Solar panels FAQ

What are Photovoltaic solar panels?

Put simply, Photovoltaic panels (or PV panels as they are widely known), are electrical devices that convert light into DC electricity. The light is harvested from the sun and as long as it is the right colour (white light is all colours) some electricity will be produced from a solar cell. The more intense the light, the more electricity is produced. Each cell produces only a small amount of power, but when the cells are strung together in series to make solar modules they become more useful. A solar module can then be installed with other modules to form an array. The total energy output can be quite substantial.

How do solar panels work?

A solar cell is a semiconductor diode that when stimulated with light, produces an electron and a positive charge on opposite sides of the cell. Wires collect the charge of each side of the cell and take this electricity to the load circuit, such as a light bulb. Wiring cells in series increases the voltage, and in parallel increases the current output. For the cells to be useful, they must be put together in a system with other components sometimes called a ‘photovoltaic system’ or a ‘solar energy system’ or a ‘solar electric system’ or a ‘solar PV system’.

Do I need planning permission for the solar panels?

From April 6th 2008, all homeowners will be able to install Microgeneration equipment, like solar panels, without needing to get planning permission, as long as there is clearly no impact on others.

Can I power my whole building from a solar panel system?

With an ‘off-grid’ system it would not be cost-effective to power air conditioning, heat pumps, immersion heaters, electric boilers, electric cookers and electric room heaters as they draw a massive amount of electricity and would cost a fortune to run. But, when a PV system is ‘Grid-Connected’, under normal operating conditions, generally all the house loads are met by a combination of the PV system and the utility grid in the daytime. Sometimes these loads can be totally met by the PV system in the daytime and met by the utility grid at night.

Will a solar energy system heat my hot water?

No. Using solar panels to generate heat is extremely inefficient and uneconomical. You should use a solar thermal system to heat hot water.

Will my solar power system have batteries?

Usually, only if the system is ‘Off-Grid’. Batteries will be essential for the storage of electricity so you can use electrical equipment when there is no sunlight. Grid-Connected PV systems don’t need batteries, however, you can have batteries with a grid-connected installation if you wish to have power during power cuts, you need to determine this before the installation.

Grid-Connected solar power systems usually don’t have batteries so are simpler to install and have less hardware that could potentially fail. Because they are less expensive this makes them more cost-effective. Whether you have a Grid-Connected PV system with or without batteries, excess electricity produced by the solar panels will be directed back to the national grid. You will receive money back for any power that you ‘sell’ to the utility company.

What happens during a power cut?

With a grid-connected solar panels system, the inverter will automatically disconnect itself from the utility grid when there is a power cut. This is to prevent back feeding the grid and putting engineers working to restore power in danger. But, if you have a grid-connected PV system with battery backup it will automatically switch to backup power with little detection. Both these systems will automatically hook back up to grid once power is restored.

How much energy can solar panels produce?

The amount of electricity that is generated by solar panels will be estimated by our solar photovoltaic software and varies from system to system.

Can I sell excess electricity?

With a grid-connected system, you will have an inverter that imports and exports electricity as you need them. When you export electricity you will get paid for it. However, for installations below 30kWp, an export of 50% from power generated is deemed and you`ll get paid for it at the current regardless of whether you are exporting or not.

Do solar panels work at night?

PV panels cells will generate more electricity on bright days than when skies are overcast. But PV’s do not need to be in direct sunlight to work, even on overcast days and at night, a PV cell will be generating some electricity.

How long do solar panels last?

The average lifetime of a PV panels module is in excess of 25 – 30 years, crystalline silicon modules, in particular, have a very long life span. In addition, they require very little maintenance. Other system components like the batteries for the off-grid system should last 10 – 15 years if you buy a good brand.

Sunpower solar panels price

As a guideline, for grid-connected PV you will be looking at around £1,800 – £3,000 per kWp installed.

How much will I need to power my home?

The size of your system will depend on your location and power requirements both in AC and DC. According to the Energy Saving Trust, the average 3 bedroom house consumes 3,300 units of electricity (kWh) a year excluding cooking and heating. To find out how much electricity you use to call your electricity supplier or check your bills. You can then compare your consumption to the output of the system we size for you. By doing this you’ll get a good idea of how much you will save.