Solar PV Site Selection

PV arrays can be mounted in a range of locations but the roof of a building usually provides the best and simplest site.

Size: The physical space available needs to be considered. For example, a 1kWp PV array will occupy at least 8m² of roof. Positioning an array too close to the edges of a roof may compromise the aesthetics of the installation and has implications on wind loading.

Orientation and pitch: The ideal site is one that faces south with a slope of around 30-40°. However, as can be seen from the table below, other orientations and pitches can be viable with relatively little drop in performance

Shade: Any shade, such as from trees or neighbouring buildings, can make a large impact on the performance of a PV system. To work effectively, the whole PV array needs to be free from shade for the majority of the day.

System sizing

PV systems are modular, allowing a great degree of flexibility in design and specification. In practice, the size of a system is often determined by the available roof space. Alternatively, systems may be specified to meet a CO2 or energy generation target, or budgetary constraints.

PV arrays are sized in kWp (kilowatt-peak), the rated output under standard test conditions.

As a rule of thumb, an optimally orientated, un-shaded 1kWp array will, each year, generate approx 750kWh (units) of electricity and save approx 0.4 tonnes of CO2