Are plug-in solar panels safe? What the UK specification requires
The safety worry is a live plug and a shock. The government specification answers it with numbers: disconnect within 100 milliseconds, under 34 volts at the pins, and a hard limit on panel voltage. Here is what each means.
Rules and product details last checked on .
Key takeaways
- The main hazard is a live plug, and the specification designs it out. On losing the grid, the inverter must disconnect within 100 milliseconds and the voltage at the plug pins must fall below 34 V within the same time.
- Panel voltage is capped. Open-circuit voltage at the inverter’s inputs may not exceed 120 V, and no more than two panels may be wired in series.
- Current is capped too: 3.5 A into your home, 800 VA of apparent power.
- This only holds for a certified device. An uncertified marketplace inverter may do none of it, which is where the real risk sits.
- Two things remain your job: plug it into a socket circuit, and mount it so it cannot fall.
The honest answer to “are they safe” is “the certified ones are built to a written standard, and the standard is checkable”. Here is what it says.
The shock question
Pull the plug out of a live socket and the pins would be live if the kit kept pushing power. It does not. A plug-in inverter is grid-following: it follows the waveform already on your wiring, so when the grid disappears there is nothing to follow and it must stop.
The government’s Plug-in Solar Device Interim Product Specification, version 2.0 (clause 6.2.3.3) sets two clocks. The inverter “shall automatically disconnect from the mains supply within 100 ms”. And “the voltage at accessible plug pins shall decrease to below 34 V within 100 ms”, with any large capacitor falling below 34 V within one second. We unpack both in our microinverter guide.
This is why a compliant kit unplugged in bright sun has dead pins within a tenth of a second even though the panels are still generating. Do not test that on your own kit; rely on the certification.
The DC side
The panels themselves make direct current, which is harder to interrupt than alternating current. The specification limits it: open-circuit voltage at the inverter inputs must not exceed 120 V, and no more than two panels may be wired in series in any string, because series panels “can produce harmful DC voltages at the inverter input leading to an electrocution risk and the possibility of DC arcing”. An unused AC output, provided for adding a second inverter, must be closed with a cap removable only with a tool.
The wiring in your home
The kit feeds your home’s wiring through a socket, so the specification limits what it can push in: 800 VA of apparent power and 3.5 A of current, the inverter controlling itself to stay inside that. 3.5 A is a fifth of the 16 A ceiling below which the notification rules apply the simple route. The specification also says a kit may be connected only to a socket circuit, never to one feeding lighting or fixed equipment.
Where the real risk is
An uncertified inverter. Everything above is what a compliant device is tested to. A cheap marketplace inverter with no working anti-islanding will happily back-feed a dead grid. The words to look for are not “safe” or “CE” on a listing but the standards the specification names: BS EN IEC 62109-1 and -2 for safety and BS EN 62116 for islanding prevention, plus an entry in the type-test register. When we surveyed sellers, most did not publish one, so ask.
How you mount it. Nothing in the specification stops a badly fixed panel from falling off a balcony. Fix it as the maker instructs, and see where you can and cannot put it.
What we have verified, and what we have not
Verified against the primary source, checked 23 August 2026. The 100 ms disconnection and 34 V discharge requirements, the 120 V and two-panel limits, the 800 VA and 3.5 A limits, the socket-circuit restriction, and the standards named, all quoted from specification version 2.0.
Not verified. That any specific product on sale meets them. We have not tested hardware or seen a certificate. A specification says what a device must do, not that a given box does it.
Our editorial policy explains how we handle claims we cannot check.
This page carries the date it was last checked. If the specification is revised, tell us and we will verify it and update the date.