If your business is planning a commercial solar, battery, or EV charging project, timing just became the most important part of the conversation. A major federal rule change means the tax credit that has anchored commercial solar economics for over a decade now runs on a much tighter clock, and the projects that move now are the ones that will actually make the new deadline.
The New Deadline: December 31, 2027
Under the One Big Beautiful Bill Act, the federal Section 48E commercial Investment Tax Credit was restructured around a hard cutoff. Projects that began construction on or before July 4, 2026 still get the old, forgiving timeline: a four-year continuity safe harbor, meaning a project that broke ground in 2026 has until the end of 2030 to be placed in service and still collect the full 30% credit.
That July 4, 2026 date has already passed. Any commercial project beginning construction now falls under the new rule, and it is a strict one: the system must be placed in service by December 31, 2027 to qualify for the credit at all. There is no partial credit for missing it and no extension built into the law. From today, that leaves a little over 15 months.
What Counts as “Beginning Construction”
The IRS gives commercial projects two ways to establish a construction start date, and which one applies depends on system size. Projects at or under 1.5 MW (AC) can qualify through the “5% Safe Harbor,” incurring at least 5% of total project costs, or through the Physical Work Test. Projects larger than 1.5 MW must use the Physical Work Test only, meaning documented physical work of a significant nature, on-site or through a contracted off-site manufacturer, with the paper trail (contracts, invoices, site records) to prove it.
For most commercial and industrial buildings we work with in Orange County, that means the Physical Work Test is the relevant bar, and it needs to be met and documented properly, not assumed.
A Realistic Commercial Timeline
This is where the deadline gets tight. A commercial solar installation, start to finish, typically runs anywhere from four months for a straightforward rooftop system to nine to twelve months for a larger ground-mount or carport system with more complex engineering. Utility interconnection alone, through SCE or another local utility, commonly takes two to six months depending on grid capacity and whether a full interconnection study is triggered.
Add design and engineering, permitting through the local Authority Having Jurisdiction, equipment procurement, and installation on top of that, and it becomes clear why December 31, 2027 is not as far away as it sounds. A project that starts the permitting process today is already working against the clock; one that waits until spring 2027 to begin design may not make it at all.
The Bottom Line
If a commercial solar, battery storage, or EV charging installation has been on your radar, the smartest move right now is to get a site assessment and a realistic project timeline started, not to wait for a better moment. Between permitting, interconnection, and construction, most of 2027 is already accounted for before a single panel goes up. Want to know where your project would land on the calendar and what it would take to lock in the current 30% credit? Reach out to Energy-SBC for a free, no-obligation consultation and we’ll map out a timeline specific to your building and your utility.
Related reading: Learn more about commercial and industrial solar, our commercial case studies, EV charging for businesses, and working with general contractors. Have questions about your own project? Contact Energy-SBC for a free consultation.