Solar PV FAQs
1. How much electricity does a house require over the course of a year?
For a three-bedroom detached house, the figures for a standard house in the UK quoted by various organisations range from 3,300 to 3,800 kWh (kilowatt-hours) or units of electricity per annum (these may still be on the low side). It is quite possible to halve this with good energy-efficiency practices and products. For an accurate answer, as long as the meter has been read and not estimated then your electricity bill will show your own situation.
2. Do solar technologies work in the UK, even though we are not the sunniest of countries?
Yes. PV cells do not need to be in direct sunlight to work, and will generate electricity even on cloudy days. The brighter the day, the greater the energy generated.
3. Do I need to clean a PV system's panels?
No, the rainfall in this country is frequent and heavy enough to keep them clean.
4. Can I install the system to feed batteries and be independent of the grid?
Yes, but this is expensive (possibly four times the standard installed cost), so is not recommended unless cabling costs for a grid connection prove to be uneconomic.
5. What happens if there is a power cut?
If there is a power cut, your system will automatically switch off. This is a safety measure designed to stop electricity leaking on to the national grid and therefore to protect individuals who may be working to restore the power supply. It is technically possible to isolate the building from the grid to allow for continued use of the PV system, but this will add to the install costs and only be applicable during daylight hours.
6. How do the utilities know how much electricity I have exported?
Currently the trend amongst most suppliers is not to install export meters but to pay a fixed amount per kilowatt-peak installed (although there is some variance amongst the industry on this). If an export meter is required, this should not be an expensive addition. Further details on electricity export can be seen in the PV factsheet.
7. Is it okay if part of the PV panels is shaded?
No: even a small degree of shading will cause a large drop-off in performance, so shading should be avoided.
8. Are there any health and safety issues?
The key issue to be aware of is the weight of modules (some will exceed 50kg) that will need to be lifted onto a roof.
With regards to toxicity, no PV module releases sufficient toxic materials to cause any harm during installation or maintenance. Some PV products contain cadmium, the oxides of which are toxic in very small doses. Some of these may release toxic dust if crushed during incorrect disposal.