Location & Siting
PV panels need to be sited to get the most exposure to sunlight as possible while avoiding being in shadow. It is best if they are south facing and at an optimum angle to get the most sunlight. Even if not directly south facing they work reasonably well southeast or southwest facing.
PV panels are usually located on the roof of a building. But there are various siting options:
1. Roof-mounted: on top of the roof
2. Roof-mounted: within the roof
3. Wall-mounted
4. Ground-mounted: fixed
5. Ground-mounted: Solar Tracker
6. Building-integrated photovoltaics
1. Roof-mounted: on top of the roof
In a pitched (sloped) roof, the panels can be fixed to a steel frame that lies just above the external face of the roof (ie. above the roof tiles or roof slates). For structural support, the steel frame can be fixed to the rafters of the roof and/or to the gable wall. Panels can be sited this way on existing pitched roofs (retrofit) or on new pitched roofs (new build). Having the panels above the roof is often preferable in an existing roof as it avoids the sometimes distruptive work of removing all roof tiles/slates under the panels.
In a flat roof, the panels are also fixed to a steel frame for support. The steel frame is built so that the panels are at the best angle to get the most sunlight. The steel frame is fixed to the roof structure and/or the wall structure (such as a side wall, an upstand or a parapet) for structural stability. Panels can be sited this way on existing flat roofs (retrofit) or on new flat roofs (new build).
2. Roof-mounted: within the roof
In a pitched (sloped) roof, the panels can be located within the roof so that the panels are flush (level) with the external face of the roof (ie. above the roof tiles or roof slates). Panels can be sited this way on existing pitched roofs (retrofit) or on new pitched roofs (new build). Having the panels within the roof is often avoided in an existing roof as it requires the sometimes distruptive work of removing all roof tiles/slates under the panels. It does make good sense in a new roof where the roof tiles or slates can simply be installed around the panels. This reduces the amount of roof tiles or slates needed which saves money.
3. Wall-mounted
When panels are fixed to a wall a steel or timber frame is used. The steel frame is built so that the panels are at the best angle to get the most sunlight. Panels can be sited this way on existing walls (retrofit) or on new walls (new build). Timber frames need to be treated with preservative. The wall will need to be south facing for best results.
4. Ground-mounted: fixed
When panels are located on the ground a steel or timber frame is used for structural support. The steel or timber frame is built so that the panels are at the best angle to get the most sunlight. For best results, the panels will need to be south facing and located so that they avoid being in shadow. Ground-mounted panels are more likely to be in shadow (because they are low lying) so care must be taken that obstructions to sunlight are minimised. The most common obstructions are walls, hedges and neighbouring houses. Also, there will need to be enough open space to the south of the panels so minimise shadow. Timber frames, if used, will need to be treated with preservative. Panels can be sited this way beside existing buildings (retrofit) or beside new buildings.
5. Ground-mounted: Solar Tracker
A solar tracker is a device for automatically turning a PV panel so that it faces directly into the sun. More electricity will be generated if the panel is directly facing the sun as it will be exposed to greater sunlight. Trackers use motors and gear trains to orientate the panel so that it follows the sun all day as it crosses the sky from sunrise to sunset. A fixed system that doesn't follow the sun will generate less electricity.
6. Building-integrated photovoltaic
Building-integrated photovoltaics (BIPV) are photovoltaic materials that are used to replace conventional building materials in parts of the building such as the roof, windows or facades. Building elements such as roof tiles have integrated photovoltaic cells which like other photovoltaic technologies convert sunlight into electricity. Building-integrated photovoltaics are sometimes the main source of electrical power in the building but they usually supplement the grid supply. They can be installed in new or existing buildings. The main advantage of integrated photovoltaics is that money is saved because they replace conventional building materials. Also, since BIPV replace conventional building materials they generally blend in better and are more aesthetically appealing.