What is MCS certification? A buyer's guide

Written by Miles Sharples, Managing Director

Two decades in retrofit, delivered at scale across the UK for councils, housing associations and energy suppliers. About Miles · LinkedIn

MCS is the UK’s certification scheme for small scale renewable technologies, including solar panels and home batteries. An MCS certified installer has been assessed by an independent, UKAS accredited certification body and keeps being checked for as long as they hold the certificate. For solar PV, the MCS certificate you get at the end is usually what an energy supplier asks to see before it pays you for the electricity you export.

This guide explains what sits behind those three letters, the paperwork you are entitled to, where MCS protects you and where it does not, and how to check any installer before you sign.

What MCS is, and who runs it

MCS stands for the Microgeneration Certification Scheme. The UK Government set it up in 2006, and it became independent of government in 2018. It is run by the MCS Service Company, which is owned by a charity, The MCS Foundation. So it is not a government scheme, although the government and Ofgem both use its installation records.

MCS covers small scale solar PV, solar heating, heat pumps, biomass, small wind turbines, micro CHP and battery storage. For electrical technologies such as solar PV and batteries, small scale means up to 50 kW. A home system is a fraction of that. A large commercial roof can be above it, and then MCS does not apply.

Installers, products and installations

MCS certifies three different things, and it helps to keep them apart.

Installers. MCS does not certify installers itself. Independent certification bodies assess and certify them, and each one is accredited by the United Kingdom Accreditation Service (UKAS) to an international standard, ISO/IEC 17065. UKAS checks the certification body and the certification body checks the installer, which is why the right phrase is an MCS certified installer. Under the redeveloped scheme, MCS also runs its own checks on each business, such as its financial performance, insurance, directors and complaint history. To be certified for a technology for the first time, an installer must pass a site based assessment of at least one of its own installations of that technology, and its business processes are checked too. After that come regular site assessments, at least yearly for each technology in the first two years and then based on risk. The certification body can suspend or withdraw certification, and it is granted technology by technology, so the certificate lists exactly what is covered.

Products. On an MCS solar installation the panels must be listed in the MCS product directory, pitched roof mounting kits must be certified, and everything must be new and unused. Batteries are the exception. MCS does not certify battery products, so there is no such thing as an “MCS certified battery”. The battery installation is certified, and the equipment needs the manufacturer’s declaration of conformity.

Installations. When your job is finished, the installer registers it on the MCS Installation Database, which holds a record of certified small scale installations in the UK going back to 2008. Your MCS certificate is raised from that record.

What the standards cover

For solar PV the installation standard is MIS 3002. It covers grid connected solar PV on permanent buildings up to 50 kWp, and sets the rules for designing and sizing the system, installing and commissioning it, and handing it over. The written performance estimate you see before you sign is part of MIS 3002 under the original scheme, and has its own standard, MCS 032, under the redeveloped scheme.

For batteries it is MIS 3012, which MCS launched in November 2021. It covers home batteries up to 50 kW fitted behind the meter in permanent buildings, but not off grid systems, uninterruptible power supplies or batteries in vehicles. It sorts batteries into four classes, from an all in one unit to a system the installer assembles from different makers’ parts, and your quote should say which class you are getting.

One more thing is useful to know. MCS is moving every installer onto a redeveloped scheme, MCS: 2025, and all must be on it by 31 March 2027. Under it, the contractor standard MCS 001 is replaced by the Installer Operating Requirements and the MCS Customer Commitment, and until the move is complete the original standards remain valid. A few details, such as how quickly your certificate should arrive, depend on which version your installer is on, so ask them.

What you should get, before, during and after

This is where MCS earns its keep for a homeowner. The standards set out paperwork you are entitled to, in a set order.

Before you sign

• A performance estimate in writing. An estimated first year output, worked out by an MCS method. MCS requires it to say it is guidance only and not a guarantee, and a battery estimate must say battery benefits cannot be predicted with certainty.
• Datasheets and a layout. For the panels, the inverter and any optimisers or battery, with a drawing of where the panels go.
• Battery details. Its class, type, location, size and weight, power output and usable capacity in kWh.
• A clear contract. The make, model and power rating of the equipment and, for a battery, its storage capacity.
• A warning about other warranties. If the work could affect one, such as a roof warranty, the installer must tell you in writing and get your written permission.

During the job

The system is installed and commissioned to MIS 3002 or MIS 3012, and your installer deals with the network operator (the DNO), which by law must be told about generation or storage connected to the grid. Systems up to 16 A per phase, about 3.68 kW on a normal single phase supply, can be fitted without applying first. The DNO must be told before or at commissioning, and your installer then sends the full G98 paperwork within 28 days. Anything bigger needs approval before it is fitted, and solar and a battery count together, so adding a battery can tip a home over the limit.

After the job

You should get a handover pack with a list of key parts, safety guidance, a maintenance schedule, the manuals, all guarantees and warranties, the commissioning records and the date of the first periodic inspection. For a battery, a signed handover document also records its class, maximum power output and usable capacity.

The installation is then registered on the MCS Installation Database and your MCS certificate is issued: within 10 working days of commissioning under the original scheme’s solar and battery standards, or within 30 calendar days under the redeveloped scheme. You should also get two documents that are not from MCS at all, an Electrical Installation Certificate to BS 7671 and a Building Regulations compliance certificate, because in England a new circuit is notifiable work. Keep all three together.

Why the certificate matters for money

The Smart Export Guarantee, for solar PV

For solar PV, energy suppliers usually ask for the MCS certificate before they pay you for the electricity you send back to the grid under the Smart Export Guarantee (SEG). Ofgem’s guidance says that for solar PV up to 50 kW, both the installation and the installer must be suitably certified. MCS is the usual route, though an equivalent accredited scheme can count. Without it, a supplier does not have to pay you, although it may choose to.

You also need a meter that records exports every half hour, usually a smart meter, and an export MPAN, the reference number for your exports. Your network operator issues it once it has your installer’s commissioning paperwork. For most of Lancashire, Greater Manchester and Cumbria that is Electricity North West. In Merseyside, Cheshire and North Wales it is SP Energy Networks. Suppliers with 150,000 or more domestic customers must offer an SEG tariff, they set their own rates, and your SEG supplier need not be the company that supplies your electricity. SEG applies in England, Scotland and Wales. Our comparison of export rates shows what suppliers pay.

Batteries are not an SEG technology in their own right. Solar electricity that passes through a battery and is then exported can still count. Suppliers have to pay for it where it can be shown to be solar. Otherwise it is up to them. For SEG, it is the solar PV certificate that matters.

0% VAT does not depend on MCS

Solar panels and home batteries installed in UK homes are zero rated for VAT until 31 March 2027, after which the rate is due to go back to 5%. The relief applies when the business that installs the panels or battery also supplies them, and HMRC’s guidance sets no MCS condition. Kits bought from a shop without installation are standard rated.

When you sell

The Law Society’s TA6 property information form, which sellers fill in, asks whether you own the system outright or have leased your roof to a solar company, for the make, model and capacity of any battery, for any SEG agreement, and for a copy of the building regulations completion certificate or compliance certificate, giving MCS as an example. So keep your MCS certificate safe. It is proof the system was installed to the MCS standards, and an EPC assessor can use it as evidence of your array’s size. Keep the Building Regulations compliance certificate with it too, because without one you may not have the paperwork you need to sell.

Lost it? Ask your installer first. If they are no longer certified or trading, MCS can issue a copy to the current owner for a fee, and its helpdesk on 0333 103 8130 can check whether a certificate exists for your address. MCS cannot raise a certificate that was never issued, so make sure yours arrives.

The protection behind an MCS installation

Consumer codes. Two consumer codes for renewable installers are approved by the Chartered Trading Standards Institute: the Renewable Energy Consumer Code (RECC) and HIES. Under the redeveloped MCS scheme, every installer must follow the MCS Customer Commitment and give you a copy before you commit. Whichever applies, pressure selling is not allowed, so ask any installer which code or commitment covers your contract.

Your right to cancel. If you sign at home or at a distance, the law gives you 14 days to cancel without a reason. Where goods are supplied, the 14 days run from delivery of the last item, not from the day you sign, and if you were not told about this right the period can stretch by up to 12 months. Under RECC, work should not start in that period unless you ask for it in writing.

Deposits. Under RECC, a deposit should be a reasonable share of the price, for example 15 per cent, and never more than 25 per cent, with deposit and advance payments together capped at 60 per cent. Deposits must be insured, so that if the installer goes out of business another installer on the code can complete your contract at no extra cost. Under the redeveloped scheme, your installer must tell you how your deposit is protected.

Guarantees. Ask who backs the workmanship guarantee and check it is insurance backed, so it still stands if the installer stops trading. Under the redeveloped scheme, every installer must provide financial protection approved by MCS, with at least six years of cover, which pays for repairs if the installer goes bust, retires or refuses to fix a problem. Cover only exists if your installer registers your installation with the provider, so ask for the confirmation.

If something goes wrong

1. Complain to your installer first. MCS says 14 days is a reasonable maximum to wait for a response or an agreed plan.
2. Then go to MCS. It is the single point of contact for complaints about MCS certified installers, acknowledges within 5 working days and says most complaints should be fully resolved within 8 weeks. The MCS complaints page explains how.
3. Then independent dispute resolution. If MCS cannot settle it, eligible disputes can go to free alternative dispute resolution, paid for by MCS, within 12 months of MCS closing the complaint.

MCS cannot help if the installer was not MCS certified for that technology when the work was done, if the installation is more than six years old, or if the installer has stopped trading. In that last case, MCS will point you to any insurance backed guarantee or financial protection you can claim on. Underneath it all, the Consumer Rights Act 2015 requires any service to be carried out with reasonable care and skill.

What MCS does not do

• It does not guarantee savings. The estimate is guidance for the first year, not a promise.
• It is not a legal requirement. MCS says its certificate is not a legal requirement and is no guarantee of access to any incentive.
• It is not electrical or building control sign off. MCS is not a competent person scheme. Those certificates come from the electrician’s competent person scheme or from building control.
• It does not replace the network operator. Telling the DNO, or getting its approval, is a separate legal step.

Plug in solar shows the contrast. On 27 August 2026 it became legal in Great Britain to fit a small, solar only kit of up to 800 W yourself and plug it into a socket, as long as the kit meets the government’s plug in solar product specification. No MCS installer is involved, so there is no MCS certificate. You must tell your network operator, only one is allowed per household under the current rules, and the government’s own impact assessment expects many users will not be entitled to SEG payments. Our plug in solar guide covers the rules.

How to check any installer in five minutes

Do this before you sign, whoever you are talking to. MCS also advises getting at least three quotes.

Red flags

• Someone who says they are from MCS and tries to sell you something. MCS never cold calls and never sells warranties. Its Customer Insights team, which checks certificates with some customers, only contacts people who agreed to hear from MCS, by phone on 0333 103 8198 or by email from insights@mcscertified.com.
• Pressure to sign on the day. The Renewable Energy Consumer Code bans sales visits of more than two hours (except in recorded exceptional circumstances), an inflated first price followed by a discount for signing on the day, holding back the price until the end of the visit, unrealistic inflation or energy price forecasts and claims of limited availability.
• Savings presented as guaranteed. The MCS estimate cannot be, and says so.
• A deposit of more than 25 per cent, or no clear answer about how it is protected.
• An MCS claim that does not match the certificate, such as a certificate that does not name the technology on your quote, or talk of an “MCS certified battery”.
• Vagueness about the MCS certificate or when you will get it.

Where we stand

Energy Giants is MCS certified for solar PV and battery storage, under certificate SICI23052 MCS 1, issued by Simply Certification, a UKAS accredited certification body. The certified company is Efficient Energy Systems Ltd, which trades as Energy Giants, and the certificate covers those two technologies and nothing else. We are committed to the Renewable Energy Consumer Code, and our installations carry an insurance backed guarantee through Bluedrop. You can view and download our MCS certificate, and read what it means when we fit your solar panels or battery.

Questions people ask about MCS

Is MCS certification a legal requirement?

No. You can legally install solar panels or a battery without it. For solar PV, though, it is the usual evidence for Smart Export Guarantee payments, and MCS brings the protections described above.

Do I need an MCS certificate to be paid for exported electricity?

Usually, for solar PV. Most energy suppliers ask for the MCS certificate before paying you under the Smart Export Guarantee. Ofgem allows an equivalent accredited scheme, and a supplier may pay without one, but it does not have to.

Do I need an MCS installer to get 0% VAT?

No. The zero rate for solar panels and batteries depends on them being installed in your home, not on the installer’s certification. It runs until 31 March 2027.

How long should my MCS certificate take to arrive?

Within 10 working days of commissioning under the original scheme’s solar and battery standards, or 30 calendar days under the redeveloped scheme. If it has not arrived by then, ask your installer.

Is my battery MCS certified?

The installation can be, the battery itself cannot. MCS certifies battery installations under MIS 3012 but does not certify battery products, so what you should get is an MCS certificate for the installation.

What if my installer has stopped trading?

Claim on the insurance backed guarantee or financial protection. The provider should be named in your handover paperwork or on your MCS certificate, and most providers want defects reported within 30 days of you finding them.

About the author

Miles Sharples, Managing Director, Energy Giants

Miles has spent two decades in retrofit and has worked at scale across the UK, with long-standing relationships with local authorities including Kirklees Council, Durham County Council and Ribble Valley Borough Council. He has project-directed programmes for housing associations and delivery partners including Aspire Housing, Sureserve, LivGreen and BroadOak, and for energy suppliers including E.ON Next, Utilita, British Gas, Octopus and UKEM.

Worked with:Kirklees CouncilDurham County CouncilRibble Valley Borough CouncilAspire HousingSureserveLivGreenBroadOakE.ON NextUtilitaBritish GasOctopusUKEM

More about Miles and the teamMiles on LinkedIn