Monday, 4 January 2010
PV shading thoughts.
If you are thinking of having a solar PV 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 installations, a pitched roof is the ideal location, being up high and out of the way from most obstructions... Looking at your roof, are you able to check off that it faces somewhere between South East through South to South West?
If yes, you need to see how much open roof space there is available. Solar PV takes up much more space than Solar Thermal systems. Think about 8 square metres per kWp for system size. Once you have ascertained you've got space, look for possible problems from shading. Gabled windows and chimney stacks are probable issues and you will have to consider the array can never be shaded at any point in the day by close structures as array output could drop and cause loading on some of the shaded cells.
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 could 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 be in shade all winter due to low sun angle in these colder months.
For the PV array, shading issues at best will simply mean less production of electricity at certain times of the day/ year, or at worst will cause overheating in some of the cells as they try to carry electrical current from the other modules. If damage occurred, your warranty would be invalid.