Interim Product Specification v2: What It Means for Kits

DESNZ published the Interim Product Specification v2 on 16 July 2026. We break down the technical requirements every kit must meet.

What Is the Interim Product Specification?

The Interim Product Specification v2 (IPS v2) is a technical document published by DESNZ on 16 July 2026 that sets out exactly what a plug-in solar kit must do to be sold legally in the UK.

It's not a British Standard — BSI will publish a full product standard later — but it has the force of law because SI 2026 No. 848 requires all plug-in microgenerators to comply with it.

The Key Technical Requirements

Power Output Limits

Maximum AC output: 800VA / 3.5A
Maximum DC panel input: 2000W
The 3.5A limit ensures the system stays well within the 5A fuse rating

Plug and Fuse

Must use a BS 1363 plug (standard UK 3-pin)
Fitted with a 5A fuse (not the standard 13A)
The plug must be part of the certified system — you can't use an extension lead

No Battery Storage

Batteries are not permitted in the plug circuit. This means:

The inverter cannot include integrated battery storage that feeds through the plug
Separate battery systems connected on the DC side (before the inverter) may be permitted in future revisions
This is a safety decision — batteries add fire risk and complicate anti-islanding

Safety Features

Anti-islanding protection: The system must disconnect within 5 seconds if mains power fails
Automatic reconnection delay: Must wait at least 60 seconds after mains power returns before reconnecting
Earth fault protection: Built-in residual current detection
Over-voltage protection: Must disconnect if voltage exceeds limits
Frequency monitoring: Must disconnect if grid frequency drifts outside 47–52Hz

One Per Household

Only one plug-in microgenerator is permitted per domestic premises. This is a key difference from Germany, where the limit is per-socket-circuit.

What This Means for Manufacturers

Manufacturers must:

Submit their complete kit for testing against the IPS v2
Obtain certification from an approved testing body
Mark compliant products with the required safety certifications
Include clear installation instructions that meet IPS v2 requirements

EcoFlow is expected to be the first manufacturer to achieve certification, with the STREAM kit launching in September 2026.

What This Means for Buyers

When shopping for a plug-in solar kit, look for:

IPS v2 compliance marking on the packaging
5A fuse in the plug (not 13A)
No battery in the inverter/plug assembly
Complete kit: panels, inverter, cabling, and plug sold as one certified system

Don't buy a microinverter and panels separately and assume they're legal — the IPS v2 requires the entire system to be certified as a unit.

How Does IPS v2 Compare to European Standards?

Germany's VDE-AR-N 4105 allows up to 800W via a Schuko plug. The UK's IPS v2 is broadly similar in output limits but differs in requiring a BS 1363 plug with a 5A fuse and prohibiting batteries. The UK specification is more conservative — particularly on batteries — reflecting a cautious first step.

What Comes Next?

BSI is developing a full British Standard for plug-in solar devices. When published (expected 2027), it will replace the interim spec and potentially relax some restrictions — particularly around battery storage and the one-per-household limit.

Will the 800W limit increase?

Not in the near term. The 800W limit is embedded in both BS 7671 Amendment 4 and the IPS v2. Any increase would require further amendments to both the wiring regulations and the product specification.

Can I add a battery to my plug-in solar system?

Not through the plug circuit. You could theoretically use a separate battery system that charges from the panels and discharges through a different circuit, but this falls outside the scope of the IPS v2 and may require a qualified electrician.

What about multiple plug-in solar kits?

The IPS v2 limits you to one plug-in microgenerator per household. Multiple units on one circuit are not permitted under the current specification.