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Solar Panel Direction for best PV production


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Hello.. I want to install 14 panels however I only have space for 8 in the N direction and 3 in the NE and 3 in the E. 

My question is those that are placed in the NE and E direction.. Typically what time would PV production start and for how long? 

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Assuming 35 degree roof angle and Cape Town:

Yield on 1 July

image.png.492ac9a51a6bcc4bc6d71d647120ccca.png

 

Yield on 1 Jan:

image.png.72585718b05efe2ad81b039625c419a9.png

Essentially, in summer not much difference.  in winter the East facing panels (red line) do very poorly.

The actual numbers change a lot with different roof angles and locations, but you get the general idea.  If you supply your location and angle I can rerun the graphs.

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Thank you for the response, so I assume the black is North and the dark red is NE? Attached my location. When u say 35 deg roof angle you mean the roof or the actual angle of the panels when installed? Also assume JHB please IMG_20220508_082105.thumb.jpg.526759d8ac3fef64f68fe77b8cb750c3.jpg

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11 minutes ago, Solarcrazy said:

When u say 35 deg roof angle you mean the roof or the actual angle of the panels when installed

The actual panel inclination is needed.

 

12 minutes ago, Solarcrazy said:

I assume the black is North and the dark red is NE

The legend is at the top: 0/35 means North, panel inclination 35 degrees, 45 means NE, 90 means East

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@Solarcrazy You can use Solcast to give you a fair forecast for three days in advance with their free service https://solcast.com/
All documentation is available on their site.  https://articles.solcast.com.au/en/articles/2979582-getting-started-with-rooftop-pv-sites


Here is the past three days actuals and the next three days forecast that they provide for my specific location input. And this is for Johannesburg.
image.png.5f6fac26b05c35e69da15002584fc587.png
 

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Posted (edited)
7 hours ago, Solarcrazy said:

Hello.. I want to install 14 panels however I only have space for 8 in the N direction and 3 in the NE and 3 in the E. 

My question is those that are placed in the NE and E direction.. Typically what time would PV production start and for how long? 

Well it would depend on where you are. I'm in Randburg with 6 panels facing N and 6 facing E. I start getting PV about 7:00 this time of year, something useful just after 7:30, peak PV power about 11:30, and as late as 14:30 I am getting about 30% of PV from the E facing array.

Edited by Bobster
sppeling
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6 hours ago, zsde said:

@Solarcrazy You can use Solcast to give you a fair forecast for three days in advance with their free service https://solcast.com/
All documentation is available on their site.  https://articles.solcast.com.au/en/articles/2979582-getting-started-with-rooftop-pv-sites


Here is the past three days actuals and the next three days forecast that they provide for my specific location input. And this is for Johannesburg.
image.png.5f6fac26b05c35e69da15002584fc587.png
 

Thank you.. Looking into it 😁

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I've seen panels on some of the buildings at Route 21 Business Park in Irene , Centurion mounted on all 4 sides of their roofs ( buildings with 4 sided roofs E,W,N,S). Just to add that these buildings have no trees or other buildings blocking the roofs and are on a hillside with tons of sunshine the whole day.

 

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The research I have done shows not significant difference in daily production (give or take up to 15%) irrespective of facing and inclination through the arc east, north to west provided no shading. Certainly east will provide power sooner with the morning sun and likewise west in the afternoon but if the battery is right sized, it will matter less. My panels are just off north and in full sun all day (roof inclination 25 deg). I'm in East London and typically see production peaking from around 11:30. What has been noticable is the production fall off (as much as 25%) now in May compared to February when my system got installed.

My advice, do not be to hung up on facing, try and avoid shading.

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13 minutes ago, Peter V said:

The research I have done shows not significant difference in daily production (give or take up to 15%) irrespective of facing and inclination through the arc east, north to west provided no shading. Certainly east will provide power sooner with the morning sun and likewise west in the afternoon but if the battery is right sized, it will matter less. My panels are just off north and in full sun all day (roof inclination 25 deg). I'm in East London and typically see production peaking from around 11:30. What has been noticable is the production fall off (as much as 25%) now in May compared to February when my system got installed.

My advice, do not be to hung up on facing, try and avoid shading.

Thank you 😁

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1 hour ago, Solarcrazy said:

Thank you 😁

I agree , although my west facing string is weaker than north facing at their peaks . In Feb they actually punch above their nominal weight  , in May I also experience considerable less performance . But my angle is only 18% , that's bad , good for midsummer but especially bad for this time of year. 

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