Inverter & power-converter safety for V2X — why a CE / 62109 mark is not anti-islanding proof
BS EN 62109 is the product-safety standard for the power-electronics in PV, battery and EV-derived systems — Part 1 the general safety floor, Part 2 the inverter specifics (including stand-alone and battery-fed units). It is the standard you will see on a bidirectional charger or V2L unit's type-plate. The critical limit: a 62109 (or CE) mark proves the converter is a safe product — it does not prove the inverter will safely disconnect from a dead grid. Anti-islanding lives in ENA G98/G99 and BS 7671, with islanding test methods in IEC 62116.
In short
- BS EN 62109-1 is the general converter safety floor; -2 adds inverter specifics, incl. stand-alone and battery-fed units.
- It is the standard most likely cited on a bidirectional charger / V2L unit's type-plate.
- A 62109 (or CE) mark is NOT evidence of anti-islanding compliance — do not treat it as such.
- Anti-islanding and grid protection live in ENA G98/G99 and BS 7671, with islanding test methods in IEC 62116.
- Part 1 Edition 2 is in draft (target Oct 2026), not yet published — cite the 2010 edition as current.
Where this stops: This explains what an inverter's safety mark does and does not prove. Anti-islanding and grid protection are competent-person and DNO matters, not a product-mark claim.
Some details below depend on sources still being verified against the published standard, so we mark them Not confirmed rather than guess:
- BS EN 62109-1 Edition 2 is in draft (target Oct 2026) — not yet published; cite the 2010 edition as current until it is.
What the standard does prove
BS EN 62109 is the product-safety series for power converters in PV — and, by extension, battery and EV-derived inverters that share the same DC-to-AC architecture. Part 1 sets the general safety baseline (shock, energy, fire, mechanical, thermal); Part 2 adds inverter specifics and explicitly contemplates stand-alone and battery-fed inverters. So a 62109 mark tells you the conversion hardware was designed to a recognised safety baseline.
What it does NOT prove
A CE / 62109 mark is not anti-islanding proof
Part 2 covers the inverter as a product but does not set grid-interconnection or anti-islanding performance. Do not present a 62109 (or CE) mark as evidence that a V2X inverter will safely disconnect from a dead grid.
What the diagram shows: Two arrangements. On the left, the grid and the EV/source are connected together (in parallel) — this engages ENA Engineering Recommendations G98/G99, so the DNO must be notified. On the right, a break-before-make changeover switch connects the load to either the grid OR the EV/source, never both together (islanded) — a source that can never run in parallel or export is generally treated as a load and sits outside G98/G99. Whether a given changeover genuinely prevents parallel operation is a design-and-test matter for the competent person and the DNO. The exact G98/G99 clause locators are Not confirmed pending the official PDFs. Legend (stated in words, not colour alone): L = line/live conductor; N = neutral; E/CPC = earth / circuit protective conductor.
For a UK backup install, the disconnection/transfer-switching and grid-protection duty is governed by ENA G98/G99 and the BS 7671 wiring rules, with islanding test methods in IEC 62116. For a true islanded V2L (changeover, never grid-parallel), the safety comes from the changeover and earthing, not from a grid-interactive anti-islanding function.
One more boundary: BS EN IEC 62909-1 (bidirectional grid-connected converters) explicitly excludes PV and EV/charging-station bidirectional converters, so it does not govern the EV-side converter in a V2L/V2H install — don't cite it as applicable.
How this is made and proven compliant
- BS EN 62109-1 / -2 (converter/inverter product safety)
- ENA G98/G99 + BS 7671 for grid protection and anti-islanding; IEC 62116 for islanding test methods
A competent person verifies the installation's protection and (where grid-parallel) the DNO agrees the connection. The product mark alone does not discharge these duties.
- Confirm the converter declares to BS EN 62109-1/-2
- Separately verify anti-islanding / disconnection per ENA G98/G99 + BS 7671 (not via the 62109 mark)
- Where islanding behaviour is claimed, look to IEC 62116 test methods
Confidence: Inference rolled up across the clauses cited above (the strictest state wins).
Frequently asked questions
My inverter is CE-marked and 62109-compliant — is it safe to island?
Those marks prove product safety, not anti-islanding behaviour. Whether a system safely disconnects from a dead grid is governed by ENA G98/G99 and BS 7671 (with IEC 62116 test methods), verified by a competent person — not by the 62109 mark.
Does a V2L socket need anti-islanding at all?
A pure islanded V2L feed (changeover, never grid-parallel) is not synchronised to the grid, so the safety comes from the break-before-make changeover and the earthing — not from a grid-interactive anti-islanding function. Grid-parallel V2G is the case that engages G98/G99.
Which 62109 edition is current?
Cite the 2010 edition of Part 1 as current; a Part 1 Edition 2 is in draft (target Oct 2026) but not yet published.
- Last reviewed
- 14 June 2026
- Written against
- BS 7671:2018 + A4:2026
- Reviewed by
- Martin (qualified UK electrician)
- Next review due
- 14 December 2026
General information, not project-specific design advice. Standards are cited by reference only and never reproduced. How we source this.
References & sources (2)
- BS EN 62109-2 (inverters) — BSI — cited by reference only
- ENA EREC G98 / G99 (grid protection) — Energy Networks Association — anti-islanding lives here, not in 62109