Microgeneration vs renewable definitions UK
If you are looking into solar panels, heat pumps or a small wind turbine, you will quickly come across the terms “microgeneration” and “renewable energy”. They are often used as if they mean the same thing, but in UK law and for grant eligibility they are distinct categories. Understanding the difference can affect which technologies you can install, what certification you need and what financial support you can claim.
Microgeneration is defined by equipment size (up to 50 kW electrical or 45 kW thermal), while renewable energy is defined by source with no capacity limit. A gas-fired micro-CHP boiler is microgeneration but not renewable, and a 100 kW wind turbine is renewable but not microgeneration. Check the definitions to see which category your technology falls under.
- Microgeneration is capped at 50 kW electrical or 45 kW thermal capacity.
- Renewable energy has no size limit, defined by source only.
- A gas-fired micro-CHP boiler is microgeneration but not renewable.
- A 100 kW wind turbine is renewable but not microgeneration.
- Check MCS certification for grant eligibility under microgeneration rules.
- Microgeneration vs renewable definitions UK
- Microgeneration means small-scale generation and is defined by capacity limits, not fuel type
- A renewable energy source must come from naturally replenished resources, with no capacity cap
- The MCS certification scheme only applies to microgeneration technologies, not all renewables
- Quick numbers — how capacity and fuel type separate microgen from renewable
- For the Smart Export Guarantee, the key requirement is microgeneration, not renewable
- The Renewable Heat Incentive (RHI) closed, but its replacement scheme uses the renewable definition
- Verifying an installer — check MCS for microgen, but also check Gas Safe or NICEIC for the fuel type
Microgeneration is defined by the size of the equipment (up to 50 kW electrical or 45 kW thermal), regardless of what fuel it uses. Renewable energy is defined by the source (sun, wind, water, geothermal or biomass), with no size limit. A gas-fired micro-CHP boiler is microgeneration but not renewable, while a 100 kW wind turbine is renewable but not microgeneration.
Microgeneration means small-scale generation and is defined by capacity limits, not fuel type
The UK government defines microgeneration in the Climate Change and Sustainable Energy Act 2006 as technologies that produce heat or electricity with a capacity of 45 kW thermal or 50 kW electrical or less (legislation.gov.uk, 2006). This definition covers any small unit — solar PV, a wind turbine, a heat pump, or a micro-CHP boiler — regardless of whether the energy source is renewable.
The key distinction for homeowners is that a gas-fired micro-CHP boiler qualifies as microgeneration but is not renewable because it burns fossil fuel. The capacity cap is the sole criterion for microgeneration status. If a wind turbine is rated at 60 kW, it exceeds the 50 kW electrical limit and therefore is not classed as microgeneration, even though it is clearly renewable.
A renewable energy source must come from naturally replenished resources, with no capacity cap
The UK government defines renewable energy in the Energy Act 2004 and subsequent legislation as energy from sources that are naturally replenished — sunlight, wind, water, geothermal heat, and biomass (legislation.gov.uk, 2004). Unlike microgeneration, there is no upper capacity limit for a technology to be classed as renewable; a 500 MW wind farm is renewable, a 1 kW gas generator is not.
For homeowners, the practical difference is straightforward. Solar panels, heat pumps, and wind turbines are both microgeneration and renewable. A gas boiler (even a micro-CHP unit) is only microgeneration. The Department for Energy Security and Net Zero (DESNZ) confirms this in the UK Renewable Energy Roadmap, which treats large-scale wind and solar as renewable regardless of size (GOV.UK, 2026).
The MCS certification scheme only applies to microgeneration technologies, not all renewables
The Microgeneration Certification Scheme (MCS) certifies installers and products for small-scale generation up to 50 kW electrical or 45 kW thermal, aligning directly with the microgeneration definition (MCS, 2026). Large-scale renewable installations (for example, a community wind farm rated at 200 kW) do not require MCS certification; they fall under other standards like NICEIC or NAPIT for electrical work.
For homeowners seeking grants or export tariffs (such as the Smart Export Guarantee), the installation must typically be MCS-certified — even if the technology is renewable. This means a solar PV system under 50 kW needs MCS certification to qualify for payments, while a larger commercial solar array does not. The MCS website provides a searchable database of certified installers.
Quick numbers — how capacity and fuel type separate microgen from renewable
| Feature | Microgeneration | Renewable Energy |
|---|---|---|
| Capacity limit | ≤50 kW electrical / ≤45 kW thermal | No upper limit |
| Fuel source | Any (gas, oil, solar, wind) | Naturally replenished only |
| Example: Solar PV | Yes (if ≤50 kW) | Yes |
| Example: Gas micro-CHP | Yes (if ≤50 kW) | No |
| Example: 100 kW wind turbine | No (exceeds capacity) | Yes |
| MCS certification required for grants | Yes | Only if also microgen |
For the Smart Export Guarantee, the key requirement is microgeneration, not renewable
The Smart Export Guarantee (SEG) requires the generating technology to be microgeneration (≤50 kW) and MCS-certified, but does not require the source to be renewable (Ofgem, 2026). In practice, nearly all SEG-eligible installations (solar PV, wind, hydro) are renewable, but a micro-CHP running on natural gas would also qualify if MCS-certified.
The rate paid is set by the energy supplier, not fixed by government. Typical rates in 2026 range from 4p to 15p per kWh exported, depending on the supplier and technology. Ofgem publishes a full list of SEG licensees and their current tariff rates. Homeowners should compare offers because rates vary significantly and are not guaranteed for the long term.
The Renewable Heat Incentive (RHI) closed, but its replacement scheme uses the renewable definition
The Domestic Renewable Heat Incentive closed to new applicants in March 2022. The Boiler Upgrade Scheme (BUS) replaced it from 2022 onward. The BUS only supports renewable heating technologies — heat pumps (air source, ground source) and biomass boilers — and explicitly excludes fossil-fuel microgeneration like gas micro-CHP (GOV.UK, 2026).
As of 2026, the BUS offers a grant of £7,500 for an air source heat pump and £7,500 for a ground source heat pump (Ofgem, 2026). The grant is deducted from the installation cost by the installer, not paid to the homeowner directly. Eligibility requires the property to have a valid Energy Performance Certificate (EPC) with no outstanding recommendations for loft or cavity wall insulation.
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Verifying an installer — check MCS for microgen, but also check Gas Safe or NICEIC for the fuel type
For any microgeneration installation (renewable or not), homeowners should verify the installer holds MCS certification for that specific technology. The MCS website provides a searchable directory of certified installers (MCS, 2026). For gas-related microgeneration (such as micro-CHP), the installer must also be Gas Safe registered (Gas Safe Register, 2026).
For electrical microgeneration (solar PV, wind), the installer should be registered with NICEIC or NAPIT for Part P compliance under building regulations (NICEIC, 2026). Checking these registrations before work begins protects you against poor installation and ensures you can access grants and export tariffs that require certified work.
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Frequently Asked Questions
Microgeneration is defined by equipment size (up to 50 kW electrical or 45 kW thermal), regardless of fuel source. Renewable energy is defined by the source (sun, wind, water, etc.) with no capacity limit. The Climate Change and Sustainable Energy Act 2006 sets the microgeneration definition, while the Energy Act 2004 defines renewable energy.
Yes, a gas-fired micro-CHP boiler qualifies as microgeneration if its capacity is 50 kW electrical or 45 kW thermal or less. However, it is not renewable because it burns fossil fuel. Ofgem confirms this distinction for grant eligibility.
No, a 100 kW wind turbine exceeds the 50 kW electrical limit for microgeneration, so it is not classed as microgeneration. It is still renewable energy because it uses wind. The MCS certification scheme applies only to microgeneration-sized systems.
Microgeneration is defined as any technology with a capacity of 50 kW electrical or 45 kW thermal or less, as set out in the Climate Change and Sustainable Energy Act 2006. This applies to heat pumps, solar PV, wind turbines, and micro-CHP units.
No, renewable energy has no capacity limit under UK law. The Energy Act 2004 defines it by source (sun, wind, water, geothermal, biomass) alone. A large solar farm or offshore wind farm is renewable but not microgeneration.
