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Hydro technology uses running water to generate electricity

Whether it's from a small stream or a larger river, small or micro hydroelectricity systems, also called hydropower systems or just hydro systems, can produce enough electricity for lighting and electrical appliances in an average home.

How do hydropower systems work? 

All streams and rivers flow downhill. Before the water flows down the hill, it has potential energy because of its height.

Hydro power systems convert this potential energy into kinetic energy in a turbine, which drives a generator to produce electricity. The greater the height and the more water there is flowing through the turbine, the more electricity can be generated.

The amount of electricity a system actually generates also depends on how efficiently it converts the power of the moving water into electrical power.

Find out more about different kinds of technology at the British Hydro Association.

See the Guide to Hydropower Construction Best Practice for information for scheme owners and those working on hydro construction sites in Scotland.

The benefits of hydro systems 

A hydro system can generate 24 hours a day, often generating all the electricity you need and more. 

  • Cheap heating and hot water 

A hydro system may generate more electricity than you need for lighting your home and powering your electrical appliances – so you can use the excess to heat your home and your hot water too.

  • A cheaper option for off-grid homes

Installing a hydro system can be expensive, but in many cases it's less than the cost of getting a connection to the National Grid if you don’t already have one. Find out more about off-grid options.

  • Cut your carbon footprint

Hydroelectricity is green, renewable energy and doesn't release any harmful carbon dioxide or other pollutants.


If you live in Scotland, find case studies and examples of homeowners who have installed a micro hydro system using our Green Homes Network tool.
Will hydropower work for me? 

Hydropower is very site specific. Most homes will not have access to a suitable resource even if they have a water course running nearby. Assessing a hydro site properly is a job for a professional. If you think you might have a suitable site the next step is to contact a certificated installer, who can assess your site.

To be suitable for electricity generation, a river needs to have a combination of

  • flow – how much water is flowing down the river per second, and 
  • head – a difference in height over a reasonably short distance.

It’s also important to consider what happens to the river in summer. The minimum flow during dry periods is usually the deciding factor, no matter how impressive the river looks when it is in flood.

If there is a good hydro resource in or near your community it might be worth developing it as a community energy project, rather than as a system to supply just one home. 

Find out more about hydro power systems and the planning permissions and licenses required.


Is your home connected to the National Grid? If not, hydro schemes are one of the most reliable alternatives to mains supply for isolated properties, and can sometimes be cheaper to install than a new mains connection.

Costs, savings and financial support 

Costs for installing a hydro system can vary, depending on the location and the amount of electricity you can generate.

Some sites cost less than this to develop; others cost much more due to the nature of the site and the equipment used.

Maintenance costs vary but are usually low as hydro systems are very reliable.

Savings will depend on the number of hours the turbine is able to run in a year, which in turn will depend on how often the level of the river is high enough to supply the system. Your installer will be able to predict this for you and estimate the amount of electricity that will be generated.

Hydro was eligible for Feed-in Tariffs, which earned a tariff for each kWh of electricity generated by your system if it was registered before 31st March 2019. 

The UK Government proposes to introduce a Smart Export Guarantee (SEG) in the near future. The SEG will mean that large electricity suppliers are required to pay small-scale generators a price per kWh for the electricity they export to the grid. Smaller suppliers will also be able to opt into the SEG but they will then have to adhere to the rules and guidance. 

Unlike with FITs, electricity suppliers would determine the tariff they are willing to pay to small-scale generators. It is thought that this will result in competition between suppliers. 

It would also be up to suppliers to determine the length of contracts with customers and it is the intention that the SEG scheme would only be in place until a time when the market can operate without government intervention. 

You can find out more about the proposals for the SEG, on the UK Government website


Making the most of hydroelectricity

To make the electricity you produce go further:

By not using all the electricity you generate, you can: 

  • Sell the surplus back to the grid, if you're connected, to earn extra money
  • Store some of the surplus in batteries to use later if you're off grid.


Once installed, most systems can last for 40-50 years, with low running and maintenance costs and could last for longer if well maintained.

There is potential for damage by debris carried downstream at times of flood, but screening the intake should minimise this risk.

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