The product specification
The document the legislation points at. It defines what a compliant device may be, and it is where most of the numbers people quote actually come from.
3.1Power and quantity limits
| Parameter | Limit |
|---|---|
| Maximum apparent power | 800 VA |
| Rated voltage | Up to 253 V AC |
| Rated frequency | 50 Hz |
| Devices per final ring circuit | One |
| PV modules per inverter | Up to four |
| Modules in series per string | No more than two |
The specification permits one device per final ring circuit. It then records that Great Britain network connection requirements also apply, and that G98 Issue 2 Amendment 1 2026 restricts this to one device per household, which applies unless and until that is amended. One per household is the operative figure.
3.2Device classification
| Type | Composition | DC connections |
|---|---|---|
| One-component | A single PV module with an integrated inverter | Already made |
| Two-component | A PV module and an inverter, supplied as a kit | Made by the user |
| Multi-component | One or more modules and an inverter | Made by the user |
3.3Mounting position
The inverter and the BS 1363 plug and socket outlet may be mounted internal or external to the premises. Where they are external, the socket outlet must have an ingress protection rating of IP55 or better.
Where the installation requires DC cables to be routed from an outdoor location into the premises, the manufacturer must supply the appropriate DC connectors and clear instructions on the permitted method of routing and installation.
3.4Residual current and fire
Plug-in solar must comply with the requirements relating to DC residual current components in accordance with BS EN 62109-1 Clause 7.3.8. The device must not adversely affect the operation of upstream residual current devices, and smooth DC residual current to the mains must not exceed 5 mA under normal operation and relevant fault conditions, demonstrated by testing at maximum apparent power output.
Fire risk must be considered at system level, including the module, the mounting system and the surface it is installed on.
3.5Exclusions
The specification applies only to plug-in solar devices. It expressly does not apply to:
PV systems under BS 7671 Section 712 |
| Building-integrated PV |
| Plug-in battery systems |
| Plug-in solar PV devices integrated with battery systems |
| Plug-in generation from sources other than solar PV |
This is the exclusion most likely to be misrepresented at the point of sale. Respondents to the consultation argued that excluding batteries reduced consumer payback. The exclusion was retained.
3.6Who may install, and the boundary
The specification governs devices intended for installation and operation by ordinary persons. No electrician, competent person scheme or certificate is required to connect a compliant device to a sound existing socket.
The boundary is the building's installation. Manufacturer instructions must state that any necessary testing or modification of the installation is to be performed only by professional electricians in accordance with the distribution code, G98 and BS 7671. Where connection requires modification of the final circuit, for example replacing the overcurrent protection device under BS 7671 Section 551.7.2, the instructions must identify that as work only a qualified electrician may perform.
Users must additionally be advised not to connect the device to damaged, degraded or non-compliant socket outlets, to seek inspection by a qualified electrician where the condition or suitability of the installation is in doubt, and to check whether the product affects any relevant insurance arrangements.