Flat solar panels?

waqasahmed

Hi

So I've requested planning permission for 8 solar panels on my flat roof. I've been advised that there are no issues with 6 of the panels at the rear dormer, but the two at the front would either need to be removed or laid flat. This is because the council bvelieves that the panels at the front would visually affect the streetscape

Would it be fine to have solar panels, laying flat? Or would it be best to just ask for six panels instead of 8? I've already got 8 panels on my non flat roof fwiw anyway

pramsay13

It will be less effective if it is flat so you will need to ask your installer to do some calculations to see if it is worth it. 
It will depend where you are in the country and the orientation of the roof. 

Reed_Richards

Can you mount the non-flat panels on a turntable that can rotate so the panels always face the sun?  That would compensate for the two other panels, I would think. 

1961Nick

I'd get the 6 most efficient panels I could buy & forget about the flat panels. 

zeupater

Hi

Flat panels need cleaning all the time as any build-up of dust/dirt/bird droppings just doesn't get washed off with regular rain ... even in downpours it tends to build up in whichever area is lowest ... maybe you could get away with very slight slope, but even then you'll only be reducing the issue, so it really comes down to how accessible the roof is for cleaning.

(Experience - I tried a small flat mounted DC setup about 15-20 years ago, the pigeons & ducks loved it's welcome heat!)

Not long after the UK FiT scheme came out I talked to someone with a flat roof where the local authority were only really concerned with the flat panel aesthetics and allowed a small panel slope as long as it didn't extend any part of the new structure above the parapet wall, I guess that they considered this as being the equivalent of the ridge-line on a standard roof .... anyway, it seems that he was experiencing performance loss for the very same reason I had found a number of years earlier, but had no problem getting onto the roof, so simply accepted that a ~monthly cleaning schedule was normal ...

I'd tend to go with 1961Nick's solution, but say panels with the greatest rated power that you can fit in the allowable space as opposed to pure efficiency as that's what counts, you could also talk to the installers about their view on bifacial panels and possibly lightening the roof colour (reflective) below the panels, but it's likely that it wouldn't make that much difference in the scheme of things .... but buy a water-butt, a good ladder/bucket/sponge & squeegee and be prepared to use them!

A ~460W bifacial panel would be approx 2.1x1 metres and likely be ~21% efficient if that's useful ...    

HTH - Z

matelodave

You'll get a dramatic fall off in performance between autumn & spring due to the low angle of the sun but probably not so much in high summer when the sun is at it highest - have a look here to do some quick calcs to see whether the loss of performance outweighs the cost of the panels - https://re.jrc.ec.europa.eu/pvg_tools/en/