It seems like everyone who purchases photovoltaic modules in the US is verifying whether the modules are UL listed.

What does that mean and where does the concern come from?

Well here is the latest of what we find.

The requirement really comes from the National Electric Code (NEC), but the requirement does not directly specify that the listing should be by UL (Underwriters Laboratories – a company).

The exact requirement states:

“…

Chapter 6 Special Equipment

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ARTICLE 690—SOLAR PHOTOVOLTAIC SYSTEMS

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690.4 Installation.

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(D) Equipment. Inverters, motor generators, photovoltaic modules, photovoltaic panels, ac photovoltaic modules, source-circuit combiners, and charge controllers intended

for use in photovoltaic power systems shall be identified and listed for the application.

…”

In section 100 there is the definition for listed:

“…

Chapter 1 General

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ARTICLE 100—DEFINITIONS

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Listed. Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.

FPN: The means for identifying listed equipment may vary for each organization concerned with product evaluation, some of which do not recognize equipment as listed unless it is also labeled. Use of the system employed by the listing organization allows the authority having jurisdiction to identify a listed product.

…”

In the same article we look up the definition for Authority Having Jurisdiction (AHJ).

“…

Authority Having Jurisdiction (AHJ). An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure.

FPN: The phrase “authority having jurisdiction,” or its acronym

AHJ, is used in NFPA documents in a broad manner, since jurisdictions and approval agencies vary, as do their responsibilities. Where public safety is primary, the authority having jurisdiction may be a federal, state, local, or other regional department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor department, or health department; building official; electrical inspector; or others having statutory authority. For insurance purposes, an insurance inspection department, rating bureau, or other insurance company representative may be the authority having jurisdiction. In many circumstances, the property owner or his or her designated agent assumes the role of the authority having jurisdiction; at government installations, the commanding officer or departmental official may be the authority having jurisdiction.

…”

(this is for reference purposes only; the NEC text is copyrighted and isolated use of extracted instructions from it may be very insufficient for many purposes)

Ok so, obviously UL is considered to be “an organization that is acceptable to the authority having jurisdiction” as worded in Article 100 and ties in with the Article 690 point 690.4 (D) for photovoltaic equipment. So it’s is widely accepted that a UL listing (and labeling) assures that the equipment meets the NEC requirements.

What about other testing organizations though? There is no reason for monopoly of UL.

Well we are not able to find a list of such organizations but we came across information about one more company that does testing – Intertek ETL SEMKO. They state that their ETL labeling and listing is as good as the UL one.

Here is what they say on a brochure you can look up here.

(Click here for the Intertek ETL SEMKO brochure.)

“…

When it comes time to test your products to North American product safety standards, you may be led to believe that your choices are limited to certain marks, such as the UL Listed Mark. In reality, there are others equally recognized and accepted — prominent among them, the ETL Listed Mark issued by the ETL SEMKO division of Intertek.

…”

(again we are only quoting here for the purpose of supporting this article; Intertek’s text is copyrighted and all trade marks are their ownership)

The whole brochure is an interesting reading on the topic.

So we are finding that UL is not the only possible listing that solar panel manufactures can chose. A lot of new manufactures are suffering from the time it takes UL to start and complete the process if testing them and listing them. Some of them report that ETL is quicker to get, not because the testing and inspecting takes less time but because it is a company that at least for now offers less waiting to start working on the certification.

I guess the issue is still open, though, depending on what the AHJ will decide about “an organization that is acceptable to the authority having jurisdiction”. May be some state or local authorities, or insurance companies will have their own list of organizations that are acceptable.

All trademarks are property of their respective owners and are only displayed here as a reference.

Please, as always, feel free to comment on this. The opinion of people who have experience of going through the inspection process or getting a system insured is especially important.

In the latest version of the Resources page we have interesting reference to information on UL listing of solar equipment.

SolarByTheWatt.com