Can a PV system be installed on my building
The most important questions to consider in deciding whether or not a PV system can be installed on a building and what type of system should be installed are:__________________
- is there a suitable place on the building where the solar array could be mounted (taking into account orientation, shade, and available area)
- what type of photovoltaic system would be suitable
- is planning permission required Photovoltaic modules can be placed on almost any building surface which 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.
The surface on which the PV array is mounted should receive as much light as possible. The more light the solar array receives the more electricity will be generated. The three issues which affect how much light a surface receives are:
1. Orientation: Due south is the best possible orientation. If the PV is to be mounted on a vertical façade the orientation should preferably be between South East and South West. If the PV is to be mounted at a tilt a wider range of orientations will still give a reasonable energy yield. North facing orientations should be avoided.
2. Tilt: A tilted array will receive more light than a vertical array. Any angle between vertical and 15o off horizontal can be used. A minimum tilt of 15o off horizontal is recommended to allow the rain to wash dust off the array. The optimal tilt angle is 30o - 60o for a south facing array in Europe. Shallower tilt angles are better for east or west facing arrays.
3. Shadowing: Shadows cast by tall trees and neighbouring buildings must also be considered. Even minor shading can result in significant loss of energy. If shading is unavoidable, your system designer can advise on how to minimize the effect of shade on the amount of electricity produced.
The area required for mounting a PV array depends on the output power desired and the type of module used. An area of around 8 m2 will be required to mount an array with a rated power output of 1kW, if monocrystalline modules are used (the most efficient modules type). If multicrystalline modules are used an area of around 10 m2 will be required for a 1kWp system and if amorphous modules are used an area of about 20 m2 will be required. These areas can be scaled up or down depending on the output power desired. 1 - 3 kWp is a typical power output for a domestic system, although smaller or larger systems can be installed.
There are various ways in which a PV array can be mounted on a building. The various options offer different appearances and vary in cost. The commonest way of mounting an array on a house is to place it on the roof either with modules mounted in a frame above the existing roof tiles or integrated into the roof. If the array is to be integrated into the roof PV roof tiles may be used instead of modules.
PV arrays can also be mounted on flat roofs, on walls, in conservatory roofs, on sun shades or on other structures such as pergolas or car parking bays.
PV roofs do not usually require planning permission unless the building is listed or in a conservation area. However you should call your council to check on local policy.
How much electricity will a system generate?
A system with a PV array tilted towards the south would generate approximately 750/1500kWh/year per kWp installed (in Europe). So a typical 2 kWp system (around 20 m2 of multicrystalline modules) would generate around 1500/3000 kWh per year. Output will be reduced by shade or non-optimal orientations or tilt angles.
How much will a system cost?
A typical price for a grid connected, building integrated PV system is between Euro 6 and Euro 7 per Wp, this works out at Euro 12.000 - Euro 14.000 for a 2 kWp system for a house.
There are a number of factors that will influence the cost of a system:
· Whether or not the system is being installed while the building is being built or as a retro-fit to an existing building. If the system is being installed on a new building some savings may be made, eg the number of roof tiles that need to be purchased could be reduced.
· The number of PV systems being installed at a time. A house builder installing systems on a group of houses can expect a price nearer the bottom of the quoted range than an individual householder.
· The size of the system being installed, a larger system may be cheaper per kWp while a small system may be more expensive.
· How difficult or easy it is to access the area where the PV system is being installed. The typical price quoted applies to installation on a typical house roof, if the roof is a complicated shape or requires complicated scaffolding costs will be higher.
· The module type used will significantly impact on the costs. The typical price quoted is based on standard modules, tile type systems are somewhat more expensive. The most expensive systems use semi-transparent glass modules in facades or conservatory roofs.