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Heat your home and generate electricity with a micro-CHP unit

Micro combined heat and power (micro-CHP) is a technology that generates heat and electricity simultaneously, from the same energy source, in individual homes or buildings. The main output of a micro-CHP system is heat, with some electricity generation, at a typical ratio of about 6:1 for domestic appliances.

A typical domestic system will generate up to 1kW of electricity once warmed up: the amount of electricity generated over a year depends on how long the system is able to run. 

How does micro-CHP work? 

Domestic micro-CHP systems are powered by mains gas or LPG; in the future there may be models powered by oil or bio-liquids. Although gas and LPG are fossil fuels rather than renewable energy sources, the technology is considered a ‘low carbon technology’ because it can be more efficient than just burning a fossil fuel for heat and getting electricity from the national grid.

Micro-CHP systems are a similar size and shape to standard domestic boilers, and can be wall hung or floor standing.

The difference to a standard boiler is that they are able to generate electricity while they are heating water.

There are three main micro-CHP technologies (the difference is the way in which they generate electricity)

1. Internal combustion engine CHP

This is the most proven technology. These are essentially, and sometimes literally, truck diesel engines modified to run on natural gas or heating oil, connected directly to an electrical generator. Heat is then taken from the engine’s cooling water and exhaust manifold. The engines can have a higher electrical efficiency than a Stirling engine but are larger and mainly installed in commercial-scale applications.

2. Fuel cell CHP technology

Fuel cells work by taking energy from fuel at a chemical level rather than burning it. Although the technology is still not widely available to consumers, there are some units that are commercially available in the UK. We recommend to check the MCS product list for certified products.

  • Electricity generation as a by-product of heat. When the micro-CHP is generating heat, the unit will also generate electricity to be used in your home (or exported).
  • Carbon savings. By generating electricity on-site, you could be saving carbon dioxide compared with using grid electricity and a standard heating boiler.
  • Installation is easy. For the householder, there is very little difference between a micro-CHP installation and a standard boiler. If you already have a conventional boiler then a micro-CHP unit should be able to replace it as it’s roughly the same size. However, the installer should be approved under the Microgeneration Certification Scheme
  • Servicing costs and maintenance should be similar to a standard boiler – although a specialist will be required. 
  • Micro-CHP was eligible for Feed-In Tariff payments. The FITs scheme closed to new applications on 31 March 2019. If you have already installed a system with a MCS certificate dated on or before 31 March 2019 you may still be able to apply. For more information about the FITs scheme and recent changes please visit our Feed-In Tariffs page

Costs, savings and financial support

A micro-CHP system will cost more than the traditional boiler without the technology.

The micro-CHP boiler will need to be on in order for it to generate any electricity. The electricity is can generate won’t cover all of the average household’s electricity demand, but will help to cover some, reducing the amount of electricity required from the grid.

  • For any electricity you don’t use in the home, the Smart Export Guarantee guarantees payment for exported electricity for qualifying systems. Please visit our Smart Export Guarantee page for more information.
  • Micro-CHP was eligible for Feed-In Tariff payments. The Feed-In Tariffs scheme closed to new applications on 31 March 2019. If you have already installed a system with a MCS-certificate dated on or before 31 March 2019, you may still be able to apply. For more information about the Feed-In Tariff scheme and recent changes please visit our Feed-In Tariffs page.

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