Is my roof too shaded for solar PV panels?
Posted by Chris Rudge on 14 January 2010 at 7:10 am
If you are thinking of having a solar electricity system installed in 2010 to take advantage of the last chances of getting a lump sum grant before the Feed In Tariff starts in April, the first thing to do is look for a good location to install it.
Traditionally for domestic Solar PV (photovoltaic) installations, a pitched roof is the ideal location. Look at your roof, to check that it faces somewhere between south east through south to south west.
If it does, you need to see how much open roof space there is available. Solar PV panels take up much more space than solar hot water systems. Think about 8 square metres per kWp for system size. Once you have checked you've got space, look for possible problems from shading. Gable windows and chimney stacks are probable problems you will have to consider. The array can never be shaded at any point in the day by close structures as output could drop dramatically.
Looking further away from your house, are there any trees close by or right next to the house which you know will shade the array at certain times of the day? Trees further away from the PV array can also have an impact. For example, a wooded area on the other side of the road may not block the sun during the summer, but may create shade all winter due to low sun angle in these colder months.
At best, shading issues will simply mean less production of electricity from your PV array at certain times of the day/ year. At worst, it will cause overheating in some of the cells as they try to carry electrical current from all the other modules. If damage occurs, your warranty will be invalid.
If you are unsure how affected you will be, ask an established Solar PV installer for an opinion at the same time as a quote.
Photo by Randy son of Robert
About the author: Chris Rudge is a qualified electrician who specialises in renewable energy.
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