Photovoltaic panels (known as PV cells) convert sunlight into electricity. Many people find them visually attractive, and in an effective installation, they can demonstrate commitment to sustainability.

 

Photovoltaic materials are usually solid-state semiconductors which generate electric current when exposed to light. Panels are available in a variety of glass-based packages, including traditional aluminum framed panels, plain cladding, solar roof tiles and custom built glazing with integral PV cells.

 

Site suitability

 

PV cells are most effective in bright sunlight but are still able to produce some limited power in the UK on cloudy days. A PV system will not meet the entire electricity needs of a business, but could provide a significant percentage.

 

New-build sites are ideal for PV installations because architects are able to design the system to be truly integrated, for example, as roof tiles.

 

Retrofitting PV cells to existing buildings is also an option. However, the building must first be surveyed to ensure that it is able to take the additional load. This will incur an additional cost when compared with new-build, which must be taken into account along with installation costs. PV cells should be installed so that they are oriented in a southerly direction to face between south-east and south-west. They should be installed in an unshaded area and tilted at an angle of around 30-40º to the vertical  for optimal performance. Planning permission is not usually required for small-scale PV installations. However, there are exceptions (for example, on listed buildings). Businesses should always contact a planner at their local council for advice before proceeding.

 

Costs and payback periods

 

As a rule of thumb, the average output from a 1 kW peak solar cell in the UK is 700-850 kWh/year.

 

Maintenance costs for the cells are low and generally only involve cleaning the panels.