There are various ways in which a PV array can be mounted on a building which 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.

The main points to remember when designing an installation are:

• Thermal Expansion - the fixing must allow for thermal expansion without breaking the glass. Weather sealing involves standard construction practices but all materials must be suitable for high temperatures (i.e. temperatures at the back of the modules can rise to 80ºC if they are poorly ventilated or higher if they are directly insulated).
• Maintenance - the mounting option must allow for safe maintenance and possible replacement of individual modules. 
• Support structure – the life of the support structure must be at least that of the PV array. The preferred materials are aluminium, stainless steel or glass-fibre. Protection from corrosion is important especially as residual electrical currents may be present.
• Wind loading
• Any extra weight
• How and where to run electrical wiring - this may penetrate the waterproof skin.
• Where to place junction boxes

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 that 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 - 40º for a south facing array in the UK. Shallower tilt angles are better for east or west facing arrays. In addition tilting the array means that the system is naturally washed by rain water and does not require additional cleaning. 
3. Shadowing - Shadows cast by tall trees, neighbouring buildings, lamposts etc must also be considered. Even minor shading can result in significant loss of energy. If shading is unavoidable, the system should be designed to minimise 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 8m2 will be required to mount an array with a rated power output of 1kW, if mono-crystalline modules are used (the most efficient modules type).

If multi-crystalline modules are used an area of around 10m2 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.

Home systems for generating electricity can be fitted by professional installers in as little as one day.

• Planning issues

Planning permission is not normally required for a solar PV array if the panels do not project significantly beyond the roof slope. However, exceptions may apply for systems on listed buildings or in areas of outstanding natural beauty.

It is advisable to contact the local planning department prior to any installation to check on local policy.

• Connection issues

PV modules generate DC electricity before an inverter converts electricity to mains quality AC. As DC wiring is not the norm in domestic buildings, awareness of the different wiring requirements is needed.

It is essential that the connection of all distributed PV generators to the electricity network is approved by the relevant Distribution Network Operator responsible for the network. Before installing a grid connected PV system it is important to ensure that the following approvals have been received:

• Permission from your local Distribution Network Operator (DNO) to connect to the electricity grid.
• Approved equipment for use within the UK, notably inverters.

These are mandatory requirements, largely to ensure that distributed grid-connected generation systems (like PV) will not cause safety risks to engineers working on the network, and that the electricity fed into the network complies with mains power quality requirements. It is important to appreciate that these permissions are required for all grid-connected generators. This includes 'plug-and play' AC-modules.

Reputable PV system installers will normally ensure that all the required approvals are in place for you so that you can have full confidence in your new system.