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Solar Photovoltaic (PV)
Last Post by batalto 3 years ago
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 PiersA
(@piersa)
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Topic starter 07/10/2021 5:13 pm  

I am looking at a new housing development behind us and two out of the six houses have got their solar panels mounted on the north facing side of the pitched roof! It would have been perfectly possible to fix them on the south facing sides which indeed would be basking in sunshine most of the day! What reduction in performance can the home owners expect, quite considerable I would imagine as the panels rely on reflected sunlight off the sky rather than directly receiving photons from the suns rays. Does anybody have experience of this scenario or can quote output figures vs orientation? Thanks


   
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 Derek M
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07/10/2021 6:03 pm  
Posted by: @piersa

I am looking at a new housing development behind us and two out of the six houses have got their solar panels mounted on the north facing side of the pitched roof! It would have been perfectly possible to fix them on the south facing sides which indeed would be basking in sunshine most of the day! What reduction in performance can the home owners expect, quite considerable I would imagine as the panels rely on reflected sunlight off the sky rather than directly receiving photons from the suns rays. Does anybody have experience of this scenario or can quote output figures vs orientation? Thanks

Hi PiersA,

Unless you live South of the equator, it is quite pointless mounting solar panels on a North facing roof. Whoever decided it would be a good idea to do so, must be living in an alternative universe.


   
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 batalto
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08/10/2021 8:23 am  

Just use this tool - https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html

For my system (8.4kw) I can expect 9.2MW per year (facing south). Facing North, I would expect 4.7MW

So facing North, you can expect roughly half the power production

 

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 PiersA
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Topic starter 08/10/2021 9:36 am  

@batalto - thanks so much! I will check out the tool. I had estimated a 45% reduction. I look forward to meeting the home owners and pointing out to them and the potential losses over the life of their house! Whether they can do anything to get the builder to put them on the other South facing side or do anything under the NHBC guarantee? Cheers 


   
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 batalto
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08/10/2021 9:43 am  

@piersa if you assume its a 4kw system (which is the max size) you'll be losing half your feed in (whatever that might be)

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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