MCS 042: UK Battery Product Standard Proposals and Nov 10 Deadline
What MCS Is Consulting On
MCS, the UK's certification body for small-scale renewables, opened a four-week consultation on October 13, 2026 on a new Battery Storage Product Standard, MCS 042. The draft was written by MCS's Battery Storage Technical Working Group, which includes installers, manufacturers, trade associations and certification bodies. Comments close at 11:59 pm on Tuesday, November 10, 2026.
Responses go to consultations@mcscertified.com using the consultation form that MCS publishes alongside the draft. After the deadline, MCS will review the feedback, finalise the standard with the working group and publish it. MCS describes this as the first step toward bringing the standard into the scheme.
Why a Product Standard Now
Battery storage is the fastest growing technology in MCS. More than 60,000 batteries were installed in UK homes and small businesses through the scheme in 2026 by the end of September, which is already over 50% more than the record total for all of last year.
The scheme has an installation standard for batteries, MIS 3012, which covers systems up to 50 kW. It does not have a product standard, so there is no MCS-defined test regime for the battery itself. Solar panels do. Their product standard requires testing against standards such as IEC 61215 and IEC 61730, factory production control, proof that production units match the tested sample, and ongoing surveillance.
MCS's technical manager for electric, Ted Woodward, told ESS News that the market has matured enough to justify a dedicated product standard, and that for buyers it would mean third-party verified information on the battery they are paying for.
What the Draft Proposes
MCS's draft is a Word document, and the details below come from ESS News's reading of it. Treat them as proposals.
Area | Proposed requirement (as reported) |
|---|---|
Cell and pack safety | IEC 62619:2022 for secondary lithium cells and batteries in industrial applications, and UN 38.3 for transport |
Power electronics | BS EN 62477-1 for integrated battery and inverter systems |
Electromagnetic compatibility | IEC 61000 |
Wireless products | BS EN 18031, which would apply only to products with wifi, Bluetooth or another radio interface |
Cybersecurity | ETSI EN 303 645 baseline: no default passwords, secure software updates, vulnerability handling and secure communication between battery, inverter and any app or cloud platform |
Performance data | Declared nominal energy capacity, input power, output power, round-trip efficiency and expected service life, plus usable capacity where it is lower than nominal |
Factory controls | A regime similar to solar panels, including factory production control and ongoing surveillance, possibly with factory inspections |
What Would Be Covered
The standard would apply to AC-coupled systems where the battery packs and inverter sit in one enclosure or in close-coupled enclosures. It would also cover DC-coupled battery packs, with or without an integrated battery management system. Reports describe it as covering both the residential and commercial and industrial segments.
What the Industry Says
The Energy Storage Association sits on the working group and supports the idea. It told ESS News that many battery products already go through factory testing and third-party audits, for example by TÜV, and that it sees the MCS standard as locally trusted validation of products already held to those standards, not as an extra UK-only burden. The final shape has not been agreed.
What Happens Next
- October 13, 2026: consultation opens.
- November 10, 2026: consultation closes.
- After that: MCS reviews responses, finalises the standard with its working group and publishes it.
- Implementation: MCS says it cannot confirm a timeline. There will be a transition period for certified installers until an adequate number of MCS-certified battery products are on the market.
What This Means for Installers and EPCs
- Nothing changes today. The consultation is on a draft, and MCS says installers will have time to adjust.
- Ask suppliers now. Check whether the batteries you install already hold IEC 62619 and UN 38.3 evidence and a cybersecurity statement, and keep them with the product records.
- Quote the usable figure. The draft's focus on usable capacity versus nominal capacity matches a question customers already ask, so quotes that show both will age well.
- Consider responding. Installers and EPCs can respond by email before the deadline, and MCS says it welcomes input from installers, manufacturers and trade associations.
- Check the final text. Which products fall in scope, and when installers must switch, will depend on the standard MCS publishes. Our guide to the MCS 2027 deadline covers the separate changes to the installer scheme.
Where Design Software Fits
A battery quote is easier to defend when the product records sit alongside the design. Design software like Reslink produces the bill of materials and proposal documents from one design, so the equipment list and the quote match. It does not certify products or check them against MCS.
See the full workflow → Book a demo
Frequently Asked Questions
Q1. What is MCS 042?
A draft product standard for battery storage from MCS. It would set testing, safety, cybersecurity and performance data requirements for batteries used in MCS-certified installations.
Q2. When does the consultation close?
At 11:59 pm on Tuesday, November 10, 2026.
Q3. How do I respond?
Email consultations@mcscertified.com with the consultation response form from MCS's website.
Q4. Does it apply now?
No. It is a draft. MCS will review responses, finalise the standard and publish it, and has not given an implementation date.
Q5. Which batteries would it cover?
AC-coupled systems with the battery and inverter in one or close-coupled enclosures, and DC-coupled battery packs with or without a battery management system, for homes and commercial sites.
Q6. What tests are proposed?
According to ESS News, IEC 62619:2022 and UN 38.3 for safety, BS EN 62477-1 and IEC 61000 for integrated systems, and a cybersecurity baseline from ETSI EN 303 645.
Q7. Will installers have to stop using current batteries?
MCS says there will be a transition period until enough certified products are available. Which batteries qualify will depend on the final standard.
Final takeaway
MCS 042 would give batteries the same kind of product certification that solar panels already have. For installers and EPCs, the next six days matter for anyone who wants to comment, and the longer-term step is to start asking manufacturers for the test evidence and usable capacity data the standard is likely to require.
You May Also Like
- MCS 2027 Deadline: What's Actually Changing for Solar and Battery EPCs
- BS 7671 Amendment 4: What Solar and Battery EPCs Must Do
- NFCC BESS Guidance 2026: What's Confirmed and What's Open for UK EPCs
Sources
- MCS, MCS launches four-week consultation on new Battery Storage Product Standard (October 13, 2026)
- MCS, Consultations (live consultation listing, November 2026)
- ESS News, UK battery product standard in development for small-scale installations (October 30, 2026)
This guide reflects MCS's announcement and published reports of the draft standard as of November 4, 2026. MCS may change the draft after the consultation, so check MCS's website for the final text and dates.
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