Plug-in solar in the UK: what to check before you buy

This is the most common question and the specification answers it in three places. Its scope says:

“This document applies to only plug-in solar device. It does not apply to other technologies including but not limited to … Plug-in battery systems; Plug-in solar PV devices integrated with battery systems”

And it requires the product itself to carry a warning:

“prominent warning that the plug-in solar device is not intended to be connected to, operated with, or used in conjunction with a battery energy storage system”

GOV.UK describes the scheme in the same terms: plug-in solar systems without batteries. The definition in the instrument itself also excludes a device designed to import electricity for storage; the full five-limb definition is quoted on our legal page.

• Maximum four PV modules per inverter, and maximum two in series in any string.
• 120 V DC open-circuit voltage ceiling at the inverter input. The stated reason is that the “risk of sustained DC arcing increases with DC voltage”.
• Y-connectors are not permitted.
• Combined panel power up to 2,000 W; above 960 W a professional assessment is recommended.
• Maximum apparent power is 800 VA, defined as the “highest 10-minute AVERAGE value” — a ten-minute average, not an instantaneous reading. Maximum current 3.5 A.
• IP55 at least for outdoor parts, including the outdoor socket.
• Instructions must be in English.

Mounting is where cheap kits fail. The specification is blunt:

“Mounting arrangements relying solely on cable ties, rope, string, adhesive tape, bungee cords, straps shall not be permitted.”

Any attachment method must be “reversible and non-permanent” and must not compromise the structural integrity, fire performance or weatherproofing of the building, and the manufacturer is expected to provide structural analysis covering wind and snow loading. A bundle of cable ties for the balcony railing is exactly what several budget kits ship with.

What counts as a household. The specification defines it:

“A single dwelling unit with its own electricity supply and consumer unit. In buildings containing multiple dwellings (e.g. blocks of flats, converted houses), each dwelling with its own consumer unit is treated as a separate household.”

So in a block of flats, each flat with its own consumer unit counts separately — the one-device limit is per household, not per building.

An older consumer unit needs checking. The specification says that if the installation “is using older fuse protection and does not incorporate RCBOs, the installation shall be checked and, where necessary, upgraded by a professional electrician”. Older installations using wired fuses may not protect each circuit individually.

Test the RCBO, and test it while the panel is generating. Older RCBOs “can be desensitised by products that leak DC current into the AC circuit”, so the consumer should “test the RCBO periodically by pressing the test button on the RCBO unit when the plug-in solar unit is producing power”. If it does not trip immediately, the advice is to call a competent electrician about replacing it.

Which socket. Not a lighting circuit, and not a spur serving fixed equipment such as a cooker or boiler. Two devices on sockets in the same room are not permitted if those sockets are on the same circuit. To find out what shares a circuit, switch off one breaker and see which sockets go dead together.

• Tell your network operator — twice. Notification is required both when the device is connected and when it is disconnected. The packaging is expected to carry a QR code pointing at the process.
• Label the consumer unit. A durable label near the consumer unit stating that plug-in PV is present — and a fresh label if the consumer unit is ever changed.
• Check your insurance. The specification puts this on the user: “Users are responsible for checking, before installation, whether the product may affect any relevant insurance arrangements, including their own insurance and, where applicable, insurance covering the property or building”. We have not seen this mentioned in any of the coverage.
• Permissions. The user is responsible for planning permission, listed building consent where it applies, and permission from a landlord, freeholder or managing agent — “including agreeing how any costs will be apportioned”. Our planning rules page covers the England order.

Can I use a plug-in solar device with a battery?

Not under this specification. It says in its scope that it does not apply to plug-in battery systems or to plug-in solar PV devices integrated with battery systems, and it requires the product to carry a prominent warning that the device is not intended to be connected to, operated with, or used in conjunction with a battery energy storage system. GOV.UK describes the scheme as plug-in solar systems without batteries.

How many panels can one device have?

A maximum of four PV modules per inverter, with a maximum of two in series in any string, and the open-circuit voltage at the inverter input must not exceed 120 V DC - the specification gives the reason as the risk of sustained DC arcing rising with DC voltage. Y-connectors are not permitted. The combined panel power must not exceed 2,000 W, and above 960 W a professional assessment is recommended.

I live in a flat - does one device per household mean one for the whole block?

No. The specification defines a household as a single dwelling unit with its own electricity supply and consumer unit, and states that in buildings containing multiple dwellings each dwelling with its own consumer unit is treated as a separate household. The one-device limit applies per household.

Can I fix the panel with cable ties?

No. The specification says mounting arrangements relying solely on cable ties, rope, string, adhesive tape, bungee cords or straps shall not be permitted, and requires any attachment method to be reversible and non-permanent without compromising the building. The manufacturer is expected to provide structural analysis covering wind and snow loading.

None of the above tells you whether a specific product has actually been assessed. That is what the ENA type test register is for, and the specification is explicit that being submitted is not the same as being compliant. We read that register and record every change — see the register section of our legal page.

Quoted from the Plug-in Solar Device Interim Product Specification v2.0 (July 2026), published by DESNZ on gov.uk under the Open Government Licence v3.0. Read on 23 August 2026.

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