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Solar Panel Shadow Causes Huge Drop In Output

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  • Solar Panel Shadow Causes Huge Drop In Output

    I have the LG335N1C-V5 panels and they are working great, but there is one thing that is a bummer I wanted to share.
    Even a small shadow drops the output to nearly nothing. The picture shows a bank of 9 panels and the bottom, second from left, panel has a small shadow on it. That panel - when the pic was taken - was only producing 26 watts. The panel to the left of it was producing 194 watts at the exact same time.
    It's a disappointment that a shadow only covering about 5-10% of the panel causes a 87% reduction in output.
    I'm not sure if there are panels that will avoid this, but I wanted to share.
    BTW, once the shadow was gone from the 2nd panel the output went to 215 watts.

    Michael
    Attached Files

  • #2
    Horizonal shadows are the worst. Time to get the chainsaw out

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    • #3
      Most pv panels will drastically reduce their output if a shadow of any size crosses it's surface. Unless you can get rid of the shadow (which seems unlikely for you since it looks like a power pole) going to micro inverters for each panel will at least reduce the impact of your system.

      Unfortunately shadows and solar pv just don't mix well.

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      • #4
        If you already have a string inverter installed you could consider Tigo optimizers which are less expensive than abandoning your string inverter and replacing it with micro inverters. You don't need to add optimizers to every panel, just the ones that are affected by shadows. Either way there is no fix that won't require accessing the panels on the roof other than the chainsaw that @peakbagger suggested. That, however may need the permission of the owner of the powerpole.LOL
        Last edited by Ampster; 02-10-2020, 05:16 PM.
        9 kW solar. Driving EVs since 2012

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        • #5
          a bad situation that could have been avoided with more knowledge prior to purchase. but the peddler you bought the system from screwed you just as badly as your own ignorance.

          Readers contemplating a PV system and reading your post may learn to get informed before committing.

          One perhaps bright spot: In about a month or less, it looks like the sun will be high enough so that the power pole will not cast a shadow until maybe close to the autumnal equinox.

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          • #6
            Originally posted by peakbagger View Post
            Horizonal shadows are the worst. Time to get the chainsaw out
            I don't think the PoCo would appreciate him taking a chainsaw to a utility pole...

            Shadows are unfortunate. There are some new panels that are better able to cope with shadows, but they also tend to be a bit more expensive.

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            • #7
              I think JPMs observation as usual, is a valuable one. Depending on the location of the array the annual sun angle varies a lot from winter to summer especially the farther away from the equator the array is mounted. As the sun rises higher in the sky as the summer solstice approaches, the shadow may be less of an issue. We also do not know what time of day the photo was taken. If its outside the 9 AM to 3 PM window, the impact to total year round generation is less. In theory there should have been site survey by competent professional. This shadow issue should have been real obvious and perhaps they sized the array with extra panels to meet the house demand. Back when panels were $6 a watt shadows were big thing but when they go for less than fifty cents a watt I expect the economics works out that seasonal shadows are less of issue than they were in the past.

              Since I am in snowy climate I have to resign myself to losing production from my relatively inaccessible roof array for days at a time and if conditions are right it can be weeks before they melt off.

              The other thing to keep in mind is that new solar array owners tend to be super vigilant about system performance and some tend to be that way forever, most don't. My guess is for most people their vigilance drops once they realize that the array is an appliance and about as interesting to watch as a typical appliance.

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              • #8
                I have the same LG panels with optimizers and also have shadows from my chimney and neighbors trees. The shading was pretty bad in Dec. and Jan., but as the sun has risen higher in the sky the shadows are now a non-issue. The small amount of kWh I lose during the winter due to shading are not worth losing sleep over.

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                • #9
                  Originally posted by Ampster View Post
                  If you already have a string inverter installed you could consider Tigo optimizers which are less expensive than abandoning your string inverter and replacing it with micro inverters. You don't need to add optimizers to every panel, just the ones that are affected by shadows. Either way there is no fix that won't require accessing the panels on the roof other than the chainsaw that @peakbagger suggested. That, however may need the permission of the owner of the powerpole.LOL
                  I was going to suggest this. Tigo makes amazing products, and their optimizers are specifically designed to resolve problems like this. Check this video out: they explain it in great detail
                  https://www.youtube.com/watch?v=XvUNETwfkhE

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