Is MCS certification required for a farm solar install?

“Is the installer MCS certified?” is the first question most farms ask, and for a barn-roof array it is often the wrong one. This post sets out what MCS actually covers, where the 3.68 kW figure that appears in so many installer pages comes from, and which registers to check for a farm install of any size. It is the research behind the checking guide to agricultural solar panel installers.

What MCS is

The Microgeneration Certification Scheme describes itself as the UK’s quality mark for small-scale renewables. It certifies installation companies and products — solar PV, heat pumps, biomass, small wind and others — against its standards, and it publishes an installer search you can filter by postcode and technology. It is a certification scheme, not a licence: nobody is prohibited from installing solar without it.

Where it bites is the Smart Export Guarantee. Ofgem’s scheme requires eligible installations to meet the certification criteria, and for solar PV that means MCS (or an equivalent scheme) for installations up to 50 kW. For a farm workshop array, a small equestrian yard or a single-shed system under that line, MCS therefore matters if you want to be paid for export, and the installer search is the place to check the company.

Where MCS stops

Many farm-building arrays are larger than 50 kW. A 100 kW grain-store roof or a 250 kW multi-shed livestock site is above the scale MCS was designed for, and there is no MCS requirement on them. That is not a loophole; it simply means the assurance comes from elsewhere:

• The electrical registration. The contractor certifying the wiring under BS 7671 should be on the NICEIC, NAPIT or ELECSA register. This is the registration that covers the AC side, the isolation and the certificate you are handed at commissioning.
• The G99 acceptance. Above 3.68 kW per phase the distribution network operator must approve a G99 application before the system is energised. The acceptance letter, with any export limit, is the single most important document on a farm project.
• The equipment listing. Inverters and generation equipment for G98 and G99 connection are type-tested and listed on the ENA type-test register. If the inverter in the quote is not on it, the application stalls.
• References and Companies House. Two named farm references in your building type, and a filing history that matches the trading name on the quote.

An installer that leads with “MCS certified” on a 200 kW livestock project is not lying, but they are answering a question you did not need to ask. Ask about the G99 instead.

Where 3.68 kW comes from

The figure is the G98 limit: 16 amps per phase, which is 3.68 kW on a single phase (11.04 kW across three). Up to that size an installer can connect under G98 and notify the network operator afterwards; above it a G99 application must be approved first. It has nothing to do with certification. Pages that say “above 3.68 kW you need MCS commercial certification” have welded a network threshold to a scheme that does not have a commercial tier, and it is a reliable sign that the page was written from other pages rather than from the source.

The check that costs nothing

For any farm array:

1. If it is 50 kW or under and you want the SEG, find the company on the MCS installer search for solar PV.
2. Whatever the size, find the electrical contractor on the NICEIC or NAPIT register.
3. Ask which DNO the G99 goes to, who submits it, and what happens if it comes back with an export limit.
4. Look up the proposed inverter on the ENA type-test register.
5. Look up the company on Companies House and call two farm references.

Ten minutes, all public, and it tells you more than any accreditation logo on a homepage. The full list of questions is in the 30-question installer checklist, and the rules the installer should be applying to your building are on solar panels for agricultural buildings.

Batteries and “MCS approved”

One more claim to test: “our batteries are MCS approved”. Check the specific product on the register the quote names rather than taking the phrase at face value, and for anything that connects to the grid — inverters, export limiters — the listing that matters for the connection is the ENA type-test register. The installer who can show you the listing is the one to keep talking to.