Production down from summer heat?

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gtojohn
gtojohn Registered Users Posts: 20 ✭✭
in Grid Tie and Grid Interactive Systems #1
I have a small 6 panel 1.4 kw array with enphase m215 inverters. Its only been in use since May. We've had a mild summer but in the last week we started hitting triple digits here. Previous month I'd average 9-9.6kwh a day. This past week I'm getting closer to 8.0. Could this be the heat causing inverters or panels to clip? I don't have the envoy, just monitoring with a stand alone induction style power monitor. Need to get my ladder back from a neighbor to check panels for bird poop.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #2
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    Yeah it happens every year at this time here, production slides due to heat.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #3
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    Probably... You can get a ~3% drop as new panels "age/burn in" during the first 6 months.Another 10% drop due to high temperatures (and dust/bird droppings) is certainly possible.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
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    A couple weeks ago, I was down 30% from nameplate, from +100F heat and no breeze, but they are cranking today
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #5
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    If you have a mono panel there will be a significant loss in power due to the heat.
    Polys tend to hold up a little better to heat.

    95* weather it is common to see a 2.5% drop in peak power, roughly 1.25% from the solar panels and 1.25% from micro inverter.
    If you have soiling from not cleaning the panels for 3 months "minimum" that is roughly another 2.5% drop.

    System performance could be affected by up to 5% ptc which could have the system harvesting between 98%~101%, monthly harvest.

    Half of the systems I am monitoring in California due to the drought (soiling), and the heat wave is causing the systems to operate between 93% and 98% daily, which is normal under PTC.
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  • gtojohn
    gtojohn Registered Users Posts: 20 ✭✭
    #6
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    Probably more the heat, its been over a hundred with no wind. I gave them a good wash. Despite heavy rains in June my panels had a thin layer of dust, tree sap and bird poop. Windex dried before I could wipe them clean. I ended up using a 1 gallon sprayer and a mop. I'm considering next time using something like prestone bug and tar windshield cleaner. Any other recommendations on cleaning?
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  • SolarPowered
    SolarPowered Solar Expert Posts: 626 ✭✭✭
    #7
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    gtojohn wrote: »
    Probably more the heat, its been over a hundred with no wind. I gave them a good wash. Despite heavy rains in June my panels had a thin layer of dust, tree sap and bird poop. Windex dried before I could wipe them clean. I ended up using a 1 gallon sprayer and a mop. I'm considering next time using something like prestone bug and tar windshield cleaner. Any other recommendations on cleaning?



    Do not use detergents on panels if you have A/R coating.

    It should be as simple as just using a micro fiber sponge and a bucket of water, do not use a pressure washer as it can blow out the seals to the frames.
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  • verdigo
    verdigo Solar Expert Posts: 428 ✭✭
    #8
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    My summer production has fallen off as well. Humidity (more haze) makes a  big difference vs low humidity days. Overall my net production is better in summer but I do better on a clear winter day even with shorter hours than a clear but otherwise hazy day.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #9
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    SolarPowered wrote: »



    Do not use detergents on panels if you have A/R coating.

    It should be as simple as just using a micro fiber sponge and a bucket of water, do not use a pressure washer as it can blow out the seals to the frames.
    And do not apply cold water to hot frames. Clean first thing in the morning or late in the evening.

    SMA SB 3000, old BP panels.
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