FAQ’s

Most homeowners install a system of between 2-3kWp. The cost of installation will vary according to:

• how easy or difficult it is to access the roof
• the technology or product you choose

Typically, the installation will cost between £4,500-£6,000 per kWp.

There is no simple answer to this question. It will depend on:

• how much you want to invest
• how much of your electricity you want to generate via PV
• how much south-facing, un-shaded roof space you have

Most people install a system between 2-3KWp, generating between 1,700-2,500 kWh per annum. This is not the equivalent to total needs of a typical house which the EST estimates to be 3,300kWh. It is not essential to provide ALL of your homes electricity via solar PV (since you will still be connected to the national grid), even half will make a serious reduction to your carbon footprint. In terms of space, you will need approximately seven square meters per kWp.

Yes. On top of the generation tariff you will receive for every unit you generate, the Government’s consultation paper proposes that you are paid 5p per kWh for every unit exported.

Solar photovoltaic systems are silent in operation, have no moving parts and require little maintenance. During the lifetime of the system, you may well need to replace the inverter at a cost of approximately £500-600.

Yes. The cells in the tiles only require daylight to work, and will even generate energy on cloudy days. The UK has similar irradiance levels to Germany where PV has proved extremely popular given the tariff environment which we will have in the UK from next April.

We estimate pay back in eleven years. In simple terms, if you were to spend £10,000 on a system today, you would receive over 9% of your investment back per annum guaranteed for 25 years.

Daylight hits the photovoltaic cells and is converted to clean electricity. The inverter converts the electricity from direct to alternating current, for use in the home. When the solar energy system is producing more power than is needed it is exported to the grid. At night, power is imported from the grid in the normal way.

No, the systems Datalex install are connected to the national grid. In the night, when the panels are not generating energy, electricity is bought from the utility company in the normal way. Any excess electricity generated during the day, for example when you are at work, is sold back to the utility company.

This depends on how much PV you have installed or how big your system is.

Our photovoltaic systems for homes are entirely grid connected. If there is a power cut your system is automatically switched off. This is a safety measure designed to stop electricity leaking on to the national grid and to protect individuals who may be working to restore the power supply.

The 'efficiency' of solar panels is less relevant than you might imagine, the sun contains an incredible amount of energy! More important is the kWh/kWp (kilo watt hours (or 'units') per kilo watt peak) you will generate. The government quote this as 850kWhs/kWp for the UK, but we have seen 1000kWhs/kWp for some system in the UK.

So if you had a 4kWp system (about 30m2) you could generate 4x850=3400 units a year (at the gov figures), which is more than you need in a 3 bed house with all mod cons AS LONG as you are 'energy aware' and not frivolous with your usage!

Orientation, shading and the temperature of the PV elements all impact on their output and must be considered at the design stage. The best orientation for solar PV in the UK is south facing at 30 - 40°.

Of course, the more energy efficient the building, the greater the overall benefit of the PV cells.

Some PV products have now been designed to provide thermal insulation as well as electricity - eg flat roof systems and solar metal roofing systems that include insulation and solar glass laminates with low emissivity glass.

The degree of soiling will depend on the location but usually dust accumulation and self-cleaning reach a steady state after a few weeks if the array tilt is at least 15 degrees. In extreme cases dust may cause a power reduction of about 10%. At low tilts horizontal glazing bars can trap debris which could lead to shading of part of the array. The design of the system should aim to minimise uneven soiling.

Solar modules have a manufacturer’s warranty of 25 years and a working lifetime of 40 years and beyond. Modules of all types usually have a twenty five year warranty, as do most thin-film integrated products. PV glass laminates usually have a ten year warranty. These times are only a rough guide and should be checked for each specific product.