In order for a PV installation to be cost effective the following factors should be considered:

• A suitable area of at least 10m2 is available
• The area to be covered should not be shaded by other buildings or trees
• The most effective roofs face between south-east and south-west.
• Solar panels do not usually need planning permission if they are not on the roadside of the house, do not project beyond the roofline and are not in a conservation area or on a listed building. However, it is prudent to contact your local planning authority to ascertain if they require planning permission.
• What type of photovoltaic system would be suitable?

Photovoltaic modules can be placed on almost any building surface that receives sunshine for most of the day. Roofs are the usual location for PV systems on houses but photovoltaic modules can also be placed on facades, conservatory or atrium roofs, sun shades, etc.

If a PV installation is being considered as part of a new build programme, or during scheduled roof repair, then the use of a system designed into the building (Building Integrated) such as roof tiles could be considered. These systems effectivly replace the building material i.e. tiles, glass or cladding on a like for like basis but have the added benefit of producing electricity. Building integrated systems generally have a shorter payback period, as the cost of system is effectively only the difference between conventional building products and solar ones.

However, if the roof is not being re-done then modules mounted on the existing surface (a bolt-on system) are probably the most cost effective option. These systems sit on top of the existing building materials on a bracket or mounting system. Most systems do not sit flush with the roof line. These systems are generally cheaper to purchase and can be installed relatively simply with little inconvenience to the building occupier. 

Generally the balance of system components (the wires and the inverter) will be housed in the loft space of the building. To minimise losses through the system the systems are often designed to house the inverter as close to the PV system as possible so that the power can be converted to AC near to the point of generation. Wiring will then taken to the main distribution box and the power will be synchronised with electricity demand from the grid.