Hydro installations are extremely site specific. Prices vary widely depending on the type and size of system, access to the site, and how much work you are willing to put in yourself.
The basic equipment for a 1kW off-grid battery charging system might cost £5,000 to £6,000 plus installation costs. If you have the technical skills it may be possible to put in a small DIY scheme for under £10,000. In some situations this will be cheaper than paying grid-connection costs.
The total cost of a Pelton turbine producing 5kW on a 25m head site might be around £25,000 if professionally installed, less on a DIY basis. Larger systems can cost tens of thousands of pounds. There is an economy of scale - a 5kW system may only cost 50% more than a 2kW system.
Because of the investment required, it makes sense to minimise energy use first; efficiency measures are a more costeffective way to reduce domestic carbon emissions. See our Energy Conservation section for advice.