Wind Power

Wind power  is probably the cheapest renewable technology to install at home. If you have good wind conditions and an unobstructed path for the wind in all directions, then it could be worth thinking about. You really need the wind generator mounted up as high as you can get it and clear of any obstructions like buildings or trees in order to avoid turbulence. If you live at a high location or near to the sea, then wind power could well be very effective. Wind turbines are, of course, mechanical devices with moving parts, so will almost certainly require regular maintenance. This must be factored in as a recurring cost when working out the viability of a system. 

Before you invest in a wind turbine, it is very sensible to have some idea of the wind speed at your chosen location. This can be researched from the National Wind Speed Database, but very useful local measurements can be made using an Anemometer. This can be a simple hand held device, or quite sophisticated instruments are available which record wind speed data over a long period. You can experiment with different locations to see which yield the best results.

There are various models and power ratings of wind turbines available and the best thing to do is to analyse your power requirements and invest in a turbine big enough to achieve this. Wind Turbines are rated according to their output in Watts at a given wind speed. Be very careful when choosing a turbine as the specified wind speed may be a lot higher than the average speed at your location. The big advantage of wind power is that it can be available day and night, but there will always be periods of calm when nothing is produced. Turbines can be heavy and noisy and this should be borne in mind when deciding on the site for your installation.

You need to decide what you are going to do with the electricity your turbine produces. Most people, when they first start with renewable energy, will decide to store the electricity produced in batteries, for later use. There are various types of batteries available and you should first work out how much power you want to store and for how long. If you just want power for some low power room lighting, then a single small battery will probably be sufficient. If, however, you need a week's supply for the whole house, then you would need a very large bank of batteries and this will be expensive. You get what you pay for with batteries and it is always best to buy a genuine Deep Cycle type of battery, as a normal car battery is not designed for the constant charge and discharge cycling that a wind turbine system requires.

With a battery storage system you will also need a Wind Turbine Charge Controller. This is a device that limits the charge to a battery system to prevent overcharging and is essential to keep your batteries in top condition. Some regulators even have a monitoring and logging system which will show you exactly how much power has been harvested and what charge level the batteries are at. Try to get one that has metering for voltage and current, so that you can be kept informed of your system's performance.

If you want more than just a low voltage system, then you are going to need an inverter to step up the battery voltage to mains voltage and frequency, 230 volts AC, 50 Hz. There are two different types of inverter available. The cheapest type only produce power whose waveform is not a pure sine wave like the mains is. This will be fine for most non-critical lighting applications etc. but televisions and computers may not be happy with them. These inverters are sometimes called Quasi- Sinewave inverters.

The best type of inverter is the type that exactly replicates the mains supply. This type is called the Pure Sine Wave invertor and is a little more expensive, but can be used to provide power for any type of mains equipment. Whichever type you decide on, be sure to choose one that will handle the power you need. Often, loads with electric motors, need a very high current to start them moving, so always buy an inverter large enough to handle this inrush current.

There is another type of inverter which enables you to dispense with the battery and charge controller, as all power produced is fed back into the mains wiring of your house and then, if it is not used by you, it is exported to the grid. This is called a Grid-Tie Inverter and is becoming a very popular choice for renewable energy enthusiasts. Effectively, you use the electricity grid as a large battery and when you are not using your own power, it is exported for others to use. You can be paid for this exported power and most electricity suppliers have a buy back micro-generation tariff. People who have large wind turbines installed at their homes almost always have this type of system, as it is very reliable and can be a selling point for the house.