Some maintenance is needed for any technology of this type, but for PV as there are no moving parts this is typically very little. Cleaning the modules can be necessary from time to time (depending on location but typically once a year) but remember as the modules are on the roof this will most likely have to be done by a professional.

Current trends in energy prices
Government incentives

An example of a domestic grid connected PV system

Size of system 2.5kWp (roughly 18m² of roof space), retro fit, South facing no shading and located in the Midlands (based on irradiation of 850 kWh/kWp per annum)

Cost of system including all system components and installation						£10,500
Electricity generated per year						2,266kWh
FIT income from generated electricity						£981 per year
Export tariff payment (supplying electricity to the grid)						£35 per year
Electricity bill saving (assuming 50% home use, 14p/kWh)						£137 per year
Income						£1153 per year
Lifetime (25 years) income						£28,825
Annual Carbon benefit						1.2t Co2 per year

The payment for the FIT is RPI linked and the income from the exported electricity along with the savings will in effect this lifetime income. The detail of what the true return is on the initial investment needs to take into account other issues such as the cost of the money used to buy the system. However it can be seen from this example that the system pays for itself in just over 10 years. The return on investment in the first year is just over 9.9%. It should also be noted that due to the benefits the system will increase your property value.