Why is UL 916 important for solar PV products?

Solar PV products have gained popularity as sustainable and renewable energy sources. As demand increases, it's crucial to establish safety standards to ensure their quality and reliability.

UL 916 is one such standard, specifically for energy management equipment in solar PV systems. In this post, we will discuss the importance of UL 916 for solar PV products and how it contributes to their safety and performance.

UL 916: Standard for Energy Management Equipment

UL 916 is a crucial safety and performance standard for energy management equipment utilized in solar PV systems.

The standard covers a broad spectrum of components, with inverters, battery systems, and all related parts included. It meticulously outlines the safety requirements for these components, providing extensive detail.

This standard is of great importance for manufacturers, installers, and end-users alike since it ensures that solar PV products are dependable, efficient, and safe to use.

The UL 916 requirements play a pivotal role in preserving high-quality energy management equipment throughout the solar industry.

Electrical safety requirements

The electrical safety requirements in UL 916:


Insulation is a critical requirement for solar PV energy management equipment.

It aids in preventing electrical current from flowing in unintended directions, which can result in electric shock, equipment damage, and fire hazards.

According to UL 916, energy management equipment must be designed and built using appropriate insulation materials and techniques.

The standard also specifies the amount of insulation required as well as the minimum distance between conductive parts.


Another essential requirement for electrical safety in solar PV systems is grounding.

Solar Panel Cable Wiring in Solarfarm

In the event of a fault, grounding provides a safe path for electrical current to flow, assisting in the prevention of electric shock and other hazards caused by excess current.

UL 916 specifies the minimum size and number of ground conductors required for energy management equipment.

The standard also specifies ground connection resistance and the maximum allowable voltage between ground and conductive parts.

Example of Grounding Requirement under UL 916:

Consider an energy management system that consists of a central controller and multiple power-consuming devices, such as HVAC systems, lighting, and appliances, connected to it.

The controller monitors and regulates the energy consumption of the connected devices.

According to UL 916, the grounding requirement for this energy management system would include:

  1. The central controller and any connected devices must be grounded with an appropriate grounding conductor. The grounding conductor should be connected to the controller's equipment grounding terminal as well as the grounding terminal of each device. The grounding conductor should be sized according to the National Electrical Code (NEC).
  2. Grounding connections should be made with proper connectors, such as grounding lugs or screws, to ensure secure and reliable connections.
  3. Any metallic enclosures, such as cabinets or junction boxes, that house the controller or other devices should also be grounded to reduce the risk of electric shock or equipment damage caused by voltage surges, lightning strikes, or other external influences.
  4. The proper grounding of the energy management system should be verified through visual inspection and testing in accordance with the procedures outlined in UL 916.

By adhering to these grounding requirements, the energy management system can safely operate while minimizing the risks associated with electrical faults and other hazards.

Overvoltage Protection

It is crucial to protect energy management equipment from potential damage caused by voltage spikes or power surges. Overvoltage protection plays a vital role in reducing risks and maintaining optimal functionality.

As per UL 916, energy management equipment must incorporate appropriate overvoltage protection devices, such as surge protectors or voltage limiters.

The standard also establishes stringent requirements regarding the maximum voltage the equipment can withstand and the permissible voltage applied to the equipment.

Example of Overvoltage Protection under UL 916:

Consider a demand response system used for managing peak energy loads in a commercial building.

This system comprises a central control unit, connected to various electrical devices like HVAC systems, lighting, and appliances, and receives signals from the utility company to adjust energy consumption in response to grid conditions.

To provide overvoltage protection under UL 916 for this demand response system, the following measures should be taken:

  • Surge Protective Devices (SPDs): Install SPDs at critical points within the system, such as the main electrical panel and the control unit, to protect the connected devices from voltage spikes or surges that may result from lightning strikes, switching operations, or other external factors. SPDs should meet the requirements of UL 1449, the standard for Surge Protective Devices.
  • Voltage Limiting Components: Incorporate voltage-limiting components, such as metal oxide varistors (MOVs), transient voltage suppressor (TVS) diodes, or Zener diodes, into the system's design to prevent excessive voltage levels from reaching sensitive components in the control unit and connected devices. These components should be rated for the maximum voltage levels that the system may encounter and be properly sized to handle the potential energy surge.
  • Circuit Breaker or Fuse Protection: Install circuit breakers or fuses on the power supply lines of the control unit and connected devices to provide an additional layer of overvoltage protection. Circuit breakers or fuses should be rated according to the system's voltage and current specifications, and be compliant with the National Electrical Code (NEC) requirements.
  • Monitoring and Control: Integrate voltage monitoring functionality into the control unit, allowing it to continuously monitor the system's voltage levels. If an overvoltage condition is detected, the control unit should be programmed to take appropriate actions, such as disconnecting affected devices or shutting down the entire system to prevent damage and maintain safety.
  • Proper System Design: Ensure that the entire energy management system, including the control unit and connected devices, is designed to handle voltage fluctuations and overvoltage conditions. This could involve selecting components with sufficient voltage ratings, using electrical isolation techniques, and employing redundant power supply systems to maintain safe operation under varying conditions.
  • Equipment Ratings and Compliance: Verify that all devices and components within the energy management system, including the control unit, connected devices, and overvoltage protection measures, comply with the relevant UL standards and the NEC. This helps ensure that the system can withstand overvoltage conditions safely and reliably.
  • Regular Maintenance and Testing: Establish a regular maintenance schedule and conduct periodic testing of the overvoltage protection measures to ensure their proper functioning. This may involve inspecting the surge protective devices and voltage-limiting components for signs of wear or damage, testing the circuit breakers or fuses for proper operation, and verifying that the control unit's voltage monitoring and response capabilities are functioning as intended. Regular maintenance and testing will help identify potential issues before they become critical and maintain the overall safety and reliability of the energy management system.

These overvoltage protection measures and UL 916 requirements allow the commercial building's demand response system to operate safely and effectively while minimizing voltage-related damage and hazards.

This ensures grid-responsive energy management and building electrical system safety.

Short-Circuit Protection

The excess current flow causes equipment damage and potential fire hazards, so short-circuit protection is critical.

Energy management equipment must be equipped with appropriate short-circuit protection devices, such as circuit breakers or fuses, according to UL 916.

The standard also specifies the maximum current that can be applied to the equipment as well as the maximum current that the equipment can withstand.

Mechanical safety requirements

The mechanical safety requirements in UL 916:

Structural Strength

The structural strength of energy management equipment used in solar PV systems is critical.

These products must be designed and built to withstand mechanical stresses and loads encountered during installation, operation, and maintenance.

UL 916 specifies structural strength requirements for energy management equipment, such as the maximum load that the equipment can withstand and the minimum thickness of parts and components.

Protection Against Physical Damage

Physical damage protection is another critical requirement for mechanical safety in solar PV systems.

Physical impacts, vibration, and other environmental factors must be protected against damage to energy management equipment.

UL 916 specifies requirements for the enclosure protection of energy management equipment, such as the minimum enclosure thickness, impact and vibration resistance, and moisture and dust sealing.

Protection Against Environmental Factors

Protection from environmental factors, including moisture and dust, is essential for the safe and efficient operation of energy management equipment in solar PV systems.

The UL 916 standard details specific requirements for environmental protection of such equipment, addressing dust and moisture resistance, UV radiation resilience, and the capacity to perform under various temperature and humidity conditions.

Performance requirements

The performance requirements in UL 916:

Maximum Power Output

The maximum power output of energy management equipment used in solar PV systems is one of the crucial performance requirements.

Energy management equipment must meet UL 916 specifications for their maximum power output in order to deliver the anticipated power output and function safely.


Efficiency is a crucial performance aspect of energy management equipment. UL 916 establishes requirements concerning the efficiency of this equipment, guaranteeing that it converts the highest amount of solar energy into electricity while minimizing energy loss.

Accuracy of Energy Measurement

Accuracy in measuring energy production and consumption is essential for energy management equipment in solar PV systems.

UL 916 defines requirements for energy measurement accuracy, ensuring that energy management equipment adheres to industry standards. For instance, a solar energy meter may need to maintain an accuracy of +/- 2%.

Environmental requirements

Here are the environmental requirements for UL 916:


Energy management equipment used in solar PV systems must be designed to operate within a range of temperatures.

UL 916 specifies requirements for the minimum and maximum temperatures that energy management equipment can operate in, ensuring that they can function in extreme heat or cold.


Humidity can also affect the performance and safety of energy management equipment used in solar PV systems.

UL 916 sets requirements for the maximum humidity levels that energy management equipment can operate in, ensuring that they can operate safely and effectively in humid conditions.


Energy management equipment used in solar PV systems must also be able to operate at various altitudes.

UL 916 sets requirements for the maximum altitude that energy management equipment can operate at, ensuring that they can operate safely and effectively at high altitudes.

Compliance with UL 916 for Solar PV Products

The safety requirements for solar photovoltaic (PV) products are addressed specifically in UL 916. This covers the products' design, construction, functionality, and materials employed during production.

Manufacturers are required to go through testing and certification procedures that include evaluation of the product's electrical and mechanical performance, as well as its safety features and protective measures.

An assessment of the product's installation, use, and maintenance needs is also a part of the testing process.

Additionally, manufacturers are required to maintain compliance with evolving standards and legal requirements. This entails adhering to any new regulations or requirements that may emerge, as well as staying current with modifications to UL 916 and other pertinent standards.

Manufacturers benefit from UL 916 compliance by improving product quality and reliability, adhering to industry standards and regulations, and gaining the trust and confidence of customers.

Compliance with UL 916 benefits end users by ensuring their safety as well as improving product reliability and quality.


Finally, UL 916 is a critical safety standard for solar PV products. Compliance with UL 916 ensures end-user safety, improves product reliability and quality, meets regulatory and industry standards, and builds consumer trust and confidence.

While there are challenges associated with compliance, prioritizing safety and investing in compliance is critical for the solar PV industry's success and growth.