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

MCS certification is the quality mark behind almost every small-scale renewable installation in the UK, from heat pumps and solar panels to biomass boilers and wind. The Microgeneration Certification Scheme is an independent certification scheme for microgeneration installation companies and products, and its role is to make sure a firm installing renewable technology in your home works to consistent, industry-recognised standards¹. For a householder, that matters twice over: it is the main assurance that the design and installation of a system meet recognised standards, and it is a condition of the government grants that pay towards the work, including the Boiler Upgrade Scheme³.

Certification is not a single badge covering everything. An installer is certified for specific technologies, and the products they fit must themselves be certified. A company certified for solar PV is not thereby certified for heat pumps, and a heat pump installed by an uncertified firm will not attract a grant. This page explains what the scheme covers, what a certified installer owes you, how to check a company's certification, and what to do when something goes wrong.

What the MCS scheme is and what it certifies

MCS, the Microgeneration Certification Scheme, is described by Ofgem as "an independent certification scheme for microgeneration installation companies and products"². Its roles include setting and maintaining technical standards for installations and products, certifying installers and products against those standards, issuing MCS certificates for completed eligible installations, and assisting certification bodies to review and address cases and consumer issues relating to installers or products².

Two things are certified, and a household needs both. The installer must be MCS certified, and the product they fit must be MCS certified too. MCS states that an installation counts as certified "if the installation has been carried out by an MCS certified installer" using certified products⁴. The installer must also have been certified for the specific technology at the right moments: MCS will only consider a complaint where "the installer was MCS certified for the technology they installed when they entered into a contract with you" and was still certified "at the time of the installation"³.

For a household planning heat pumps, solar or biomass, this structure is the foundation of the whole consumer protection chain described below. It is also the lens through which grants are paid, as later sections set out.

What a certified installer must do for you

Certification comes with obligations the installer owes you directly, written into the MCS Installation Standards and the MCS Customer Commitment. All installers "must follow the strict criteria outlined in the MCS Installation Standards"¹, and MCS states that certified installers "install renewable technologies to industry-recognised standards"¹. The MCS Installation Standards themselves are covered in detail elsewhere on this site.

The Customer Commitment, first issued in January 2025, "outlines the responsibilities certified installers have towards you as their customer"⁶. Installers "must provide the Customer Commitment to customers before a contract is signed"⁹, so a copy belongs in your hands before anything is signed. Under it, a certified installer must:

• Ensure you are "fully informed of their products and services, the installation timeline, and any delays which may occur"⁶
• Give "clear information on how to contact you with any questions, concerns, or complaints"⁸
• "Take responsibility for any issues with the installation and work with your customer to fix them quickly"⁸
• "Acknowledge a complaint within two working days and respond effectively"⁹
• Comply "with all relevant, current consumer protection legislation", with products "of good quality, fit for purpose and as described"⁹

MCS checks this is not just paper. Certified installers "must follow this Customer Commitment and all relevant MCS Standards", and "MCS will regularly check" their compliance, financial stability, resourcing and customer protection⁹. The quote itself is part of the duty: for solar heating, MCS describes "the quote you will be provided for your solar heating installation, which will be clear and provide a full breakdown of what you're purchasing"⁶.

The redeveloped Installer Scheme and what it changes for consumers

MCS has redeveloped its installer scheme, with the transition "rolled out throughout 2026 and into early 2027"¹⁰. As of September 2026 the redeveloped scheme is "now rolling out across the MCS installer base"¹¹, and the transition phase is due to end by 31 March 2027, by which date all MCS certified installers must operate under the redeveloped scheme¹¹.

The headline change is financial protection. Under the redeveloped scheme, consumers benefit from "improved financial protections, guaranteeing remediation even if an installer goes out of business or refuses to carry out work"¹², providing "a clear route to remediation"¹². That addresses the scenario householders fear most: paying a deposit or having a system fitted, then finding the company has dissolved and there is nobody left to fix faults.

Complaints handling has also moved in-house. Since 10 September 2026, MCS manages complaints itself and provides alternative dispute resolution where the parties cannot reach a resolution¹¹. MCS describes the change in sweeping terms: "The consumer protection embedded throughout MCS' robust quality assurance scheme will generate better outcomes for consumers, for industry, and for the transition to home-grown energy"¹². MCS has also said it "will be contacting every recipient of an MCS certified installation" as part of its verification work¹¹.

Technologies and system sizes within the scheme

MCS covers microgeneration: small-scale renewable and low-carbon technologies. The scheme "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 products"¹³. Another official description calls MCS "the leading quality assurance organisation for microgeneration (small scale renewable 50kW or smaller) technologies"¹⁴.

The size limits matter because they define where certification stops:

Official licence conditions state that for installations of 50 kilowatts or less generating from combined heat and power, solar photovoltaic or wind, "the installation is certified under MCS or an Equivalent Scheme, and have been installed by an MCS or equivalent installer"¹⁵. Heat pump statistics published by the government note that "the installations that would not be covered by MCS are heat pumps installed with a thermal output larger than 45kW and the majority of installations in new-build properties"⁵. Most domestic systems sit comfortably inside these limits, but a large home with a big heat pump, or a new-build development, may fall outside the scheme.

Within the scheme, each technology has its own standards. A certified micro CHP installation, for example, will be "designed and installed in accordance with MCS Standards", with certified installers using "MCS certified micro CHP systems", meaning "the product being used has been tested for quality"¹⁷.

Certification and grants: why MCS matters for the money

For most households, the practical importance of MCS certification is that the money depends on it. MCS states that certification "is a requirement for accessing many UK government incentives" and "a route to many consumer grants & incentives"¹.

The clearest example is the Boiler Upgrade Scheme. Ofgem's guidance is unambiguous: "All BUS installations must be carried out by MCS-certified installers"¹⁸, and installers "must be MCS certified and be certified to install heat pumps and/or biomass boilers"¹⁰. To hold a BUS installer account, "your business must be certified to install the relevant technology under the Microgeneration Certification Scheme (MCS)"¹⁹. The same rule reaches back through earlier schemes: Feed-in Tariffs required "MCS-certified equipment installed by an MCS-certified installer" for solar PV or wind with a declared net capacity up to 50kW, or CHP up to a TIC of 2kW¹⁶, and the Domestic RHI required installers "to issue a certificate for an installation within 14 days of commissioning"²⁰.

MCS certification also connects to newer policy machinery. MCS "is an approved certification scheme for the Clean Heat Market Mechanism", and heat pumps registered on the MCS Installation Database are by that fact MCS certified, installed "by MCS certified installers who are using certified products" to "industry-recognised standards"²¹. The government's response on Boiler Upgrade Scheme amendments records that "MCS have replaced the requirement for contractors to be members of a Chartered Trading Standards Institute (CTSI) approved consumer code with their own 'Customer Commitment'"²², a change explored in the next section but one.

The consequence for a householder is simple: an uncertified installer is not a cheaper route to a grant-funded system, it is a route to no grant at all. The installer requirements for grants are covered in full on their own page.

Verifying your installer holds MCS certification

Checking is straightforward and free. MCS states: "You can check whether an installer is MCS certified by checking our Find an Installer online tool or contacting our Customer Support Helpdesk"²³. Official guidance for householders points to the government-endorsed Microgeneration Certification Scheme for finding certified installers, and to at least three quotes from reputable installers before committing²⁴.

What to check, in order:

1. The company is certified at all, using the Find an Installer tool or the Customer Support Helpdesk²³.
2. The company is certified for the technology you want. Certification is technology-specific, and BUS requires the business "be certified to install the relevant technology"¹⁹.
3. The certification was in place when you signed. MCS will only consider complaints where the installer "was MCS certified for the technology they installed when they entered into a contract with you"³.
4. The product is certified too. Certified installers must use certified products, with one exception noted below⁴.

One timing quirk is worth knowing if you are checking a firm against a grant scheme list: "Updates to the MCS list can take up to 21 days after account activation"¹⁰, so a newly certified firm may not appear immediately on every government list.

Be scam-aware when checking. MCS warns householders to be careful of impostors: "MCS will never cold call you", and "you will not be asked to purchase items like warranties from us"²³. MCS may legitimately contact you after an installation, through its Customer Insights team, "to verify your MCS certificate and make sure the installation process was delivered to your satisfaction"²³, and for Boiler Upgrade Scheme purposes it may contact you "for a short, routine verification on behalf of Ofgem either via email or phone (0333 103 8198)"²⁵. Property owners contacted for these checks "should aim to respond within seven days"²⁶.

What certification does not guarantee

Certification is a standards mark, not a performance promise, and the limits are worth stating plainly.

• It does not verify actual performance. MCS "requires installers to provide a design-stage prediction of system efficiency, not verify actual performance", and "does not require remediation of systems that are underperforming relative to their design"²⁷. The performance estimates in your quote are predictions, not guarantees.
• Not every product must be certified. All MCS certified installers delivering certified installations "must install an MCS certified product, except for battery storage"⁴.
• It does not cover everything. Heat pumps above 45kW thermal output and most new-build installations fall outside MCS⁵.
• Timing can void the protection. If your "installer was not MCS certified for the renewable technology you've had installed at the time of the installation", MCS's ability to help is limited³.
• Handover quality is only partly specified. MCS "specifies handover documentation but not the quality of verbal explanation, household understanding, structured follow-up or ongoing support"²⁷.
• Design choices are not all mandated. Weather compensation "is not mandatory under current requirements of the Microgeneration Certification Scheme (MCS)", and "third party non-modulating controls are not prohibited"²⁷.

The ultimate sanction does exist: "If an installer is not willing or able to install to a high standard in compliance with MCS requirements, the ultimate sanction of MCS is to withdraw the installer's MCS certification"³. But a withdrawn certificate is a disciplinary tool, not compensation for a household whose system underperforms.

How the transition altered consumer codes

For years, a condition of MCS certification was membership of a consumer code approved by the Chartered Trading Standards Institute. The Renewable Energy Consumer Code itself states that "a requirement of companies wanting to gain MCS certification is that they are members of a CTSI Approved Consumer Code of Practice scheme in the first instance"²⁸, and Ofgem's guidance has long said that "MCS installation companies working with domestic customers must also be a member of a Consumer Code approved by the Trading Standards Institute"⁷.

The redeveloped Installer Scheme changes this, but only for installers that have transitioned. Ofgem's installer guidance states that installers operating under the redeveloped scheme "are therefore no longer required to hold a separate consumer code membership in order to deliver work under the Boiler Upgrade Scheme"¹⁰. Installers that have not transitioned "must still hold consumer code membership with one of the other two approved codes of practice (HIES and RECC)"¹⁰. MCS's own guidance to installers says the same: installers "must continue to hold membership with one of the two approved consumer codes (RECC or HIES)" for Boiler Upgrade Scheme work, until further notice²⁶. The two approved consumer codes currently recognised by MCS are those two²⁹.

The position during the transition is therefore mixed, and the Boiler Upgrade Scheme guidance for property owners still describes the combined requirement: "installers working with consumers must be MCS-certified and members of a consumer code approved by the Secretary of State"¹⁸. In practice, during 2026 and early 2027 a householder may encounter both arrangements. The RECC and HIES pages cover what each code requires separately.

Making a complaint against an MCS certified installer

The process has a defined order, and it starts with the installer. MCS is "your single point of contact for complaints about MCS certified installers or installations, after an issue is raised with your installer first"³. Give the installer reasonable time to respond: "14 days is a reasonable maximum time to expect a response"³⁰. Installers must "acknowledge a complaint within two working days and respond effectively"⁸.

If that fails, escalate to MCS. Its scope is broad, covering system performance and design, quality of work, incomplete or delayed installation, commissioning and handover, installer conduct, damage to property, mis-selling, contractual issues, product issues and Customer Commitment breaches³. During the investigation, "MCS will speak to third parties on your behalf, carry out a technical review of the installation if needed, work with your installer to reach a resolution"³⁰. MCS will acknowledge your complaint within 5 working days³⁰, and it will "share details of the complaint with you, your certification body and your Consumer Code (if applicable)"⁸. If agreement cannot be reached, installers must "take part in Alternative Dispute Resolution (ADR) with our provider"⁸.

Time limits apply. For MCS certified installations, complaints must be made "no more than two years after the date that the system was commissioned"⁷. Separately, MCS cannot help where "your installation was completed over six years ago (five years in Scotland), due to requirements under The Consumer Protection..." regulations³. Where a complaint concerns a consumer code member, the code expects at least 10 working days to resolve it before being contacted⁷.

Two special cases are worth knowing. First, a dissolved or suspended firm is not a dead end: "We can still review your complaint and let you know what options are available" where the installer is no longer certified or trading³, and temporary suspension "does not remove your right to complain"³. Second, whistleblowing: "you can make a whistleblowing complaint, reporting information about illegal, unethical, or harmful behaviour from an MCS certified installer, by email to mcscomplaints@mcscertified.com or on 0333 103 8130"³¹, and "any lessons learned will be used to improve Scheme oversight and maintain standards"³¹.

Certification and its role in household energy self sufficiency

MCS certification sits at the centre of a household's route to generating its own heat and power, but it is worth being clear about what independence it does and does not deliver.

What it supports: a certified installation is the gateway to grant funding for heat pumps and biomass¹⁰, to registration on the databases that underpin schemes such as the Clean Heat Market Mechanism²¹, and to a complaints and remediation process that survives an installer's failure¹². A household with a certified heat pump or solar array is measurably less dependent on imported heat and purchased electricity, and the certification chain is what makes that installation bankable, insurable and grant-eligible.

What dependence remains: the scheme certifies the installer and the product, not the outcome. Performance depends on design and your own usage, and MCS does not verify actual performance or require remediation of underperforming systems²⁷. The installer remains a single point of dependence for aftercare, and although the redeveloped scheme guarantees remediation where an installer goes out of business¹², the household still depends on MCS, its certification bodies and its dispute process to enforce that. Certification also does not remove dependence on the manufacturer's warranty for the product itself, or on the grid for the electricity a heat pump draws.

Used well, the scheme is the strongest consumer protection available in this market. Checked before you sign, and understood for what it does and does not promise, it is the difference between a home energy installation you can rely on and one you can only hope for.