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I'm thinking of getting solar PV, but the main house has a hotchpotch of small roof spaces, so unsuitable. But I do have a large double garage, with flat roof, in an unshaded area. For the life of me I can't find a calculator, to give me an idea of how many I could reasonably fit. Anyone know of one?
They are around 1.65m x 1m each per 250w panel if that helps. Maybe draw a picture?
What size is your roof?
Jeff
Ikea's site?
If you're looking to calculate how much you can generate try:
http://www.energysavingtrust.org.uk/scotland/tools-calculators/solar-energy-calculator
For a flat roof this may help
https://www.spiritenergy.co.uk/kb-flat-roof-solar-mounting#
Laying them flat isn't a good idea, they need a slope to keep leaves etc off.
You would want to angle them to face South.
Also, consider that no matter what size your roof, normally you are limited to a 3.7kw array if you only have the usual single phase electric supply.
You can of course ask nicely for a larger connection size, but it may not be free.
pvwatts seems a good estimator site - got a client's of mine to to within 0.2%
The roof is just a bit bigger than 4m x 6.5m. And is broadly north-south.
All the calculators assume you have a pitched roof. The sprint energy site is interesting, and shows some very low angle installations. But then doesn't give a calculator for flat. Obviously the lower the angle, the more you can fit in a given space without shading the ones behind.
But then doesn’t give a calculator for flat. Obviously the lower the angle, the more you can fit in a given space without shading the ones behind.
You are better off tilting them
At them measurements you would be looking at 12 x panels, 2 rows of 6 Most are now at 285w per panel but you can get 327w, but the price per panel is a lot higher for the 327w so may not be financially beneficial. You need to try an get even a slight pitch on them to stop them being covered in dirt all year round, but the higher the pitch better the performance. If you could get a 10 degree pitch 12 x 285w would get you in the region of 2500kw per year off the top of my head.
With flat roofs you need to limit or remove the shading on row 2 from row 1. roughly allow 1.5 times the height of row 1 for the gap between the rows. at only 4m in total you don't have this option so look at solar edge or similar where the panels work individually rather than as a block of panels.
i would go for 300w JA Solar solar panels with the built in Solaredge optimisers and a Solaredge HW wave inverter. Mounted on Tric F Box ballasted flat roof system. Look to pay about £5k inc VAT. i would say approximately 3000kWh / year solar generation.