MCS Heat Pump and Solar UK: MIS 3005, BUS and Planning

A heat pump and solar PV on one job in Great Britain bring three sets of rules: MCS standards, the Boiler Upgrade Scheme and planning limits. Each has its own size caps and dates. This page sorts them by what you need to do first, from certification to noise checks.

Last updated: November 2026.

This page covers Great Britain. It uses MCS documents, Ofgem, GOV.UK and the Planning Portal. We read them in October 2026. Rules differ between England, Wales and Scotland, so each section says where it applies.

Which standards apply to a heat pump plus solar job?

MCS describes itself as the UK’s quality mark for small-scale renewable energy technologies like solar panels, heat pumps and battery storage. Its standards also cover solar heating and biomass. The table lists the documents you meet on a combined job.

Sources: MIS 3005-D, MIS 3002 Issue 6.0 and MCS 020 a).

kWth means kilowatts of heat output. kWp means kilowatts of peak solar output.

The MIS 3005-D file covers design only. Installation rules for heat pumps are in other MCS documents. Find them in the MCS Standards and Tools Library.

For how to get certified, see our guide to MCS certification for UK solar installers. For the difference between MCS and non-MCS work, see MCS vs non-MCS.

Do commercial solar PV and heat pumps need MCS or DNO approval?

It depends on the size and on what you want to claim.

• Boiler Upgrade Scheme (BUS): GOV.UK says you can use the grant for your home or a building used for your business. The installer must be MCS certified. Air-to-air heat pumps are for homes only.
• Smart Export Guarantee (SEG): Ofgem’s generator guidance says solar PV up to 50 kW needs a certified installation and a certified installer. For PV above 50 kW and up to 5 MW, the installation must be certified but the installer need not be.
• Grid connection: MIS 3002 says the installer must notify the distribution network operator (DNO) under EREC G98 or G99. DNO means the company that runs the local power network. MIS 3002 says G99 applies when the total AC output of all generators, such as PV and a battery, is above 16 A per phase.
• Heat pumps: MIS 3005-D says the installation must be notified to the DNO, and permission sought to connect where needed.

Sources: GOV.UK, Apply for the Boiler Upgrade Scheme, Ofgem, SEG guidance for generators (Dec 2019), MIS 3002 clause 5.1.9, MIS 3005-D clause 3.1.7. For the G98 and G99 steps, see our G98 vs G99 guide.

MCS covers PV only up to 50 kWp and heat pumps only up to the sizes above. For larger commercial work, check the rules for your project with the DNO and your local authority.

What does the Boiler Upgrade Scheme pay?

Ofgem and GOV.UK list these grants. The grant is taken off the quote, so the customer pays less up front.

Sources: Ofgem, Boiler Upgrade Scheme and Ofgem, property owners. GOV.UK shows the same amounts, and says the extra £1,500 for oil or LPG homes with no mains gas runs until March 2027.

The grant covers the heat pump only. Solar panels are not a BUS technology. Ofgem also says there is 0% VAT on heat pump installation from 1 April 2022 to 31 March 2027.

Some web pages say BUS now runs to 2030, has a £400 million budget, or pays £2,500 for heat batteries. We did not find these on the Ofgem or GOV.UK pages we read, so this page does not repeat them.

Who can get a grant?

These rules come from Ofgem’s installer page.

• The property is in England or Wales.
• The new system replaces a fossil fuel or electric heating system.
• The owner has not had another public grant for the same costs, and the system is not funded by the Energy Company Obligation (ECO).
• Social housing and most new builds are not eligible. Self-builds can be.
• Air-to-water and ground source heat pumps need a seasonal coefficient of performance (SCOP) of at least 2.8. SCOP is the heat a pump makes for each unit of electricity over a year.
• Each heat pump must be 45 kWth or less, or 70 kWth for a cascade of pumps.
• Hybrid systems with a fossil fuel boiler are not eligible.
• If the property has a valid Energy Performance Certificate (EPC), the installer gives its number. If not, the installer gives other evidence.

Source: Ofgem, BUS installers.

How does the process work?

1. The installer agrees a quote that shows the grant as a deduction.
2. The installer applies for a voucher for the owner. Ofgem asks the owner to confirm consent.
3. After checks, Ofgem emails the voucher.
4. The installer has 3 months from the voucher date to finish (6 months for a ground source heat pump).
5. After commissioning and the MCS certificate, the installer asks Ofgem to redeem the voucher.
6. Ofgem checks the claim. It aims to pay on the next weekly payment day.

Sources: Ofgem, BUS installers and Ofgem, sign up and apply. From 3 November 2026, installers need a GOV.UK One Login to use the BUS installer area.

The Ofgem installer page says a new system must not be commissioned more than 120 days before the voucher application is properly made. The GOV.UK owner page says the work must be done within 120 days of applying. Follow Ofgem’s installer guidance and check it before each job.

How do you size the heat pump?

MIS 3005-D says the heat load calculation must follow BS EN 12831-1:2017. That standard sets how to calculate heat loss from a building. MIS 3005-D adds two rules.

• Use internal design temperatures no lower than those in its Table 1.
• Use an outside design temperature from its Table 2, column A (99%) or column B (99.6%). The percentage is the share of hours in a year that the temperature is at or above that value.

Source: MIS 3005-D, Tables 1 and 2 (taken from CIBSE Guide A). The table shows 4 of the 8 places in the standard.

For a heat pump that supplies all the space heating, the standard says to pick a unit that gives at least 100% of the calculated heat load, without help from a supplementary electric heater. It also says to avoid high temperature heat pumps unless the job needs a flow temperature above 55 °C. MCS also offers an online heat load calculator for MCS certified installers and those gaining certification.

How do you size the solar for a heat pump?

A heat pump adds to your electricity use. Divide the heat the home needs by the SCOP to find the extra electricity. Here is an example with made-up numbers. They are not data from a real home.

• Heat the home needs: 12,000 kWh a year.
• SCOP of the heat pump: 3.4.
• Heat pump electricity: 12,000 / 3.4 = 3,529 kWh a year.
• Other household electricity: 3,000 kWh a year.
• Total: 3,529 + 3,000 = 6,529 kWh a year.
• If the roof makes 900 kWh per kWp a year: 6,529 / 900 = 7.25 kWp.

This matches yearly totals only. Solar makes most power in summer, and a heat pump uses most in winter. A yearly match does not mean the home uses all its own solar. Model the hours of the year for your site. A generation and financial model can help with that, and shading analysis shows what the roof really gives.

What noise rule applies in England?

MCS 020 a) is the sound calculation for air source heat pumps installed as permitted development in England. It checks a limit of 37.0 dB(A) (LAeq,5mins) at each assessment position. An assessment position is 1 m outside the centre of a door or window of a habitable room in a neighbouring property.

The calculation has these inputs.

• Sound power level (Lw): from the maker’s data, in dB(A). Do not use the “low noise mode” value.
• Directivity (Q): Q2 for one reflecting surface, such as the ground. Q4 for two surfaces, Q8 for three. A reflecting surface is within 1 m of the unit and extends 1 m or more past it in two or more directions. More than three surfaces will not meet MCS 020 a).
• Distance (r): in metres, from the unit to the assessment position.
• Barrier loss (AB): 10 dB for a solid wall at least 18 mm thick with no view, 5 dB with a partial view, 0 dB with a full view. A thinner solid fence gives 5, 2.5 and 0 dB.

The formula is Lp = Lw + 10 x log10(Q / (4 x pi x r squared)) - AB.

Worked example from MCS

MCS gives this example. Lw is 60 dB(A), the unit is against one wall and the ground (Q4), the distance is 8.0 m, and a brick wall gives partial view (5 dB).

60 + 10 x log10(4 / (4 x pi x 8 squared)) - 5 = 31.97. MCS prints 31.96 in its working and shows 32.0 dB(A) in its table. That is below 37.0, so it passes.

Why the location matters

Take the same unit with no barrier and a distance of 6 m. This is our own example, worked with the MCS formula.

Each step up in Q adds about 3 dB, because 10 x log10(2) = 3.01. A unit that passes in the open can fail in a corner. Do the calculation for the real spot.

If the unit fails, it is not permitted development. MCS says you may be able to move it. MCS has guidance on mitigating noise.

What other planning limits apply to heat pumps?

The Planning Portal lists the permitted development limits for air source heat pumps in England. Here are some of them.

• The outdoor unit must be 1.5 cubic metres or less on a house, or 0.6 cubic metres on a block of flats.
• A detached house can have its first two heat pumps as permitted development. Other houses and flats can have the first one.
• Pitched roof installations are not permitted development. On a flat roof, every part must be at least 1 m from the roof edge.
• Listed building grounds and scheduled monuments are not covered.
• In a conservation area or World Heritage Site, the unit must not go on a wall or roof facing a highway.

Source: Planning Portal, air source heat pump. Rights can be removed by a planning condition or an Article 4 Direction.

MCS reports that the England changes took effect on 29 May 2025. They removed the rule about siting within 1 m of the boundary, raised the unit size limit from 0.6 to 1.5 cubic metres for houses, and allowed two units on detached houses. The Planning Portal says that from 28 May 2026, MCS 020 a) is the only permitted certification scheme. The two sources give different dates for the switch, so check the current Order before you rely on either. Source for the MCS dates: MCS news, 29 May 2025.

Wales has its own rules from 1 June 2026. See the MCS notice for Wales. It says Welsh work under permitted development must also follow MCS 020 a), and it mentions a 40 dB limit for two units. Check that notice before you work in Wales.

For a fuller guide, see our page on UK permitted development rights.

What about planning for solar panels?

The Planning Portal says solar panels on homes may be permitted development, with limits. The rule for solar equipment on a building was updated on 27 August 2026. There is a 12-month transition that ends on 27 August 2027. Until then you can follow either the old or the new rules.

Some limits appear in both the old and the new rules.

• On a pitched roof, panels must not go above the highest part of the roof (not counting the chimney).
• On a flat roof, the highest part of the PV equipment can be no more than 600 mm above the highest part of the roof.
• Panels are not covered on a building in the grounds of a listed building or on a scheduled monument.
• In a conservation area or World Heritage Site, panels must not go on a wall that faces a highway.

The new rules add limits for walls, balconies and plug-in solar. Read the current Planning Portal page before you quote.

What does MIS 3002 ask for at handover?

MIS 3002 Issue 6.0 was published on 18 March 2026. Contractors certified to it may follow it from that date, and it is mandatory from 18 June 2026. Some points for a combined job:

• The installer must record and show the total AC generation of the system.
• If the reading is used for billing or payment, the meter must be approved under the Measuring Instruments Directive (MID) and show its serial number on the front panel.
• The installer must register the system on the MCS Installation Database and generate an MCS certificate within 10 working days after commissioning. This happens only after the system is fully installed and commissioned.

Two things share the abbreviation “MID” in this standard. One is the Measuring Instruments Directive. The other is the MCS Installation Database.

Source: MIS 3002 Issue 6.0, clauses 5.7.1, 5.7.2, 6.3.2 and 6.3.4.

Check MCS’s heat pump installation documents for the matching heat pump steps. We did not use them here.

How does the Smart Export Guarantee fit in?

Ofgem says SEG licensees are electricity suppliers who pay small generators for power they export. Each licensee sets its own rate and contract terms. Any tariff must be above zero. You can apply to any licensee, not just your own supplier. Ofgem advises generators to shop around. Source: Ofgem, SEG for generators.

With a heat pump in the house, more of the solar power can be used at home, so less is exported. This page does not list supplier rates, because suppliers change them. Check each licensee’s own page.

Ready to design the PV side of a combined job? Book a SurgePV demo, or read more on UK solar compliance.

Frequently Asked Questions

Do commercial solar PV and heat pumps need MCS or DNO approval?

MIS 3002 covers solar PV up to 50 kWp DC output, and MIS 3005-D covers heat pumps up to 45 kWth each (70 kWth in total). The Boiler Upgrade Scheme accepts non-domestic buildings, but the installer must still be MCS certified. For grid connection, MIS 3002 says the installer must notify the distribution network operator (DNO) under EREC G98 or G99, and G99 applies above 16 A per phase.

What is MCS certification for heat pump and solar installations?

MCS is the Microgeneration Certification Scheme. It calls itself the UK’s quality mark for small-scale renewable energy technologies like solar panels, heat pumps and battery storage. Its standards also cover solar heating and biomass. The Boiler Upgrade Scheme requires installers to be MCS certified.

Can I claim the Boiler Upgrade Scheme grant for a heat pump paired with solar panels?

The grant is for the heat pump. It does not pay for solar panels. Ofgem lists the rules for the heat pump itself, such as replacing a fossil fuel or electric heating system and a minimum SCOP of 2.8 for air-to-water and ground source heat pumps. Solar panels are not named as a condition in the pages Ofgem and GOV.UK publish for the scheme.

How much is the Boiler Upgrade Scheme grant?

Ofgem lists £7,500 for air-to-water, ground source and water source heat pumps, £5,000 for biomass boilers and £2,500 for air-to-air heat pumps in homes. There is also £9,000 for air-to-water or ground source heat pumps in eligible off-gas grid properties, available from 21 July 2026 until 31 March 2027.

What noise limit applies to a heat pump under permitted development?

MCS 020 a) uses a limit of 37.0 dB(A) at the assessment position. That is 1 m outside the centre of a door or window of a habitable room in a neighbouring property. The installer must calculate the sound level from the unit’s A-weighted sound power level, its position, the distance and any barrier.

What does MIS 3005-D require for heat loss?

The heat load calculation must follow BS EN 12831-1:2017 and use at least the internal design temperatures in the standard. For a heat pump that supplies all the space heating, it must be chosen to provide at least 100% of the calculated heat load, without help from a supplementary electric heater.

Do I need planning permission for a heat pump or solar panels?

Often not in England, if all the permitted development limits are met. For heat pumps, the Planning Portal lists limits such as a 1.5 cubic metre unit on a house and MCS 020 a) compliance. The solar panel rules changed on 27 August 2026, with a transition period to 27 August 2027, so check the Planning Portal and your local authority.