Solar inverter certifications: UL 1741, IEC 61683, IEC 62109

This article describes the main certifications for solar inverters. There are several certifications that apply to solar inverters, including EN 50524, EN 50530, UL 1741, IEC 61683, IEC 62109-1, and IEC 62109-2.

Before going into more detail, let’s briefly discuss the main certification bodies that design and safeguard these certification standards for solar inverters.

What are the International Certification Bodies?

Leading national and international organizations, involved in the development of solar power generating systems, create certification standards that dictate the safety requirements and often durability requirements of fuses used in solar systems. While some standards are mandatory (violators may be prosecuted as per law), others are just for elevating the product standard and to include industry best practices and benchmarks. Leading organizations involved in developing standards, in the field of solar power are:

• IEC: International Electro-technical Commission
• UL: Underwriter Laboratories Inc.
• IEEE: Institute of Electrical and Electronics Engineers
• CEN: European Committee for Standardization

Leading standards focussing on inverters for solar power systems

The quality of a solar inverter is important as it’s usually the first component in a solar power system that might need replacement. Besides durability, the solar inverter’s efficiency while converting the electricity produced by the solar panel (DC) to electricity consumed by the loads (AC) is important, as it directly influences the solar system’s performance. The following standards list requirements for solar inverters such as the desired nameplate information, requirements for the safe operation of inverters, procedures for measuring efficiency, the general standard for inverters connected in independent power systems, and many other requirements.

1. EN 50524 (Data Sheet and Name Plate for Photovoltaic Inverters)
2. EN 50530 (Overall Efficiency of Photovoltaic Inverters)
3. UL 1741 (Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources)
4. IEC 61683 (Power conditioners – Procedure for measuring efficiency)
5. IEC 62109-1 (Safety of Power Converters for Use in Photovoltaic Power Systems – Part 1: General Requirements)
6. IEC 62109-2 (Safety of Power Converters for Use in Photovoltaic Power Systems – Part 2: Particular Requirements for Inverters)

Certification standard overview

EN 50524 (Data Sheet and Name Plate for Photovoltaic Inverters), Key Points[1]:

• This European Standard describes datasheet and nameplate information for photovoltaic inverters in grid parallel operation.
• The intent of this document is to provide the minimum information required to configure a safe and optimal system with photovoltaic inverters.
• Datasheet information is a technical description that is a sign of durable construction at or in the photovoltaic inverter.

EN 50530 (Overall Efficiency of Photovoltaic Inverters), Key points: [2]:

• This European Standard provides a procedure for the measurement of the accuracy of the maximum power point tracking (MPPT) of inverters, which are used in grid-connected photovoltaic systems.
• Both the static and dynamic MPPT efficiency is considered.
• Based on the static MPPT efficiency and conversion efficiency the overall inverter efficiency is calculated.
• The dynamic MPPT efficiency is indicated separately.

UL 1741 (Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources), Key Points[3]:

• These requirements cover inverters, converters, charge controllers, and interconnection system equipment (ISE) intended for use in stand-alone or grid-connected power systems.
• For utility-interactive equipment, these requirements are intended to supplement and be used in conjunction with IEEE 1547 and IEEE 1547.1.
• These requirements cover AC modules that combine flat-plate photovoltaic modules and inverters; and power systems that combine other alternative energy sources with inverters, converters, charge controllers, etc.
• These requirements also cover power systems that combine independent power sources with inverters, converters, charge controllers, etc.
• The products covered by these requirements are intended to be installed in accordance with the National Electrical Code, NFPA 70.

IEC 61683 (Power conditioners – Procedure for measuring efficiency), Key Points[4]:

• This standard describes guidelines for measuring the efficiency of power conditioners used in stand-alone and utility-interactive photovoltaic systems.
• Applicable to cases where the output of the power conditioner is a stable AC voltage of constant frequency or a stable AC voltage.
• The efficiency is calculated from a direct measurement of input and output power in the factory.
• An isolation transformer is included where it is applicable.

IEC 62109-1 (Safety of Power Converters for Use in Photovoltaic Power Systems – Part 1: General Requirements), Key Points[5]:

• This part of IEC 62109 applies to the power conversion equipment (PCE) for use in Photovoltaic (PV) systems where a uniform level of safety is necessary.
• This standard defines the minimum requirements for the design and manufacture of PCE for protection against
  • Electric shock,
  • Energy,
  • Fire,
  • Mechanical, and
  • Other hazards.
• This standard provides general requirements applicable to all types of PV PCE.
• This standard has not been written to address characteristics of power sources other than photovoltaic systems, such as wind turbines, fuel cells, rotating machine sources, etc.

IEC 62109-2 (Safety of Power Converters for Use in Photovoltaic Power Systems – Part 2: Particular Requirements for Inverters), Key Points[6]:

• Part 2 of IEC 62109 covers the particular safety requirements relevant to DC to AC inverter products intended for use in photovoltaic power systems.
• Inverters are covered by this standard.
  • Maybe grid-interactive, stand-alone, or multiple mode inverters,
  • May be supplied by single or multiple photovoltaic modules grouped in various array configurations, and
  • May be intended for use in conjunction with batteries or other forms of energy storage.
• Throughout this standard where terms such as “grid-interactive inverter” are used, the meaning is
  • either a grid-interactive inverter, or
  • a grid-interactive operating mode of a multi-mode inverter.
• This standard does not address grid interconnection requirements for grid-interactive inverters.

[1] Extracted in the original form from BS EN 50524:2009 (Datasheet and name plate for photovoltaic inverters), published in January 2010. [2] Extracted in the original form from BS EN 50530:2010+A1:2013 (Overall efficiency of grid connected photovoltaic inverters), published in May 2010. [3] Extracted in the original form from UL Standard 1741, Edition 2 (Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources), published in 2010-01-28. [4] Extracted in the original form from IEC 61683 ed1.0 (Photovoltaic systems - Power conditioners - Procedure for measuring efficiency), published in 1999-11-25. [5] Extracted in the original form from IEC 62109-1 ed1.0 (Safety of power converters for use in photovoltaic power systems - Part 1: General requirements), published in 2010-04-28. [6] Extracted in the original form from IEC 62093 ed1.0 (Safety of power converters for use in photovoltaic power systems - Part 2: Particular requirements for inverters), published in 2001-06-23.