Photovoltaics (PV) panels use rays from the sun to produce electricity. The best performance, in terms of electricity production, is achieved with direct sunlight, however the panels still operate under poor weather conditions and can be used in the British climate.

PV panels are manufactured in three basic types:
1. Fixed panels in aluminium frames of various sizes and outputs up to a one square metre panel, producing 64 watts.
2. Flexible panels that can be moulded into different shapes.
3. A building integrated system, in the form of a roll of plastic which when installed on a roof gives the appearance of "Welsh slate".

Electricity is produced in Direct Current (DC) mode and requires an inverter to enable the power to be used for domestic and commercial appliances. It is customary to incorporate battery storage and a charge controller as an integrated part of the system.

Advantages

· Solid state, low maintenance, under warrantee for 20 years.
· Will provide off grid power solutions.
· Buildings integrated PV can substitute or partially substitute for alternative materials costs.
· Can form part of a solution to provide un-interrupted power supplies (valuable to some businesses).

Limitations

· Unreliable power supply - in most applications, PV would need to be installed in conjunction with other technology (e.g. wind)
· Low power output (nominally 60 watt per square metre).
· Required to be installed south facing and inclined at between 30 and 45 degrees.
· Average UK performance of 4.5 hours per day.
· Can be the target of theft (reasonable resistance to vandalism).

Costs

· Estimates range between £4 and £7 per watt installed.
· Currently £20M of grants available for commercial, domestic and local authority installations.
· 10 years plus payback period, unless installation can be attributed with avoided building costs

Applications

· Part of hybrid un-interruptible power supplies (e.g. doctors' surgery, computer businesses)
· Remote power for road signs (use of "keep left" bollards avoids digging up roads for cables) and bus shelter proximity lighting.
· Car ports
· Covered walkways
· Architectural features, e.g. to power display lighting or fountain pumps.