MCS Certified Installers: What Certification Covers and How to Check One

The Microgeneration Certification Scheme, MCS, is an independent certification scheme for microgeneration installation companies and products¹. An MCS certified installer is an installation company that has been certified against MCS standards for a named technology, and that is contractually bound to install renewable technologies to industry-recognised standards while following recognised safety practices². Certification is company-level and technology-specific: a firm certified for solar PV is not thereby certified for heat pumps, and MCS will not normally consider a complaint where the installer was not certified for the technology installed at the time of the work.

Certification matters for money as well as quality. MCS is described as a UK Government-backed quality assurance scheme that certifies renewable products and installers³, and its certification is a requirement for accessing many UK government incentives². For the Boiler Upgrade Scheme in England and Wales, all installations must be carried out by MCS certified installers who are certified for heat pumps and/or biomass boilers⁴. The scheme covers small-scale renewables, broadly systems of 50 kW or smaller⁵, so most domestic solar, heat pump, battery, biomass and small wind work falls inside it.

MCS has redeveloped its installer scheme, rolling it out throughout 2026 and into early 2027⁴. The redeveloped scheme centralises complaints management inside MCS, strengthens financial protection, and replaces the separate consumer code membership requirement with an MCS Customer Commitment for installers who have transitioned. That transition is partway through, which means two slightly different sets of rules currently apply depending on which scheme a given company sits under.

What MCS certification is and what it covers

MCS certifies two separate things: products and installation companies. It describes itself as the UK's quality mark for small-scale renewables like heat pumps, and the mark shows that a product, or an installation that includes one or more certified products, meets requirements defined in the MCS standards. Certified installation companies are listed in MCS terminology as MCS Certified Contractors¹⁰.

MCS sets and maintains the technical standards for installations and products, certifies installers and products against those standards, issues MCS certificates for completed eligible installations, and assists certification bodies to review and address cases and consumer issues relating to installers or products¹. Certification bodies do the auditing; MCS owns the rules. It also facilitates Technical Working Groups, conducts research on industry developments and analyses updates to the standards referenced in its documents.

For the householder, certification is a statement about method and paperwork rather than about a particular product's output. All installers must follow the strict criteria set out in the MCS Installation Standards², and certified installers are required to use certified products. The one standing exception is battery storage: every certified installer delivering a certified installation must install an MCS certified product, except for battery storage¹⁰.

MCS is a company whose profits fund the MCS Foundation's activities, and it is based at Sci-Tech Daresbury in Cheshire¹¹. Leadership is changing: Ian Rippin leaves MCS in a full-time capacity at the end of 2026, with Lisa Cooke appointed managing director¹².

For the standards themselves, see the MCS installation standards, and for the paperwork that follows a job, your MCS certificate and handover pack.

What an MCS certified installer must do for you

The clearest statement of obligations is the MCS Customer Commitment. Certified installers must follow the Customer Commitment and all relevant MCS Standards, and MCS regularly checks compliance, financial stability, resourcing and customer protection⁷. Installers must provide the Customer Commitment to customers before a contract is signed¹³.

The Commitment is enforced through the MCS Installer Agreement, which creates a direct relationship between MCS and the installer. MCS has stated that an installer's ability to trade as MCS certified and to participate in the Boiler Upgrade Scheme can be withdrawn based on their delivery of the consumer experience.

Practical duties that fall out of this include:

• Keeping the customer fully informed about products and services, the installation timeline and any delays that may occur¹⁴
• Providing a quote that is clear and gives a full breakdown of what is being purchased¹⁴
• Giving clear information on how to contact the company with questions, concerns or complaints⁸
• Acknowledging a complaint within two working days and responding effectively⁷
• Taking responsibility for any issues with the installation and working with the customer to fix them quickly⁸
• Signposting customers to the MCS complaints process if they are unhappy with the outcome⁸
• Taking part in Alternative Dispute Resolution with the MCS provider where no agreed resolution is reached⁸
• Complying with all relevant, current consumer protection legislation, with products of good quality, fit for purpose and as described⁷

MCS also states the installer should issue the MCS certificate within 10 working days of completion, a deadline repeated across its consumer pages for solar PV, solar heating, air source and ground or water source heat pumps, biomass, micro CHP and battery storage⁶. Ofgem's Domestic RHI guidance set a 14 day deadline from commissioning¹⁵. The two figures come from different scheme rules and differ.

Consumer protection: what the redeveloped Installer Scheme changes

MCS has said it redeveloped its installer scheme to put consumer protection at its heart, and describes the result as set to transform the consumer protection landscape in the UK¹². The scheme is now rolling out across the MCS installer base¹⁶.

Three changes matter most to a household. First, complaints management has been centralised, with MCS handling complaints in-house and providing alternative dispute resolution where the parties cannot reach a resolution¹⁶. Second, financial protection has been strengthened: MCS states that consumers benefit from improved financial protections through enhanced requirements for providers and their products, guaranteeing remediation even if an installer goes out of business or refuses to carry out work, and providing a clear route to remediation¹⁷. Third, MCS is contacting every recipient of an MCS certified installation, both to verify certificates and to monitor each installer's compliance with the Customer Commitment¹⁶.

That is the scheme's own claim about its own scheme, and the phrasing is forward-looking. The transition is not complete. MCS has published an interactive guide covering everything certified installers need to know about moving to the redeveloped scheme¹⁶, and the transition phase is due to end on 31 March 2027, by which date all MCS certified installers must operate under the redeveloped scheme⁹.

Which technologies and system sizes fall within the scheme

MCS certifies, quality assures and provides consumer protection for microgeneration installations and installers, covering small-scale renewable electricity technologies such as solar photovoltaic panels, biomass, wind, heat pumps and heat products⁵. Its own material describes coverage running from solar panels to heat pumps to small wind turbines, and separate consumer pages exist for micro CHP and battery storage.

Size is the main boundary. MCS is described as the quality assurance organisation for microgeneration, meaning small-scale renewable technologies of 50 kW or smaller⁵, and MCS product certification uses a limit of 50 kW for electrical technologies¹⁰. Licence conditions for eligible installations require that installations of 50 kilowatts or less generating from combined heat and power, solar photovoltaic or wind are certified under MCS or an equivalent scheme and installed by an MCS or equivalent installer¹⁸. Feed-in Tariff guidance applied the same logic to solar PV or wind with a declared net capacity up to 50 kW, and to CHP up to a total installed capacity of 2 kW¹⁹.

At the upper end for heat, official heat pump statistics note that installations not covered by MCS are heat pumps installed with a thermal output larger than 45 kW, and the majority of installations in new-build properties²⁰.

The new-build exclusion is significant for households buying a home with renewables already fitted: the MCS Foundation's position is that housebuilders should ensure every installation is delivered by an MCS certified installer to MCS standards, which implies it is not currently universal. A certificate may simply not exist for a system installed during construction.

Certification and government incentives: why it matters for grants

MCS certification is a route to many consumer grants and incentives, and a requirement for accessing many UK government incentives². Energy Saving Trust puts it plainly: an MCS installer is needed to take advantage of any available grants²¹. The MCS certificate itself is the artefact that grant administrators want, because it is a record that the installation was done by a certified installer using certified products, and it is required when accessing some grants and incentives²².

For the Boiler Upgrade Scheme, Ofgem requires that the business is certified to install the relevant technology under MCS²³, and that installers are certified to install heat pumps and/or biomass boilers⁴. Where a property owner is contacted by MCS for additional checks, Ofgem guidance asks them to aim to respond within seven days²⁴. MCS may also make a short routine verification contact on behalf of Ofgem, by email or on 0333 103 8198²⁵. For ECO4, MCS's own guidance states that to be eligible the installer must be MCS certified²⁶. MCS is additionally an approved certification scheme for the Clean Heat Market Mechanism.

Two administrative points are easy to miss. Additional users on a Boiler Upgrade Scheme installer account must be direct employees of the registered MCS installer and not subcontractors, and updates to the MCS list can take up to 21 days after account activation⁴. A company that has just been certified may therefore not appear on a search immediately. There is fuller detail on installer requirements for grants.

How to check an installer is MCS certified

Checking is free and takes minutes. MCS states that certification can be verified through its Find an Installer online tool or by contacting its customer support helpdesk²⁵, on 0333 103 8130²⁷. MCS also advises householders to look for the MCS Certified Mark as reassurance that an installer is certified²⁸. Local authority guidance directs residents to the same government-endorsed scheme to find certified installers and to get at least three quotes from reputable installers²⁹.

Three things are worth confirming rather than assuming:

1. The company, not the individual. Certification is held by the installation company, described in MCS terminology as a certified contractor¹⁰. A named engineer is not separately certified by MCS.
2. The technology. MCS will only consider a complaint where the installer was certified for the technology they installed when they entered into the contract³⁰. Certification for solar PV does not cover a heat pump.
3. The date. Certification must be in place at the time of the contract and the installation, not merely at the time of the sales visit.

Energy Saving Trust and MCS guidance both suggest approaching at least three MCS certified installers for a heat pump³. Where a company installs under another firm's certification, see MCS umbrella schemes, and for wider due diligence, checking an installer before you sign.

What MCS certification does not guarantee

Certification is a quality assurance scheme, not a performance warranty, and an independent report on the heat pump transition is blunt about the limits. MCS requires installers to provide a design-stage prediction of system efficiency, not to verify actual performance, and it does not require remediation of systems that are underperforming relative to their design³¹. The same report notes that weather compensation is not mandatory under current MCS requirements, that third party non-modulating controls are not prohibited, and that MCS specifies handover documentation but not the quality of verbal explanation, household understanding, structured follow-up or ongoing support³¹.

Read together, that means a system can be fully compliant, fully certified and still deliver less than the figure on the quote, with no MCS mechanism that compels the installer to put the efficiency right. The scheme's strongest lever is at the level of conduct and compliance: if an installer is not willing or able to install to a high standard in compliance with MCS requirements, the ultimate sanction is withdrawal of the installer's MCS certification³⁰. That protects future customers more directly than it repairs an existing installation.

Other gaps follow from scope. Battery storage installations do not require a certified product¹⁰. Heat pumps above 45 kW thermal output and most new-build installations sit outside the scheme altogether²⁰. And certification says nothing about price: quotes remain installer-quoted, and comparing them is a separate exercise covered in comparing installation quotes and performance estimates and savings claims.

For a household pursuing energy independence, the honest summary is that MCS reduces the risk of a badly designed or badly documented system and unlocks grant money, but it does not remove dependence on the installer's competence, on the manufacturer's product support, or on the grant schemes themselves continuing.

Consumer codes: what the transition changed

Historically the two schemes were linked. A requirement of companies wanting to gain MCS certification was that they were members of a CTSI Approved Consumer Code of Practice scheme in the first instance³², and installation companies had to be members of a Chartered Trading Standards Institute approved consumer code for the microgeneration sector³³. Ofgem guidance for Domestic RHI states that MCS installation companies working with domestic customers must also be a member of a Consumer Code approved by the Trading Standards Institute²⁷.

That has now changed for installers who have moved across. The government response on Boiler Upgrade Scheme amendments records that MCS has replaced the requirement for contractors to be members of a CTSI approved consumer code with its own Customer Commitment³⁴. Ofgem's July 2026 installer guidance states that installers operating under the redeveloped scheme are no longer required to hold a separate consumer code membership in order to deliver work under the Boiler Upgrade Scheme, while installers that have not transitioned must still hold membership with one of the other two approved codes of practice, HIES and RECC⁴.

The documents do not all read the same way. Ofgem's April 2026 property owner guidance still states that installers working with consumers must be MCS certified and members of a consumer code approved by the Secretary of State³⁵, and its April 2026 installer guidance says installers must continue to hold membership with one of the two approved consumer codes until further notice²⁴. The two approved consumer codes currently recognised by MCS are RECC and HIES¹³. MCS shares complaints information with Code Sponsors on a two-weekly basis³³. See RECC and HIES compared for what each code offers.

Complaining about an MCS certified installer

MCS defines a complaint as an expression of dissatisfaction, however made, about an installation, the standard of service, actions or lack of action by the installer, its staff, or those acting on its behalf, affecting a customer⁸. The process has an order to it.

1. Complain to the installer first. MCS is the single point of contact for complaints about certified installers or installations, after an issue has been raised with the installer³⁰. Certified installers must acknowledge within two working days⁷. MCS suggests 14 days is a reasonable maximum time to expect a response³⁶. Ofgem guidance for the code route says the installer should be given at least 10 working days to resolve it²⁷.
2. Escalate to MCS. Complaints go to mcscomplaints@mcscertified.com or 0333 103 8130³⁷. MCS acknowledges within 5 working days³⁶.
3. Investigation. MCS will speak to third parties on the householder's behalf, carry out a technical review of the installation if needed, and work with the installer to reach a resolution³⁶. Details of the complaint are shared with the installer, the certification body and the Consumer Code if applicable⁸.
4. Alternative Dispute Resolution. Certified installers must take part in ADR with the MCS provider where no agreed resolution is reached through the complaints process⁸.

MCS will consider complaints about system performance and design, quality of work, incomplete installation, delayed installation, commissioning and handover, installer conduct, damage to property, mis-selling, contractual issues, issues with product, and Customer Commitment breach³⁰. A separate whistleblowing route covers reports of illegal, unethical or harmful behaviour from a certified installer, and MCS states that lessons learned will be used to improve scheme oversight and maintain standards³⁷.

Time limits differ between documents. MCS states it will not consider a complaint where the installation was completed over six years ago, five years in Scotland, because of consumer protection legislation requirements³⁰. Ofgem's Domestic RHI guidance states that for MCS certified installations the limit is no more than two years after the date the system was commissioned²⁷. These are different limits from different rulebooks; both are current.

Certification lapsing or being suspended does not close the door. Temporary suspension from the scheme does not remove the right to complain, and where an installer is no longer certified or no longer trading MCS states it can still review the complaint and explain what options are available³⁰. Citizens Advice confirms the general position that where a complaint to the installer has not produced a satisfactory response, the scheme can be asked for help³⁸. Further detail sits on complaining about an installer and when your installer goes bust.

What certification means for household energy independence

An MCS certified installation is the normal route into self-generation in the UK: it is the gateway to grants such as the Boiler Upgrade Scheme and ECO4, and the certificate is the document that proves the system exists to the standard claimed². Using a certified installer is described by MCS as giving protection if something were to go wrong²⁸.

The dependencies that remain should be stated as firmly. The household still depends on the installer's design judgement, since MCS checks a design-stage prediction rather than measured output³¹. It depends on the manufacturer for the product and its support. It depends on MCS itself for the complaints route, and on the redeveloped scheme's financial protections actually being in force for the particular installer used, which is not yet universal before the March 2027 transition deadline⁹. And it depends on grant schemes continuing: MCS's own consumer material records that ECO4 is set to end on 31 December 2026. Certification narrows the risk of a bad installation. It does not make a household independent of the companies and schemes that stand behind it. The wider picture is set out on the installers and retailers guide and in installers and energy independence.