flat roof pv install - distances from edge & suitability?

[robbiemeek]

I have a flat roof installation SW facing 5.5m accross and 7.4 back, felt covered.

I obviously want to provide the max array output possible taking into account shading distances between etc.

The roof is 5m high, a loft extension to bungalow, and I don't want to overload the roof with tonnes of ballast etc.

This looked good to me - http://www.solion.co.uk/docs/SunMountweb.pdf

Anyone used it?

what min distances from the edge should I allow for?

Anyone got any better ideas?

thanks

 

[xanderfh]

Did you get any response from your post, as ive got a flat roof to quote and would like to know the distance from the edge of the building panels are permitted to be.

 

[TedM]

You may need planning permission for that, depending on the various heights and angles involved.

 

[xanderfh]

I did think that, but for an initial assesment I would like to give the customer a rough idea of how many panels can be installed on there roof (subject to planning) On PVSol the optimum angle for location is 36% so I have worked out spacings using trig and 3X rule of thumb for spacing - just need to know recommended dist from edge - did see some where it depends on height of building?

 

[jupestar]

If you shunt them up to 36deg, you'll require one hell of a lot of ballast for the panels, give your structural survey a chance bring them down to 20/15, the KWh/KWp will go down but you'll get more capacity on. Plus mounting kits are easier to get for the lower inclinations.

 

[robbiemeek]

according to solaron - stated:
You must keep in mind the minimum edge distances as stated in the European wind loading manual.
This minimum edge distance is 1/5 of the height of the building from the edge and ½ the height of the building from the corners.

The minimum edge distance is set in the European wind loading standard for flat roofs. It applies for any non-secured systems on a flat roof.
It applies here because the system does not penetrate the roof membrane to fix to the structure of the building.

This greatly reduces the available area and array size - so I was looking for any alternatives?

 

[funkyferg]

Hi,

Is there an easy guide of calculating how many pv panels you can get on to avoid shading from the panel in front at different degrees? Basically I have a roof 21m x 12 m and want to max the amount of panels on this. Any suggestions?

Cheers

 

[whinmoor]

We used this calculator to help us when doing something similar: Solar Mounting Systems and Solar Structures from RBI Solar Products

Lots of extra issues to consider with this type of installation including - roof strength, ballast, wind strength, landscape or portrait, angle of inclination, accessibility, perimeter protection, planning, skylights, etc etc.

HTH

 

[John Allen]

Why not consider lying them flat on the roof, run it through PV Sol and see the difference in yield betweeen the option of flat and at an angle of 15 or 20 degrees

 

[taffbutc]

This has been an issue for a while. Depending on what course you do depends on what you are told. The new DTI which i have been told will be out shortly will have in in black and white to avoid confusion. (I believe it will be 300mm). You must remember though that it must be structural safe and remember to do your wind calculations.

Taffy

 

[FB.]

Why not consider lying them flat on the roof, run it through PV Sol and see the difference in yield betweeen the option of flat and at an angle of 15 or 20 degrees

In many cases, that would seem to be the easier option as even a small tilt angle can require a very big increase in panel spacing in order to avoid shading.

I'm not so sure about completely flat panels, though, as they would tend to get dirty more easily and come clean less easily.
I thought that a minimum of about 15 degrees tilt on a flat roof was required in order for the panels to be reasonably self-cleaning.

 

[Worcester]

There are various panel mounts like the TricF Box that make the small angle uplift simple to do - never mount them flat - they should be at aleast at 5 degrees Wagner Solar, solar power systems, solar heating sytems, solar collectors - TRIC F box NEW!