanks as always.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Mount Angles

    you are correct that you are going for the max yearly production. that sweet spot is a lower angle than your latitude.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #3
    Re: Mount Angles

    Not sure what you mean by smaller vertical foot print, perhaps less visable?

    I believe your correct on the netmetering without carry over. something to consider is if the panels will be as 'self cleaning' at 25 degrees? If it means you need to get on to your roof 4x a year to clean them...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    #4
    Re: Mount Angles
    Fatawan wrote: »
    My utility has a net metering setup whereby you are credited kWh's for excess energy you produce which go to offset kWh's consumed when you don't produce excess. The program is annual and squares up every April. There is no carryover to the next year. Am I right to assume, then, that it doesn't really matter WHEN I produce my energy as I am not trying to offset a specific use, it only matters HOW MUCH I produce over a given annual period? Thus, if mounting at 25 degrees produces a similar number of kWh's as a mount at my latitude of 41 degrees, then why not do it? The advantage of 25 degrees is a smaller vertical footprint for my array, and shorter poles for mounting.

    Thanks as always.

    Don't forget to take weather patterns into account.

    For example, even though the days are longer in the summertime, where I live July and August are in the middle of the Monsoon season so it's often cloudy.
    My trackers have an adjustable elevation angle and I adjust them 2 to 4 times a year to maximize output.
    I STILL produced more energy in January than I did in either July or August.

    The online PVwatts program takes average weather into account. You might try playing with elevation angles and see which one produces the maximum annual output in your area.

    http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/
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  • Fatawan
    Fatawan Solar Expert Posts: 71 ✭✭✭
    #5
    Re: Mount Angles

    Photowhit--I just meant how tall the racking would be--shorter is better.

    Peter--July and August are driest here. It's best to shoot for summer output. My latitude is 41 degrees, optimum year-round production is 33 degrees, and I lose only a hundred kWh or so with 25 degrees(according to PVWatts).
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  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    #6
    Re: Mount Angles

    To complicate it even more, if you have or could have a time-of use rate plan with your utility, you could really go after that afternoon, summertime, on-peak power by lowering the tilt and even aiming the array somewhat westward. You want to produce as much of your power during the high-dollar on-peak times then at night during the off-peak hours you use utility power at a much lower rate. Most of these plans have higher rates in the summer than they do in the winter. Call your utility - they are usually very cooperative in helping you to decrease their peak loads.
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  • Fatawan
    Fatawan Solar Expert Posts: 71 ✭✭✭
    #7
    Re: Mount Angles
    solarix wrote: »
    To complicate it even more, if you have or could have a time-of use rate plan with your utility, you could really go after that afternoon, summertime, on-peak power by lowering the tilt and even aiming the array somewhat westward. You want to produce as much of your power during the high-dollar on-peak times then at night during the off-peak hours you use utility power at a much lower rate. Most of these plans have higher rates in the summer than they do in the winter. Call your utility - they are usually very cooperative in helping you to decrease their peak loads.

    Did you tap my phone today? ComEd has a Residential Real Time Pricing program, but you end up paying an extra $23/month in fixed charges. If I offset a good portion of my electric use with solar, I would come out behind. People on the program using 5 or 600kWh/month are not saving any money, or very little. ComEd has been raising the rates in a sly manner for those folks as well. I had the same idea as you!
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