Various standards and building codes apply to rooftop solar systems. Following are applicable standards. Click here to jump to building code information.
UL 1703, "Flat-Plate Photovoltaic Modules and Panels," provides an American National Standards Institute (ANSI) consensus process-developed basis for evaluating flat-plate solar modules and panels intended for use on or integrated with buildings. The standard also applies to modules or panels that are free-standing (not attached to buildings). UL 1703 provides specific requirements regarding the construction, performance, testing, rating and marking of solar module and panel products.
Solar module and panel products that satisfy UL 1703's requirements and are included in UL's follow-up service (verification of continuing manufacturing as originally evaluated) are eligible to be UL-certified and bear a UL listing mark label. Information about UL-certified solar modules and panels can be found by accessing www.ul.com, selecting "Certifications" and entering Category Code QIGU.
Solar module and panel products included in UL's certification program will bear a UL listing mark label, which includes the UL symbol, the word "listed," a control number and the words "Photovoltaic Module" or "Photovoltaic Panel." Also, listing mark labels for products that have been evaluated for their external fire resistances will denote "Class A," "Class B" or "Class C" depending on the specific external fire resistance achieved. The labels for solar module or panel products that have not been tested for their external fire resistances will indicate "Not Fire Rated."
UL 1741, "Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources," covers inverters, converters, charge controllers and interconnection system equipment intended for use in standalone (not grid-connected) or utility-interactive (grid-connected) power systems. Utility-interactive inverters, converters and interconnection system equipment are intended to be operated in parallel with an electric power system to supply power to common loads.
The products covered by UL 1741 are intended to be installed in accordance with NFPA 70: National Electrical Code (NEC).
UL 2703, "Standard for Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels," provides specific requirements for rack-mounting systems, mounting grounding and bonding components, and clamping and retention devices for specific flat-plate solar modules and panels that comply with UL 1703. This standard is intended for solar systems installed on or integrated with buildings, or to be freestanding, in accordance with the NEC, ANSI/NFPA 70 and model building codes. The requirements address rack mounting systems and clamping devices intended for use with solar systems with a maximum system voltage of 1,000 volts and only pertain to ground and bonding paths, mechanical strength and suitability of materials.
ASTM D3161, "Standard Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method)," sometimes is used to evaluate the wind resistance of solar modules and panels and their attachment to underlying substrates or rack-mounting systems. UL 997, "Wind Resistance of Prepared Roof Covering Materials," is similar to ASTM D3161 and sometimes is used by UL to classify the wind resistances of solar modules and panels.
ASTM E1038, "Standard Test Method for Determining Resistance of PV Modules to Hail by Impact with Propelled Ice Balls," provides a test method used to determine the ability of solar modules to withstand the impact forces of hailstones. The effects of impact may be either physical or electrical degradation of the module.
IEEE 1547, "Standard for Interconnecting Distributed Resources with Electric Power Systems," provides criteria and requirements for the interconnection of distributed generation resources into the power grid in the U.S.
IEEE 1547.1, "Standard for Conformance Test Procedures for Equipment Interconnecting Distributed Resources with Electric Power Systems," further describes the testing of the interconnection to determine whether it conforms to standards. It specifies the type, production and commissioning tests that shall be performed to demonstrate the interconnection functions and equipment of a distributed resource conform to IEEE 1547.
FM Approval Standard 4478, "Approval for Rigid Photovoltaic Modules," provides FM Approval requirements for rigid solar modules used in an FM-approved roof assembly. The standard is applicable to rigid solar modules intended to be mechanically fastened through or adhered to FM-approved single-ply, polymer-modified bitumen, built-up and liquid-applied roof membranes or steel-slope roof coverings; mechanically fastened or adhered to metal roof systems; or loose-laid and ballasted over fully adhered single-ply, polymer-modified bitumen or built-up roof membrane systems. FM 4478 also applies to panels secured to racks or rack framing that are independently secured to the building structure, roof deck or metal roof cover or ballasted. It also addresses the rack and rack securement.
Building code information
Building code compliance for rooftop-mounted solar systems is somewhat more complicated than it is for roof systems. In the I-code model codes published by the International Code Council (ICC), rooftop-mounted solar systems primarily are addressed in the International Building Code (IBC) in Chapter 15—Roof Assemblies and Rooftop Structures; International Residential Code for One and Two-family Dwellings (IRC) in Chapter 9—Roof Assemblies; International Fire Code (IFC) in Chapter 6—Building Services; and International Solar Energy Provisions (ISEP) in Chapter 6—Photovoltaic Systems.
For rooftop-mounted solar systems, all the applicable code requirements are not provided in a specific code chapter or single code. Instead, the applicable code requirements for rooftop-mounted solar systems are scattered in multiple chapters of multiple codes.
Before a rooftop solar system project is undertaken, the specific codes that apply to the project need to be determined. In some instances, codes are adopted at the state level; in other instances, codes are adopted at regional (county, parish, township) or local (municipal) levels by the authority having jurisdiction (AHJ). An AHJ has the authority to adopt model codes in their entireties, adopt a model code with locally developed amendments or develop its own code. Designers, manufacturers, suppliers and installers of rooftop-mounted solar systems are encouraged to inquire with an AHJ regarding the codes that apply, specific edition dates of the applicable codes and what specific permits are required.