How long an MCS installer has to give you your certificate

So the working answer to "how long" is 10 working days from completion, with 14 days from commissioning appearing in scheme rules as an outer limit. The two figures measure slightly different things: completion of the work, and commissioning of the system. In practice they usually fall on the same day, which is why both numbers circulate.

The certificate matters beyond paperwork. It is the evidence a grant scheme, a feed-in tariff application or a future buyer will ask for, and it is generated from the database entry the installer is required to make. If the installer never registers the job, no certificate exists to send.

What the MCS certificate is and who issues it

MCS is a certification scheme for microgeneration installation companies and products⁶. It 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 products⁷. Certification is voluntary, and MCS describes itself as a voluntary certification scheme in the sector⁸.

The certificate itself is not written by the installer by hand. The installer registers the installation on the Microgeneration Installation Database and the certificate is generated from that record. NAPIT sets out the obligation plainly: the installer is required to register the installation on the Microgeneration Installation Database within 10 days of commissioning the system and supply the MCS Certificate generated from the database⁹. The same wording appears in its household advice¹⁰.

MCS describes the certificate as a record that the installation has been done by a certified installer using certified products¹. Home Energy Scotland calls MCS certification a mark of quality that demonstrates compliance of both products and installation contractors with recognised industry standards¹¹. Product certification itself is described by MCS as a mark of quality, reached through testing, audit and certification¹².

For a household, the certificate is the paper trail that connects the work to a recognised scheme. It is not a performance guarantee, and it does not by itself promise that a heat pump will hit a predicted efficiency figure or that a solar array will generate a stated number of kilowatt hours.

The deadline: certificate within 14 days of commissioning

The 14 day figure comes from scheme rules rather than from MCS's consumer pages. The Barcud Solar Panel Installation Scheme Specification states that MCS commissioning certification is to be issued to the Employer within 14 days of commissioning². That is a contractual deadline in a funded scheme, and it sits alongside the same document's requirement that registration on the MCS Installation Database happen no later than 10 working days after commissioning².

The consumer-facing figure is consistently 10 working days. MCS gives it for solar heating¹, for air source heat pumps¹⁴, for battery storage¹⁵, for micro CHP¹⁶, for ground and water source heat pumps¹⁷, for solar photovoltaic¹⁸ and for biomass¹⁹. The repetition across technology pages is the clearest signal of what a household should expect.

There is a longer deadline in the MCS Customer Commitment, which requires an installer to give the household specified documents within 30 calendar days of the completion of the installation³. That is a backstop for the wider handover pack, not the certificate alone, and it should not be read as licence to sit on the certificate for a month.

The gap between 10 working days and 14 calendar days is small but real. Ten working days is a fortnight in most weeks, so the two rules usually expire within a day or two of each other. Where a job is commissioned on a Friday and the paperwork runs into a bank holiday, the calendar version can bite first.

Registration on the MCS Installation Database: 10 working days

Registration is the step that creates the certificate, and it is the installer's duty, not the household's. NAPIT's household guidance states that the installer is required to register the installation on the Microgeneration Installation Database within 10 days of commissioning the system and supply the MCS Certificate generated from the database⁹. The Barcud specification uses working days rather than calendar days for the same step².

The database entry is what grant bodies and tariff administrators check. Ofgem's Boiler Upgrade Scheme guidance for installers lists the MCS installation certificate number among the information required for a voucher redemption application²⁰. Without a certificate number, a voucher application cannot be completed properly.

Timing matters for grant applications too. Ofgem guidance states that installers must ensure the voucher application is properly made within 120 days of the commissioning date on the MCS certificate, for retrospective applications²⁰. A late certificate compresses that window.

There is a separate administrative lag worth knowing about. Ofgem notes that updates to the MCS list can take up to 21 days after account activation²⁰. That is about the installer's own listing, not the household's certificate, but it explains why a newly certified business may not appear in a search immediately.

What to do if the certificate is late

The first step is the installer, because the installer holds the database account and the obligation. MCS provides a certificate request form for a copy or amendment of an MCS certificate, which sends the request to its Customer Support team²¹. The general contact number is 0333 103 8130⁵.

If the installer does not respond, the complaint route opens. Ofgem's guidance on installer complaints says that a household should have given the installer at least 10 working days to resolve the matter before contacting the consumer code, and that if the complaint is not resolved the household can approach the MCS Administrator, who will advise how to make a complaint about the MCS installer²². MCS itself states that it will acknowledge a complaint within 5 working days⁴, and that most complaints are fully resolved within 8 weeks²³.

For MCS certified installations, Ofgem states that a complaint must be made no more than two years after the date that the system was commissioned²². That is a hard limit and it runs from commissioning, not from the date the household first noticed a problem.

Certificates issued before completion are a known trap. Ofgem's feed-in tariff guidance is explicit: do not accept MCS certificates that are issued before completion as these are ineligible and will make you ineligible for the scheme²⁴. The same warning appears in the community and schools factsheet, which states that MCS certificates should only be issued once the installation is fully installed and commissioned, and that certificates issued before completion will not be accepted²⁵. A certificate dated before the work finished is worse than a late one.

MCS checks after installation: the seven-day response period

MCS runs post-installation checks on a sample of jobs, and these have their own clock. Ofgem guidance for property owners states that property owners contacted for MCS checks should aim to respond within seven days⁵. The check is a verification exercise, not a complaint, and a slow response can hold up the process.

The seven-day period sits alongside the installer's own complaint handling duties. MCS requires certified installers to acknowledge a complaint within two working days and respond effectively²³. Where a complaint escalates to the CWISC guarantee, the concern is acknowledged within 2 working days of receipt²⁶.

Product certification has its own corrective action deadline: within 45 days of the factory audit¹². That applies to manufacturers rather than households, but it shows the scheme's general pattern of short, fixed response windows.

For a household, the practical point is that post-installation correspondence from MCS or a scheme administrator is time-limited. A seven-day response window is short enough that post alone may not be enough, and email or the online route is quicker.

Complaining about an installer or certificate: the two-year window

The complaint window is the single most important deadline on this page. Ofgem states that for MCS certified installations, a complaint must be made no more than two years after the date that the system was commissioned²². MCS's own consumer complaints guidance sets a longer limitation for its own process, stating that a complaint falls outside scope where the installation was completed over six years ago, or five years in Scotland, due to requirements under the Consumer Protection Act 2015²⁷.

Those two figures are not in conflict so much as different gates. The two-year figure is the route through the consumer code and the MCS Administrator for an MCS certified installation. The six-year and five-year figures describe the outer limitation on MCS's own complaints handling. A household with a problem three years after commissioning may still have a route through MCS even though the consumer code window has closed.

MCS gives delayed installation as an example of a complaint it handles²³. Its process acknowledges a complaint within 5 working days and resolves most within 8 weeks⁴. Complaints can be sent to mcscomplaints@mcscertified.com⁴.

For other technologies the paperwork differs. HETAS, which covers stoves, biomass and solid fuel, issues a Certificate of Compliance rather than an MCS certificate, and states that a household has two months from installation completion to contact support for a free replacement, after which a duplicate certificate fee applies²⁸. That two-month window is much tighter than the MCS complaint limits and is worth noting for anyone with a solid fuel installation.

Checking an installer and avoiding the scams around certification

MCS provides a Find an Installer online search tool, and the Customer Support Helpdesk can confirm whether a business is certified³⁰. Checking is free, whether through the search or by calling 0333 103 8130¹⁸. The search shows which technologies an installer is certified for, which matters because certification is technology-specific.

MCS states that it will never cold call a household, and that households will not be asked to purchase items such as warranties from MCS³⁰. Any approach that claims otherwise is not consistent with how MCS says it operates, and MCS publishes scam awareness guidance for households³⁰.

Certification is also a condition of some funded work. The Warm Homes: Local Grant policy guidance states that MCS certification is required for low carbon heating measures, with the exception of high heat retention storage heaters covered by PAS 2030³¹. That means the certificate is not only a record for the household but a condition of the funding in the first place.

For households weighing up which registration to look for, the wider picture is covered in MCS certified installers and in the pillar guide to home energy installers and retailers. The certificate's place in the handover pack is set out in your MCS certificate and installation handover pack, and the standards behind the work in the MCS installation standards. Where a certificate never arrives and the installer stops responding, the escalation route is described in complaining about an installer.

What the certificate does and does not do for energy independence

The certificate is a record of process, not a promise of output. MCS describes it as evidence that the installation was done by a certified installer using certified products¹, and Home Energy Scotland describes MCS certification as a mark of quality demonstrating compliance with recognised industry standards¹¹. Neither statement is a guarantee of performance.

That distinction matters for a household aiming at energy independence. A certified installation of a heat pump, solar array or battery gives the household a system it can operate and maintain on its own terms, and the certificate is what makes the installation legible to grant bodies, tariff administrators and future buyers. What it does not do is remove the remaining dependencies: a grid connection for import and export, a supplier for billing and export payments, and in many cases a manufacturer's app or cloud service for monitoring and control. A battery installation certified under MCS still depends on the manufacturer's software for some functions¹⁵.

The certificate also does not transfer the installer's obligations to MCS. MCS certifies and provides consumer protection, but the workmanship obligation sits with the installer, and the complaint route runs through the installer first, then the consumer code, then the MCS Administrator²². Where an installer has ceased trading, the certificate remains useful as a record but the warranty position changes, and that is a separate question from certification.