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  1. #1
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    Solar panel allowable mounting overhang

    Hi All, I have a small array of four panels on my roof each 1640x992x40mm, they are supported by two horizontal rails each secured to the roof timbers with three heavy duty brackets and long screws.

    My problem is in winter when the sun is low a telephone cable that flies across my property causes a shadow just visible in the picture about 1.5 cells up from the bottom across the entire array causing a fair amount of lost power. I have verified this by weighing down the cable to remove the shadow and the output goes up maybe 10%.

    I do not want to move the mounting rails as this would entail removing and re-installing all the panels and it was a hard job getting them up there in the first place, I am however considering moving the panels up on the existing rails about 1.5 cells, this would still leave the bottom firmly clamped BUT the top overhang would increase from the present 1.5 cells to ~3 cells. Panels are Axitec AC260P/156-60S

    I cannot find any information anywhere as to whether this is permissible, does anyone have any ideas/experience they could share please ?

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  2. #2
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    Re: Solar panel allowable mounting overhang

    Quote Originally Posted by fourtytwo View Post
    Hi All, I have a small array of four panels on my roof each 1640x992x40mm, they are supported by two horizontal rails each secured to the roof timbers with three heavy duty brackets and long screws.

    My problem is in winter when the sun is low a telephone cable that flies across my property causes a shadow just visible in the picture about 1.5 cells up from the bottom across the entire array causing a fair amount of lost power. I have verified this by weighing down the cable to remove the shadow and the output goes up maybe 10%.

    I do not want to move the mounting rails as this would entail removing and re-installing all the panels and it was a hard job getting them up there in the first place, I am however considering moving the panels up on the existing rails about 1.5 cells, this would still leave the bottom firmly clamped BUT the top overhang would increase from the present 1.5 cells to ~3 cells. Panels are Axitec AC260P/156-60S

    I cannot find any information anywhere as to whether this is permissible, does anyone have any ideas/experience they could share please ?
    I think you need to ask the manufacturer this question. Personal opinions don't mean much when it comes to product warranties. Looking at the axitec installation guide it recommends 250 to 350 mm from ends of long side of panel. At 4 or 8 symmetrical quarter points.


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  3. #3
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    Re: Solar panel allowable mounting overhang

    Ohh thank you, I was only looking at the product spec sheet and it was not clear from there.
    As it happens I also found later in the day the shadow moves beyond this fix but useful information :)



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  4. #4
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    Re: Solar panel allowable mounting overhang

    If just one of the cells' impedance goes up a lot then panel output drops severely. The shadow's effect may change if you rotate the panels 90 degrees. It could change the pattern of impedance created in cells, and so it might reduce overall impedance.
    I'm not sure how this effect compares in crystalline panels versus amorphous type versus thin-film type.


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  5. #5
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    Re: Solar panel allowable mounting overhang

    I will start a new thread about this as it is unrelated to overhang but thankyou :)



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