US solar industry attacks tightened safe harbour rules for ITC qualification

The US Treasury Department has implemented stricter "start of construction" rules for renewable energy projects seeking federal tax credits, replacing the prior 5% cost safe harbor with a "Physical Work Test" for projects over 1.5MW. This change, stemming from an executive order, has drawn sharp criticism from US solar industry associations, including SEIA, who argue it undermines clean energy development and congressional intent. Industry leaders warn these new requirements will increase project costs and complexity, potentially hindering solar capacity buildout and raising electricity prices by making tax credit qualification more difficult.

Analysis

The US Treasury Department has introduced a significant regulatory tightening for renewable energy projects, creating considerable uncertainty and execution risk for the US solar industry. Effective from September 2, 2025, for projects over 1.5MW, the traditional 5% cost-based safe harbor provision for initiating construction to secure federal tax credits will be replaced by a more stringent "Physical Work Test." This new test requires evidence of "physical work of a significant nature," such as the manufacturing of key components or on-site installation of structures, while explicitly excluding preliminary activities like planning or site clearing. This change, driven by a presidential executive order, is viewed by industry leaders from SEIA, CCSA, and ACP as a direct move to undermine the recently passed One, Big, Beautiful Bill Act (OBBBA), creating "new federal red tape" that will make projects "more difficult and expensive to build." The move is expected to negatively impact the pace of solar deployment, with a Clean Energy Associates report highlighting a potential loss of up to 60GW of planned capacity by 2030 under harsh rule interpretations, ultimately threatening to raise electricity costs and slow the US energy transition.

Key Decisions for Investors

• Investors should immediately reassess US solar project pipelines, as the shift from a 5% cost safe harbor to a 'Physical Work Test' introduces significant new timing and execution risks for developments over 1.5MW.
• The new rules emphasize manufacturing of key components as proof of construction start, potentially creating a strategic advantage for vertically integrated developers or domestic renewable equipment manufacturers; exposure to this segment of the supply chain should be reviewed.
• Given the intense industry criticism and accusations of bypassing congressional intent, it is prudent to monitor for potential legal challenges or future legislative actions that could reverse or amend these new Treasury guidelines.
• The heightened regulatory burden and potential for project delays warrant a more cautious outlook on the near-term growth rate of US solar capacity, justifying a review of companies highly dependent on a rapid pace of new project commencements.