UL 3700
By Priya Nair · Last reviewed The Outline of Investigation for Plug-in Photovoltaic Systems, published by UL Standards & Engagement in December 2025 — the first US safety document written for the plug-in system as a whole rather than its components. State laws such as Utah's HB 340 reference it as the qualifying safety condition.
Why it matters
UL 3700 is the hinge of the US market: laws are written around it, yet as of mid-2026 no product holds verified system-level certification against it. Understanding what an outline is (testable now, not yet a consensus ANSI/UL standard) is the key to reading every certification claim in the category.