The bigger the array the more you generate and the bigger your income.

There are six main factors that will affect the output from a solar PV system:

Total size of the PV array

Each kWp requires approximately 8m² of area. A certain area should ideally be left around the perimeter of the array to minimize wind loading and extra turbulence. We aim to leave a border of approximately 0.2m.

Type of module used

Amorphous
These modules are not too susceptible to shading and are suited to low light levels. We use Unisolar modules. There are even flexible modules of this type available which can be attached to a metal seamed roof.

Polycrystalline
These modules are made from multiple silicon crystals and are extremely good value for money.

Monocrystalline
These modules are made from pure silicon crystals and have a higher efficiency than Polycrystalline cells.

Hybrid
Hybrid modules combine monocrystalline technology along with amorphous. These are top of the range with higher efficiencies. However they are also the most expensive option. Where roof space is limited these are the preferred option as they maximise output from a limited area. Typically a module like the Sanyo HIT (one of our favourites) will produce 10% more power over a year than a monocrystaline module.

The orientation from due south

The array should ideally face due south,

but SW or SE will produce almost as much output on an averagely pitched roof.

The latitude of the installation

Basically, the further south you are, the better. As you've probably guessed, the South Coast is one of the best placed areas in the UK to install solar panels.

The estimates we use to calculate returns are based on the Governments SAP calculation. this uses sunlight from data logged in Sheffield. You can see from the diagram above that sunlight levels in the south are significantly better than those in the north, so your aray should perform significantly better than the figures we quote!. Our demonstration system base in Corfe Mullen is currently producing 20% more than originally estimated.

The angle from horizontal

The ideal angle from horizontal is between 30-45 degrees. Other angles are also suitable but slightly less efficient.

Anything which shades the panels

Shading of the panels can dramatically reduce the electrical output  Shading should therefore always be avoided, especially from any trees or buildings to the south of the array.