UL Listing for Solar Lighting Systems

Independent Safety Testing

Underwriters Laboratories (UL) is the most widely recognized Nationally Recognized Testing Laboratory (NRTL) in the world and creates most of the standards that all other NRTL’s use for testing. We will refer to UL through the rest of this page; ETL, TUV and CSA may also be acceptable. Contact Urban Solar for more details.

Having a UL Listed Product means the manufacturer incorporates listed or recognized components as well as additional safety measures (fuses, breakers, wire terminal blocks, safety switches, etc.) and design considerations (wire routing and protection, component spacing, electrical panel layout, etc.) in order to meet NEC safety guidelines and functionality as described in the UL standards to which it is listed.

The complete assembled product is evaluated based on the individual internal components, their compatibility, and the complete finished product functionality and safety in its intended use environment.

So what defines a UL Listed product?

UL Listed Product means the manufacturer incorporates listed or recognized components as well as several additional safety measures (fuses, breakers, wire terminal blocks, safety switches, etc) and design measures in order to meet NEC safety design guidelines AND functionality as described in the UL standards to which it is listed.

The finished product has been rigorously tested and evaluated by UL engineers in accordance with appropriate UL and NEC standards. Installation manuals and testing/verification of any software and functionality are mandatory, and all parts are certified.

The manufacturing facility and products are routinely audited to ensure continued adherence to the standards, and all design changes or component substitutions must be approved by UL.

What are some evaluation criteria for a UL Listed solar lighting product?

Some of the additional design measures and evaluation criteria for a UL listed solar lighting product include:

  • All parts must be listed or recognized for their intended use.
  • Wire types and sizes/temperature ratings/UL listed only for the intended use.
  • Branch Circuit Protection – UL listed fuses and breakers to match solar array size and loads.
  • Field wiring terminals with labels indicating torque specifications etc.
  • Labelling of all field wiring terminals in accordance with wiring schematics.

The finished product must comply with certain requirements, including:

  • Wire-bending radius inside the control panel.
  • Appropriate interrupting capacity ratings.
  • Adherence to the latest national electric codes (finger-safe terminals, contact points).
  • Best wiring practices to ensure safety and functionality.
  • Proper separation of devices and terminals.
  • Dimensions and separation between penetrations to the control panel as well as proper sizing.

Some of the additional testing and evaluation criteria used by UL engineers include:

  • Frame and Enclosure – Environmental ratings, corrosion protection, wire and conduit openings, ventilation, mounting, and protection of users and service personnel.
  • Electrical Shock Hazards – Voltage and current ratings, stored energy, warnings, etc.
  • Electrical Protections – Control switches, disconnect devices, branch circuit protection, fuses and breakers.
  • Wiring – Wire types and ratings, environmental, field wired terminals, minimum bend radius, terminal spacing, wiring compartments, conduits, etc.
  • Grounding – Equipment grounding requirements, labelling, code compliant grounding/bonding.
  • Battery and PV Circuits – Branch circuit protection to NEC standards.
  • Maximum Operating Temperature – Products are tested for operation at maximum rated temperature and maximum rated electrical load output.
  • Rain Test – Simulated rain testing using calibrated sprinkler jets.
  • Product Marking – Product codes, ratings, warnings, symbols, and label materials.
  • Product Installation Manuals – Must include electrical schematics, assembly and mounting, grounding means, ventilation considerations, explanation of equipment markings and symbols, electrical ratings, operation of equipment – the installation instructions shall indicate that the wiring methods in accordance with the National Electrical Code, ANSI/NFPA 70 are to be used.
What if you're not sure that a solar lighting product is UL Listed?

If you’re not sure whether a solar lighting system is UL listed, or just a part of it, ask us. Our engineers can help you understand the standards for solar lighting equipment and how they may impact the success of your overall project.

There are a number of important things to consider when choosing a solar lighting vendor. Do NOT buy a solar lighting system for your project unless it is:

  • Made from UL-listed components recognized for their specific application;
  • Built according to UL standards; and
  • Verified through onsite inspections for adherence to the standards.

Making the effort to confirm that the chosen solar lighting system is designed, manufactured, and listed to strict UL standards will keep you out of trouble and save time, money and risk while improving the overall quality of your projects.

On-site field inspections by the Authority Having Jurisdiction (AHJ) in the USA

In these cases, the installed solar lighting system may be required to be inspected and accepted by a local inspector (AHJ) at each place of installation. For non-listed systems the manufacturer and buyer are relying on the opinion of these inspectors. Non-compliances to NEC safety standards then have to be remedied on site. This often results in extra costs and delays during commissioning.  Acceptance by AHJ’s leaves much of the decision making to individuals that have their own interpretations of what constitutes an NEC compliant and safe lighting system.  However, if the system is UL listed then AHJ approval, if required at all, is simply a matter of verifying the listing number.  No opinions or guesswork are required, and the AHJ is not liable.

The Authorities Having Jurisdiction (AHJ) can depend on the particular region and locale, but most will reference the National Electric Code (NEC), which lays out minimum requirements for protecting the safety of persons and property from injury and damage arising from the use of electricity.

Under the NEC, article 411 describes requirements for lighting systems operating under 30 volts or  connected to a Class 2 (less than 100W) power source.

Specifically, article 411 says:

Lighting systems operating at 30 volts or less shall comply with 411.3(A) or 411.3(B).


(A) Listed System. Lighting systems operating at 30 volts or less shall be listed as a complete system. The luminaires, power supply, and luminaire fittings (including the exposed bare conductors) of an exposed bare conductor lighting system shall be listed for the use as part of the same identified lighting system.

(B) Assembly of Listed Parts. A lighting system assembled from the following listed parts shall be permitted:

(1) Low-voltage luminaires
(2) Low-voltage luminaire power supply
(3) Class 2 power supply
(4) Low-voltage luminaire fittings
(5) Cord (secondary circuit) for which the luminaires and power supply are listed for use
(6) Cable, conductors in conduit, or other fixed wiring method for the secondary circuit
(7) The luminaires, power supply, and luminaire fittings (including the exposed bare conductors) of an exposed bare conductor lighting system shall be listed for use as part of the same identified lighting system.

Oftentimes it is a business decision that also involves development and insurance companies and their willingness to take on the liability of potential property damage and personal injury. While installing a non-listed lighting system may pose a significant shock and fire risk that companies are unwilling to take responsibility for, systems installed on an isolated Class 2 circuit may be considered low enough of a risk that a non-listed product would be approved.

In the event that an unlisted system does cause a fire, perhaps they would be able to maintain a strong position in court arguing that these should have been inherently safe in a Class 2 circuit, or perhaps not.

What if no AHJ or inspector is involved?

This is often the case for end-consumers who purchase non-listed products directly. The seller is not breaking any laws, and neither is the buyer. This is oftentimes the case with lesser-known brands and online sellers, and there is nothing inherently wrong or illegal with this arrangement.

In fact, buying and selling products without UL listing is not illegal either, however, the risks here are significantly higher, and buyers of these unlisted products take on significant injury and financial risk.

For manufacturers, receiving UL listing can be a costly process. But are there any benefits to paying the UL listing premium?

The overall benefit of UL is that they help to verify that the system has been engineered properly to function in its intended use, and the manufacturer’s design has incorporated all appropriate and necessary safety measures to ensure an NEC compliant product and installation.

This also helps to alleviate the burden of legal and financial risk. If property damage or personal injury arises from the non-listed product, for example, legal risks for both sides remain. For the seller, they would need to show that their product did not have any defects or design issues that contributed to the damage. For the buyer, their insurance companies may refuse to provide payment for damage claims due to their use of an unlisted product. In short, lawyers could potentially make the case that both the buyer and seller were negligent.

If property damage or personal injury arises from a UL listed product, on the other hand, both the buyer and seller can make a strong case that they trusted that the UL marking signified a certain level of confidence in the safety of the product, and therefore avoid the risk of any negligence claims.

The Bottom Line

Whether you are a manufacturer, distributor, contractor, or consumer, understanding the rules and regulations around UL listing for solar lighting products can be challenging but critical. For some projects, UL listing may be a prerequisite for approval, in which case you would have no choice but to seek only products which have received UL listing.

For other situations, however, it is less black and white, and more about your own assessment of the risks involved. It is certainly true that many of the risks of electric shock and fire are lower for systems operating under 30 Volts but that does not at all mean that they are eliminated or nonexistent. Be sure to consider all aspects of the situation, and when in doubt, consult a professional!