The Interim Product Specification covers connection to an existing home installation “without requiring installation of a separate electrical circuit for export”. What it does set are rules on the socket, the circuit and your protection.
- max plug fuse
- 5 A
- min outdoor socket rating
- IP55
- panels above which to consider an assessment
- 960 W
Which socket can you use?
The specification and the Explanatory Memorandum require:
- A fixed BS 1363-2 socket. That’s a normal wall socket, single or double.
- A plug that goes straight in. No extension leads, multi-way adaptors, travel adaptors or plug-in RCD adaptors.
- A socket circuit. Not a lighting circuit, and not a spur that feeds fixed equipment such as a cooker or boiler.
- Outdoor sockets rated at least IP55. Outdoor kit components must meet IP55 too.
The kit’s own plug is a moulded, non-rewireable BS 1363-1 plug with a fuse of no more than 5 A. Don’t cut it off or swap it.
No socket where the panels go? Don't use an extension lead
An extension lead isn’t allowed, even an outdoor one. Use the kit’s own cable and a socket within reach. Adding a new socket, for example on a balcony, is electrical installation work that the plug-in rules don’t cover, so talk to a registered electrician.
Do you need an RCD or RCBO?
An RCD cuts the power if current leaks to earth. An RCBO combines an RCD with a circuit breaker for a single circuit.
What the specification says
- Check your installation has modern residual current protection (RCBO).
- Homes with older fuses and no RCBOs should be checked and upgraded by an electrician.
- Kits must keep their DC residual current to 5 mA or less.
- Test the RCBO periodically while the kit is generating.
What Electrical Safety First recommends
Electrical Safety First goes further. It recommends “at least a Type A bidirectional RCD” on circuits used for plug-in solar. It says homes with Type AC RCDs “should not use plug-in solar systems without first upgrading”. That’s their recommendation, not a legal requirement, but worth asking your electrician about.
If you’re not sure what protection your circuits have, ask a registered electrician. Don’t open the consumer unit yourself.
What we couldn't confirm
The specification says circuits with MCBs protected by an upstream RCD “may also be acceptable, subject to verification through further testing now being undertaken by DESNZ”. We haven’t seen the results, so if that’s your setup, ask an electrician.
Do you need an electrician?
Not always. The official guidance points to one when:
| Situation | Source |
|---|---|
| Older fuses and no RCBOs | IPS §8.3.2 |
| Kit has more than 960 W of panels (“consider professional assessment”) | IPS §4.1 |
| The circuit needs changing, e.g. replacing its overcurrent protective device | IPS §8.3.2 (qualified electrician only) |
The IET and Electrical Safety First both recommend a check before you buy, even if none of these apply.
Other wiring rules
- One device per household. Under G98 you can’t run a second plug-in kit on another circuit. The specification would allow one per circuit, but G98 takes precedence until it’s amended (Government Response).
- Label your consumer unit. Kits include a warning label to fix near it.
- Existing rooftop solar. A plug-in kit can coexist with it if the total stays within 16 A per phase (Ofgem). Ask an electrician if you’re unsure.
- Panel side. Up to 4 panels, no more than 2 in series, no Y-connectors. Connect panels only as the kit’s instructions show.
Can you plug any solar panel into a socket?
No. Only a complete kit listed as Compliant on the ENA Type Test Register and meeting the specification is legal. A standalone inverter or a panel with a DIY plug isn’t. See the compliance checklist.
What to do next
- Check a kit suits your home with the compatibility checker.
- For how the wiring regulations fit in, see BS 7671 and plug-in solar.
