Calculate distance between rows of panels on flat roof

[gr7]

Does anyone know how to calculate the required distance between rows of modules to avoid any shading issues? I may need to mount the panels at less than 30° to avoid the need for planning permission and would rather not use mounts such as the Solion model as these waste valuable roof space between the modules.

 

[mmccx]

can you do trigonometry?

 

[gr7]

Yes, was hoping for a 'rule of thumb' response though.

 

[JulianC]

I think I read somewhere that as a rule of thumb, row spacing should be around 3 x height of the panel at its highest point. This ties in roughly with the ConSole bucket mounts that require a row spacing of 1.2-1.5m, so if you stick to that, you won't be far wrong.

 

[mmccx]

work out the opposite and the adjacent

sin30 x hyp=opp
cos30 x hyp=adj

then muliply the opp by 1.45 to get the distance from the back of the row to the start of the next row.

and the adj * number of rows + the distatnce between a row * number of spaces between the rows = total width of the array

 

[JulianC]

then muliply the opp by 1.45 to get the distance from the back of the row to the start of the next row.

So effectively you are saying row spacing is 1.45 x height of the row. That seems far too close??

 

[jupiter276]

1. Always take a rule of thumb as Alpha = 16 degree.
2. There is also an Excel program by Schletter to calculate it. Very easy.
3. A research paper by Volker Quaschning and Rolf Hanitsch also mentioned this.
4. The book named "Planning and Installing Photovoltaic Systems
A Guide for Installers, Architects and Engineers
Second Edition" also mentioned that.
Contact me to have some more info if you want.

Jupuiter276
N

 

[Markc]

All far to complicated 3 x height works fine.

 

[JulianC]

Yup, and taking Alpha as 16 degrees as above, the distance between rows calculates out at 3.48 x row height anyway. 3 is close enough for me!

 

[Worcester]

To avoid any shading, for Reading (Lat 51.5) you should take Alpha as 15 degrees, or in simple terms, 3.73 times the height of the panels (between the top and bottom of the panel) between the back edge of the panel and front edge of the next panel

The further north you go the lower the angle gets

3 is close enough for me!

That's the equivalent of latitude 48 degrees (le Mans, France) if you do that you will get quite a lot of shading along the bottom edge of the panels which will dramatically affect output.

Just grab the Scletter Calculator, it's free and simple to use.

Oh and go here, Sunrise and Sunset Calculator

Choose something like 21st December / or look for the lowest angle, that way you can be sure of not getting shading.

 

[U2Singhy]

Can you please provide a link for the Schletter Calculator?