FAQ - Pre-Sales & Installation

What does "PV" stand for and how do PV panels work?

PV is an abbreviation for Photovoltaic. PV panels comprise of many cells that are made from one or two layers of semiconducting material, usually silicon. When light shines on the cell it excites the silicon cells and creates an electric field across the layers. The stronger the sunshine, the more electricity that is produced. The strength of a PV cell is measured in kilowatt peak (kWp). That's the amount of energy the cell generates when performing at its maximum capacity.

What is the difference between solar hot water and Solar PV?

Solar hot water systems use the heat of the sun to warm a liquid that flows through solar collectors (usually situated on the roof) which in turn heats water in a storage cylinder producing hot water at the taps or for a shower. Solar PV systems use solar cells to convert the energy from the sun into electricity to power electrical appliances within a building or to be exported to the national grid.

Is my roof suitable for a PV system?

PV systems should be installed on a roof or wall that faces within 90 degrees of south, and isn't overshadowed by trees or buildings in order to work efficiently. If the surface is in shadow for parts of the day, the system will generate less energy.

Where can I install a PV system?

Maximum output comes from south facing roofs that are between 30-40 degrees from horizontal. A PV system should not be installed in shade as this will decrease the output from the system. Although most systems are installed on a roof, they can be installed on any surface such as facades, sunshades, garages or ground mounted. They are normally installed in locations that receive sunshine through most of the day.

What are the effects of shade on a Solar PV system?

Shading is critical and even minor shading can result in a significant loss of energy being produced by the solar array, so it is best to avoid shading wherever possible, especially from any trees or buildings to the south of the array. This is because the cell with the lowest illumination determines the operating current of the series string in which it is connected and shading to even just one cell can reduce the power output to 50% of its full available value.

Do I need planning permission for a PV system?

In most cases, planning permission is not required. However, some authorities do require planning permission especially for listed buildings or within a conservation area. Your local authority will be able to provide you with information on your home's eligibility and we will be happy to guide you through this process if needs be.

What is the life span of a PV system?

The warranty conditions for PV panels typically guarantee that panels can still produce at least 80% of their initial rated peak output after 25 years. So manufactures expect that their panels last at least 25 years, and that the efficiency decreases by less than 1% per year.

Do I need direct sunshine for my PV system to work?

A PV system does not need direct sunlight for it to work, even on cloudy days it will still produce electricity.

Does the price include the required Scaffolding?

We include scaffolding required for a the PV installation in all our prices, many other PV installers do not include the cost of the necessary scaffolding at your property when providing a quotation.

Will a solar PV system cut my carbon footprint?

Solar electricity is a green renewable energy and doesn't release any harmful carbon dioxide (CO2) or other pollutants. A typical home PV system could save over 1 tonne of CO2 per year - that's more than 30 tonnes over its lifetime.

Will a solar PV system save me money on my electricity bill?

Yes, you will be paid a fixed rate via the Feed In Tariff for every kWh of electricity you generate, whether you use it yourself or not. You are free to use the electricity you generate, which will then reduce your energy bills as you will not need to purchase as many units of electricity from your normal supplier. In addition, you will be paid a minimum of 3p/kWh for any electricity you generate that you export to the national grid. In most cases an export meter is not fitted and the export rate is deemed at 50% of the total generation created by the PV system. As the Feed In Tariff is paid regardless of whether the electricity generated by the system is used or not and the rate of export is deemed, in the majority of cases, you are best using as much of the electricity generated as possible in order to minimise the number of units of electricity you purchase from your energy supplier and thus saving you money on your electricity bill.

What if I produce more electricity through my Solar PV system than I need?

Whenever your panels are producing more electricity than your home is using, it will exported back to the National Grid. As long as you have an arrangement with your energy company, you will be paid for this electricity so you can be sure that your energy bills will be lower and none of your clean, green electricity will be wasted. Please note that under the new Feed In Tariff all exported electricity will be paid at an agreed set rate irrespective of the energy supplier who purchases that electricity. This is in addition to the tariff for the total amount generated by the solar electricity system.

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Watt-NRG did a great job on our installation; they were prompt, tidy and efficient. After a year, the installation is out-performing the generation promises with no problems. Very pleased.