BS EN 62109 inverter safety standard

BS EN 62109 is a product-safety standard for power converters used in PV systems. On a solar, hybrid or compatible battery-inverter datasheet, it is evidence about the design of the inverter itself. It is not approval for the whole installation and it is not permission to connect the inverter to the electricity network.

The useful question is not simply whether a brochure displays “62109”. It is whether the manufacturer has declared the exact model against the relevant parts and editions, and whether the other approvals needed for the proposed use are also in place.

What the number should look like

For an ordinary PV inverter, the declaration will normally refer to both:

• BS EN 62109-1:2010, which contains the general safety requirements for PV power-conversion equipment
• BS EN 62109-2:2011, which adds the particular requirements for inverters

Part 2 has to be used with Part 1. A vague claim such as “IEC compliant” or a reference to Part 2 alone deserves clarification.

The prefixes describe adoption of the same technical text. IEC 62109 is the international standard; EN 62109 is its European adoption; and BS EN 62109 is the British adoption. A manufacturer’s documentation may therefore use IEC, EN or BS EN depending on the market and certification route. The edition year still matters.

As at 22 July 2026, BSI lists BS EN 62109-1:2010 and BS EN 62109-2:2011 as current and under review. “Under review” does not mean that either standard has ceased to apply. It means a future revision is possible, so the compliance record should retain the edition year rather than giving only the base number.

What it covers

Part 1 sets minimum design and manufacturing requirements intended to protect against electric shock, energy, fire, mechanical and other hazards. Its scope includes PV power-conversion equipment connected to other DC sources or loads such as batteries.

Part 2 covers DC-to-AC inverters and products that perform an inverter function in a PV system. The IEC scope includes grid-interactive, stand-alone and multiple-mode inverters, including products intended for use with batteries or other energy storage.

Together, the two parts address the safety of the product as supplied. They do not rate its efficiency, reliability, software quality, customer support or expected life.

What it does not prove

A 62109 declaration does not establish that:

• the model meets G98 or G99 requirements for connection to a Great Britain distribution network
• its export-limitation function has the evidence required for a G100 scheme
• the cables, protection, earthing, isolation and mounting of the particular installation comply with BS 7671
• the battery cells, modules or complete battery system meet their own applicable standards
• the product is eligible for an MCS-certified installation
• the quoted model, firmware and hardware revision match the version covered by the evidence

These are separate questions. An inverter can be safe as a product yet unsuitable for the proposed grid connection or poorly installed.

How it relates to CE and UKCA marking

In Great Britain, the Electrical Equipment (Safety) Regulations 2016 apply to equipment within their stated voltage range. They require the manufacturer to meet the safety objectives, complete the applicable conformity assessment, prepare technical documentation and issue a declaration of conformity before applying the relevant conformity marking.

BSI identifies Parts 1 and 2 as designated standards. Use of a designated standard can give a rebuttable presumption of conformity with the legal requirements it covers. The standard remains voluntary, however, and the manufacturer remains responsible for the product. A standard is not legislation and a conformity mark is not a government approval of each individual inverter.

As at 22 July 2026, Great Britain permits relevant electrical equipment to use either CE or UKCA marking, provided the conditions of the chosen route are met. Northern Ireland follows a different market-access regime. The marking position is covered in detail in the separate UKCA and CE entry.

Evidence worth checking

For a specified inverter, obtain the manufacturer’s declaration of conformity and check:

• the manufacturer’s legal name and address
• the exact model or product-family identifier
• the standards and edition years listed
• whether both Part 1 and Part 2 appear where applicable
• the declaration date and the person signing for the manufacturer
• whether the model offered is the model described in the declaration

A laboratory certificate or test report can add confidence, particularly for an unfamiliar brand, but the law does not make a third-party certificate the universal substitute for the manufacturer’s responsibilities. A cropped certificate image or an undated brochure claim is weaker evidence than a traceable declaration tied to the product.

Then check the separate grid-connection record, installation design and battery evidence. No single certificate covers all of them.

Related entries

• BS EN 62109-1 and 62109-2
• BS EN 50549 grid connection standards
• G98 and G99 grid connection
• BS 7671 IET Wiring Regulations
• UKCA and CE marking
• Hybrid inverters