While it is possible to build your own alternator from powerful Neodymium Magnets and coils of enamelled wire an amateur should consider purchasing a ready made and tried and tested Permanent Magnet Generator* for their Wind Turbine.
Wind turbine blades (for example, home made DIY PVC or carved wooden blades), a waterwheel (connected through a gear box), or even a bicycle can then be attached to spin the generator and produce AC electricity.
* note that a ‘generator’ outputs DC voltage, whereas an ‘alternator’ outputs AC voltage. The vast majority of ‘generators’ sold for use in renewable energy systems are in reality alternators. True DC outputting generators are available – typically treadmill motors and similar which can be re-purposed.
The generated AC electricity must then be passed through a suitable Bridge Rectifier to produce DC electricity which can be stored in batteries and/or passed through a power inverter for domestic use. Click here for details of where you can purchase three phase bridge rectifiers of the type pictured above.
Pictured above is such a Permanent Magnet Generator (used by Dick Strawbridge in BBC2’s It’s Not Easy Being Green on his Waterwheel) available in 12, 24, 36, and 48 Volt configurations. Gearing wastes energy and generates nuisance noise, so PM-Generators for wind (and waterwheel etc) applications are designed to produce high power outputs at low RPM.
This Futurenergy model weighs in at just 7kg and the main body is just 18 x 7cm. The 12V model generates 662 Watts at 380 RPM, and 53 Watts at just 260 RPM. The 48 Volt model generates just 42 Watts at 380 RPM, but 1472 Watts at 610 RPM.
Higher voltage generators are more suited to locations with high average wind speeds and strong gusts, and the lower voltage generators more suited to locations with lower wind speeds on average and limited gusts.
At the time of updating this article (October 2013) these are all available for just under £300.
Buy a Permanent Magnet Generator
Permanent magnet generators and alternators are not the easiest things to find from retailers – the best place to go is usually eBay from where the selection pictured below were found. Prices start from around £150 with power ratings and voltages suitable for most projects.
Click here to search eBay now for Permanent Magnet Generator, or here for Permanent Magnet Alternator. (Far fewer results are usually returned when searching for alternator rather than generator but it is worth doing both searches to find everything that is available.)