23 minutes ago, Dreadnaught said:

 

I am interested in the angle of those trays.

 

It says "Yield optimised system with an angle of 15° for minimum distance between rows".

 

My initial guess was an angle of 52º or higher would have been better given the maximum azimuth of the sun in the UK but I now see that panel-to-panel shadowing could be a major issue on a flat roof.

 

Thoughts anyone?

 

I was thinking on those lines. Steeper the angle the greater the spacing needs to be to avoid shadowing.

5 hours ago, JSHarris said:

The thing with RHI is that it depends on the assessed requirement, so if you build a well-insulated, low energy house then you get less RHI.  The worse the house is, the more RHI you get.

 

On the website https://www.uvalue-calculator.co.uk/calculator/flat roof/warm flat roofing/single ply/fully adhered/concrete deck with plasterboard ceiling/145/

it looks like size /type of property + number of bedrooms are a big factor as presumably more bedrooms = theoretical higher DHW needs due to more people. My info seemed to reach the cap in payments but maybe the proper EPC will bring that down as the calculator didn't seem to have a way to accurately input insulation