Generate power

Renewable energy technologies like solar panels, wind turbines, and biomass heaters are becoming increasingly popular.

These are effective alternatives to fossil fuels and will help you to meet your own energy requirements and reduce your home's carbon dioxide emissions.

Small scale wind

Wind turbines use the wind's lift forces to rotate aerodynamic blades that turn a rotor which creates electricity.

But it's still largely untapped and only 0.5% of our electricity requirements are currently generated by wind power.

How does it work?

Most small wind turbines generate direct current (DC) electricity. Systems that are not connected to the national grid require battery storage and an inverter to convert DC electricity to AC (alternating current - mains electricity)..

Wind systems can also be connected to the national electricity grid. 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 may be able to be exported to the grid and sold to the local electricity supply company.

There are two types of wind turbines:

• Mast mounted - which are free standing and located near the building(s) that will be using the electricity.

• Roof mounted - which can be installed on house roofs and other buildings

Benefits

Wind power is a clean, renewable source of energy which produces no carbon dioxide emissions or waste products.

Is it suitable for my home?

Individual turbines vary in size and power output from a few hundred watts to two or three megawatts (as a guide, a typical domestic system would be 1 - 6 kilowatts). Uses range from very small turbines supplying energy for battery charging systems (e.g. on boats or in homes), to turbines on wind farms supplying electricity to the grid.

You should consider the following issues if you're thinking about small scale wind. An accredited installer will be able to provide more detailed advice.

• Wind speed increases with height so it's best to have the turbine high on a mast or tower.

• Generally speaking the ideal site is a smooth top hill with a flat, clear exposure, free from excessive turbulence and obstructions such as large trees, houses or other buildings.

• Small scale wind power is particularly suitable for remote off grid locations where conventional methods of supply are expensive or impractical.

Please note that the electricity generated at any one time by a wind turbine is highly dependent on the speed and direction of the wind.

The windspeed itself is dependent on a number of factors, such as location within the UK, height of the turbine above ground level and nearby obstructions. Ideally, you should undertake a professional assessment of the local windspeed for a full year at the exact location where you plan to install a turbine before proceeding. In practice, this may be difficult, expensive and time consuming to undertake.

Therefore we recommend that, if you are considering a domestic building mounted installation and electricity generation is your main motivation, then you only consider a wind turbine under the following circumstances:

• The local annual average windspeed is 6 m/s or more.

• There are no significant nearby obstacles such as buildings, trees or hills that are likely to reduce the windspeed or increase turbulence

Solar electricity

Solar PV (photovoltaic) uses energy from the sun to create electricity to run appliances and lighting.

PV requires only daylight, not direct sunlight to generate electricity and so can still generate some power on a cloudy day.

How does it work?

Photovoltaic systems use cells to convert sunlight 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 cells are referred to in terms of the amount of energy they generate in full sunlight, know as kilowatt peak or kWp.

The benefits

PV systems produce no greenhouse gases and each kWp can save approximately 455kg of carbon dioxide emissions per year, adding up to about 11 tonnes over a system's lifetime.

Is it suitable for my 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.

Other sources of small scale generation are:

• Ground source heat pumps

• Small scale hydro

• Solar water heating

• Biomass