UL 3700 explained
UL 3700 is UL Solutions' Outline of Investigation for Interactive Plug-In Photovoltaic Equipment and Systems. UL Solutions uses it as the basis of its plug-in solar certification program, so a device certified under that program is listed against UL 3700. Some state laws name it directly. Others require a different standard, or use broader nationally recognized testing laboratory wording.
State laws that name UL 3700
Maine's law requires a system "listed or certified in accordance with UL 3700" or a comparable standard from a nationally recognized testing laboratory. Vermont's act requires that a device "complies with UL 3700 for plug-in photovoltaic systems by UL Solutions or an equivalent certification by an equivalent Nationally Recognized Testing Laboratory."
State laws that use different wording
UL 3700 is not universal. Connecticut names UL Standard 1741, along with the National Electrical Code, IEEE 1547, and the state building code. Utah, Maryland and New Jersey require certification by Underwriters Laboratories or an equivalent nationally recognized testing laboratory, without naming UL 3700. Colorado uses nationally recognized testing laboratory listing in its device definition, with a separate rule from January 1, 2027 requiring devices over 391 W to be "UL labeled and listed" before sale. New Hampshire uses broader nationally recognized testing laboratory language, and Virginia requires certification by a nationally recognized testing laboratory "as described in 29 C.F.R. ยง 1910.7." Read each linked statute for the exact requirement.
What a nationally recognized testing laboratory is
A nationally recognized testing laboratory, or NRTL, is a laboratory that OSHA has recognized to test and certify products against consensus safety standards. UL Solutions is one NRTL among several. A law that uses NRTL wording is broader than one that names UL specifically, because it accepts certification by any recognized laboratory.
How to check a UL listing
UL Solutions maintains a public certifications directory. A certified product appears there with a file number and the standard it was evaluated against. A manufacturer's claim that a product "meets" or "is designed to" a standard is not the same as a listing in that directory.