Solar Photovoltaic PV
Solar photovoltaic (PV) uses energy from the sun to create electricity to run appliances and lighting. PV requires only daylight - not direct sunlight - to generate electricity.
How it works
Photovoltaic systems use cells to convert solar radiation into electricity. The PV cell consists of one or two layers of a semi conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers, causing electricity to flow.
The greater the intensity of the light, the greater the flow of electricity...
PV systems generate no greenhouse gases, a typical domestic system can save approximately 1.2 tonnes of carbon dioxide emissions per year - adding up to almost 30 tonnes over a system's lifetime.
PV arrays now come in a variety of shapes and colours, ranging from grey 'solar tiles' that look like roof tiles, to panels and transparent cells that you can use on conservatories and glass to provide shading as well as generating electricity. As well as enabling you to generate free electricity they can provide an interesting alternative to conventional roof tiles!
Solar PV and your home
You can use PV systems for a building with a roof or wall that faces within 90 degrees of south, as long as no other buildings or large trees overshadow it. If the roof surface is in shadow for parts of the day, the output of the system decreases.
Solar PV panels are not light and the roof must be strong enough to take their weight, especially if the panel is placed on top of existing tiles.
Stand-alone or grid-connected system?
Small-scale solar PV is particularly suitable for remote off-grid locations where conventional methods of supply are expensive or impractical. Most small solar PV systems generate direct current (DC) electricity. Off-grid systems require battery storage and an inverter to convert DC electricity to AC (alternating current - mains electricity).
You also need a controller to divert power to another useful source (e.g. space and/or water heaters) when the battery is fully charged.
Solar PV systems can also be installed where there is a grid connection, your normal domestic dwelling. A special inverter and controller converts DC electricity to AC at a quality and standard acceptable to the grid. No battery storage is required. Any unused or excess electricity can be exported to the grid and sold to the local electricity supply company.
Cost and maintenance
Prices for PV systems vary, depending on the size of the system to be installed, type of PV cell used and the nature of the actual building on which the PV is mounted. The size of the system is dictated by the amount of electricity required.
For the average domestic system, costs can be around £5,000- £7,500 per kWp installed, with most domestic systems usually between 1.5 and 3 kWp. Solar tiles cost more than conventional panels, and panels that are integrated into a roof are more expensive than those that sit on top. Contact us to discuss your solar PV needs
A 2.5kWp array can provide enough electricity to meet around half a households electricity needs, this equates to a big savings a year.
Grid connected systems require very little maintenance, generally limited to ensuring that the panels are kept relatively clean and that shade from trees has not become a problem.
Stand-alone systems, i.e. those not connected to the grid, need maintenance on other system components, such as batteries.
