A straightforward and proven means of harvesting the sun's energy to provide free hot water, roof mounted solar thermal panels contain small pipes through which water is pumped and heated by the sun's rays.
A typical system consists of 3-4 sqm of panels mounted on a south-facing roof, feeding into a 200-litre tank. This will provide around 50% of an average households hot water needs (higher in the summer months).
The system can be mounted on any roof as long as it can bear the load and is compatible with most boiler systems, except combination boilers.
Costing between £2,500-£4,000, investing in solar thermal panels will pay for itself in less than 20 years.
Contact the Solar Trade Association (01908 442290: greeenergy.org.uk/sta) for further information and an accredited list of suppliers and forthcoming green events.