If you've been putting off solar until after the holidays, this one is for you. Two months remain in 2026, and on January 1 the rules for Hawai'i's state solar tax credit change. Whether a system you sign for today qualifies for the full 35% credit depends on a handful of dates, and some of them aren't as simple as "install by December 31."
Here's a plain-language look at where the credit stands on November 1, what a November start realistically means, and what Act 24 changes for anyone who goes solar in 2027 and beyond.
The federal 30% homeowner credit is already gone. It ended for systems placed in service after December 31, 2025. What remains is Hawai'i's own 35% state credit, up to $5,000 for a single-family solar PV system (and up to $2,250 for a solar water heater). Unused credit carries forward, so it isn't lost if your tax bill is small.
Then came Act 24, signed May 21, 2026. It keeps the 35% rate and the per-system limits, but adds a statewide cap and a sunset. Governor Green followed in June with Executive Order 26-02, which protects many 2026 systems from the new cap. That order is the reason timing matters so much right now.
Here's the honest answer: it depends, and the details matter. Under Executive Order 26-02, a system is exempt from the new cap when it is placed in service in 2026 and the owner can show they reasonably relied on the credit by taking steps to finance, plan, design, permit, or install it before May 21, 2026. The Department of Taxation addressed this in guidance on July 31.
"Placed in service" means installed, inspected, and approved to operate, not just signed. Hawai'i projects typically take two to four months from contract to permission to operate. A contract signed in November will, for most homes, finish after the calendar turns to 2027. We'd rather tell you that now than have you find out at tax time.
For taxable years after December 31, 2026, Act 24 changes how the credit works in several ways. The state is also still publishing implementation guidance, so confirm specifics with a tax professional before you file.
In other words, the credit doesn't vanish on January 1, but it becomes less predictable. The 35% rate may be reduced to your share of a limited pool, and you'll wait until spring to learn the number. That uncertainty is a real cost to weigh in any 2027 payback estimate.
Even with a smaller or less certain credit, the core economics are strong. Hawaiian Electric customers paid about 40¢ per kWh on O'ahu and 42¢ on Maui in 2025, among the highest rates in the country, and HECO has asked regulators for a base-rate increase starting January 2027. Every kilowatt-hour your roof makes is one you don't buy.
The market is also proving the demand. Hawaiian Electric connected 3,429 rooftop systems in the first half of 2026, about 36 megawatts, with O'ahu accounting for 2,505 of them. Roughly half of O'ahu's single-family homes now have solar. Homeowners are adding batteries alongside, and HECO's BYOD Plus program pays $400 per kW committed for batteries that support the grid in the evening.
One more incentive worth knowing about if hot water is a big part of your bill: Hawaii Energy offers up to $2,750 toward a solar water heater through June 30, 2027, while funds last.
Solar plus battery systems sized to your evening usage, honest timelines, and a clear read on the 2026 and 2027 state credit rules. Local and family-owned since 2007.
