Permitting pathways for floating photovoltaic projects in Thailand: licenses, competent authorities, and the limits of the rooftop exemption

Floating photovoltaic (FPV) deployment in Thailand is expanding on irrigation reservoirs, hydropower reservoirs and industrial-estate ponds, yet the regulatory pathway a project must follow is documented only in law-firm client alerts and consultancy briefings that are not citable in scholarly work. This note reconstructs that pathway from primary Thai legal instruments. It identifies the competent authority, legal basis and triggering condition for each approval an FPV project requires, and distinguishes those that FPV shares with ground-mounted solar from those that arise specifically because the array sits on water. The note gives particular attention to a widely held misconception. The factory category covering solar generation has, since it was made in B.E. 2563, been defined by reference to an exclusion for installations on roofs, terraces and parts of buildings; floating arrays have never fallen within that exclusion. The relief granted to rooftop solar in December 2024 widened the exclusion but did not extend it to any new class of installation. Reports that "solar no longer requires a factory license" in Thailand are accordingly incorrect as applied to FPV, and were never correct of it. The note is intended as a citable reference for the regulatory-context paragraphs that FPV siting, techno-economic and policy studies routinely require but cannot presently source.