BS EN 62109-1 and 62109-2

BS EN 62109-1 and BS EN 62109-2 work together as the principal product-safety standard for inverters used in PV systems. Part 1 provides the common requirements for PV power-conversion equipment. Part 2 supplements them for products that convert DC to AC or perform an inverter function.

This entry explains the division between the two parts. For the consumer-facing question of what a 62109 claim means on a datasheet, and which documents to obtain, see the companion inverter-safety entry.

Part 1: the general safety framework

BS EN 62109-1:2010 defines minimum requirements for the design and manufacture of PV power-conversion equipment. BSI’s published scope identifies protection against electric shock, energy, fire, mechanical and other hazards.

It applies to PV power-conversion equipment with a maximum PV source-circuit voltage no higher than 1,500 V DC. The equipment may also connect to AC mains or non-mains AC circuits no higher than 1,000 V AC and to other DC sources or loads, including batteries.

Those values define the technical scope of the 2010 edition. They are not recommended domestic operating voltages. The ratings permitted for a particular inverter are the lower limits stated by its manufacturer, and the installation design has to remain within them.

The general framework covers matters such as protection from accessible hazardous parts, insulation, protective bonding, abnormal operating conditions, temperature and fire risk, mechanical construction, markings and instructions. The precise test conditions and pass criteria are in the standard and should not be reconstructed from a simplified checklist.

Part 2: requirements particular to inverters

BS EN 62109-2:2011 applies the Part 1 framework to DC-to-AC inverters and to products that include an inverter function. IEC states explicitly that it must be used jointly with Part 1.

Its scope includes:

grid-interactive inverters
stand-alone inverters
multiple-mode inverters
products supplied by one or more PV arrays
inverters intended for use with batteries or other forms of energy storage

That makes the pair relevant to many hybrid inverters. It does not mean that every product described as a battery inverter automatically falls within the PV-specific scope, or that 62109 covers the battery itself. The manufacturer’s declaration must identify the standards actually applied to the particular product.

Part 2 deals with inverter-specific safety matters while retaining the Part 1 requirements. It does not set the national grid-connection rules for a generating plant. IEC’s published scope separates the product-safety assessment from grid interconnection requirements.

A hierarchy, not interchangeable certificates

The same installation usually needs several distinct layers of evidence:

Layer	Principal question
BS EN 62109-1 and -2	Is the inverter designed as a safe product for its declared use?
G98 or G99, with G100 where relevant	May this model and scheme operate in parallel with the distribution network?
BS 7671	Is the fixed electrical installation correctly designed, erected and verified?
Battery product and system standards	Are the cells, battery and assembled storage system appropriately assessed?
PAS 63100	Does the domestic battery installation address its fire-safety requirements?

Passing one layer cannot compensate for missing evidence at another. In particular, a G98 or G99 listing is not an electrical product-safety certificate, and a 62109 declaration is not grid-connection approval.

Part 3 is a different application

IEC 62109-3:2020 contains particular safety requirements for electronic devices mechanically or electrically incorporated with PV elements. IEC describes these combinations as module-integrated equipment.

Part 3 is therefore relevant to the particular integrated product it covers. Its existence does not turn a conventional string inverter’s Part 1 and Part 2 evidence into a three-part requirement. The product documentation should identify the parts that match the product architecture.

Testing and conformity evidence

The standards contain construction requirements, inspection requirements and tests for representative equipment. The conformity route used for a product determines what laboratory and certification evidence exists behind the manufacturer’s declaration.

It is inaccurate to assume that every CE- or UKCA-marked inverter has been independently approved by government or that third-party certification is always mandatory. The responsible manufacturer must carry out the applicable conformity assessment and maintain the technical evidence. A competent test laboratory or certification body may perform some or all of the assessment, but the manufacturer’s legal responsibilities remain.

When reviewing a product family, confirm that the evidence covers the exact model and relevant variants. A report for a related enclosure or different power rating does not automatically cover the unit being supplied.

Current status

As at 22 July 2026, BSI lists both BS EN 62109-1:2010 and BS EN 62109-2:2011 as current, designated and under review. Part 1 is identical to EN 62109-1:2010 and IEC 62109-1:2010; Part 2 is identical to EN 62109-2:2011 and IEC 62109-2:2011.

Because both are under review, future editions may change the detail. A specification, declaration or procurement record should always include the edition year. Draft revisions and project timetables are deliberately not reproduced here because they can change before publication and do not replace the current standards.

BS EN 62109 inverter safety standard
BS EN 50549 grid connection standards
G98 and G99 grid connection
BS 7671 IET Wiring Regulations
UKCA and CE marking
Hybrid inverters