Hawaii is unlike every other state in this calculator. Three things make it unique in 2026:
- Electricity is the most expensive in the US — about ~40¢/kWh on Oahu (range ~$0.35–$0.42 across islands), driven by imported fuel for the grid.
- Traditional net metering has been dead since 2015 — Hawaii was the first US state to end it. New residential customers are on Customer Grid-Supply Plus (CGS+) or Customer Self-Supply (CSS), both of which value exports far below retail.
- A battery is practically essential, not optional. Without one, the midday solar you produce gets exported cheaply (or earns nothing on CSS) instead of offsetting your $0.40 retail bill later.
The combination gives Hawaii the shortest solar-only payback in our verified set — about ~4.2 years based on retail offset alone. But the calculator number alone undersells what's going on: in Hawaii, the battery is part of the system economics, not a resilience add-on. This is the one state where a home battery actually pays itself back rather than just stretching payback for backup value.
What changed — and what didn't (in 2026)
The federal Residential Clean Energy Credit (§25D) — the 30% homeowner credit — was repealed for systems installed after December 31, 2025. For 2026 Hawaii buyers, the federal credit on a purchased system is $0. The same applies to home batteries purchased outright. The §48E commercial credit (30%) still exists, but only for leased or third-party-owned systems — the lessor claims it, not you. Full federal context here.
A note on Hawaii-specific federal misinformation: a lot of HI-focused solar coverage still cites a live "30% federal credit," including on batteries. Both are gone for 2026 residential purchases.
The other thing to flag is state-level: a lot of HI solar coverage still says "Hawaii has net metering." That hasn't been true since 2015. If a quote, article, or contractor proposal still describes "net metering" in Hawaii, the math is using an outdated rule.
VERIFIED 2026-06 · irs.govNet metering has been dead since 2015 — what replaced it
Hawaii was the first US state to end traditional 1:1 net metering, in 2015, driven by the highest residential solar penetration in the country at the time and growing grid-stability concerns. New residential customers since then choose between two programs:
- Customer Grid-Supply Plus (CGS+). Exports are credited at roughly ~$0.10–$0.28/kWh depending on island, time of day, and program vintage. This calculator models $0.15/kWh as a conservative estimate — your specific CGS+ rate may be higher or lower. Check with your utility.
- Customer Self-Supply (CSS). Exports earn essentially nothing — any energy not used on-site is uncompensated. CSS is built around the assumption that you have storage.
Self-consumed solar still offsets the full ~40¢/kWh retail rate, regardless of which program you're on. That's the value worth capturing, and it's why a battery matters so much in Hawaii.
Programs and tariffs vary by island: HECO (Oahu, modeled here), MECO (Maui), HELCO (Big Island), and KIUC (Kauai co-op). Each utility has its own rates and program vintages — verify your specific plan before sizing a system.
VERIFIED 2026-06 · Hawaii CGS+ tariff; HECO (net metering ended 2015)The driver: ~40¢/kWh retail
Hawaii's retail electricity is the highest in the United States. On Oahu the residential rate averages ~40¢/kWh (range across islands roughly $0.35–$0.42). The reason is structural: Hawaii's grid runs largely on imported fuel, so rates track fuel prices and shipping costs in a way mainland grids don't.
For solar, this means every kWh you produce and use immediately is worth about 40¢ of avoided bill. That's roughly:
- 3× what Florida solar avoids (~$0.14/kWh).
- 2× what Massachusetts solar avoids (~$0.30/kWh).
- More than California average retail (~$0.34/kWh).
That's how a solar-only system can pay back in ~4 years in Hawaii despite a dead federal credit and an export rate that's well below retail.
VERIFIED 2026-06 · eia.govRETITC: 35% up to $5,000 — and a new Act 24 caveat
Hawaii's Renewable Energy Technologies Income Tax Credit (RETITC) under HRS §235-12.5 is one of the strongest state solar credits in the US:
- 35% of system cost, capped at $5,000 for single-family residential.
- Carries forward if it exceeds your state tax liability.
- Sometimes refundable, depending on filer status.
- Covers a solar-paired battery installed in the same tax year as the PV system.
For most residential systems the $5,000 cap binds — a $15,000 system would earn $5,250 at 35% but gets capped at $5,000. Either way, it's a material chunk of system cost.
New for 2026: On May 21, 2026, Hawaii signed Act 24, which added a $40 million statewide annual aggregate cap on RETITC. Executive Order 26-02 protects 2026 projects that relied on the credit before May 21. For an individual 2026 buyer, the 35% / $5,000 individual cap still applies — but the new aggregate cap is a fresh development that almost no HI solar coverage written before May 2026 reflects. Verify the current state of the program with the Hawaii Department of Taxation before signing.
VERIFIED 2026-06 · Hawaii RETITC HRS §235-12.5; Act 24 (May 21, 2026); EO 26-02Exemptions: no statewide sales tax, county property tax
Sales tax. Hawaii has no statewide general sales tax, so there's no sales tax to apply to solar equipment. (Hawaii's General Excise Tax is structurally different — it's a tax on business gross receipts, not a consumer-side sales tax — and it isn't equivalent to a sales-tax exemption in other states. The practical result for a buyer is the same: no sales tax line item.)
Property tax. Property tax exemptions on the added home value from solar vary by county. The City and County of Honolulu offers a 25-year exemption on added value — strong by any standard. Maui, Hawaii County, and Kauai have their own rules. Check with your county assessor before assuming.
Battery in Hawaii — the section that's different here
Every other state guide on this site has a section pointing out that a battery is mostly a resilience purchase, not a payback shortener. Hawaii is the exception. Read this section carefully if you're sizing a system.
Hawaii has the highest residential battery attachment rate in the US for a specific economic reason. With net metering dead and exports valued at ~$0.15 (CGS+) or near-zero (CSS) while retail is $0.40, every kWh you can shift from "exported now" to "self-consumed later" is worth ~$0.25 of arbitrage value. That's the largest retail-vs-export gap in our verified set — comparable to California NEM 3.0 ($0.26), but paired with higher absolute retail.
In practical terms:
- Without a battery, ~30% of your annual production gets exported cheap (CGS+) or earns nothing (CSS) instead of offsetting expensive retail.
- With a battery, most of that exported production gets shifted to evening self-consumption at ~$0.40.
- That's the difference between solar capturing maybe ~70% of its theoretical value vs ~90%+.
The economic case isn't that the battery alone pays back at $13,000+ capex — even in Hawaii, a battery's pure arbitrage value doesn't fully cover its install cost within a typical residential horizon. The case is that the battery captures value the solar system would otherwise lose, and that the system + battery together pays off faster than solar-only in capture-rate terms.
Specifics worth knowing:
- RETITC covers a solar-paired battery installed in the same tax year as the PV — but the $5,000 individual cap typically binds on the solar side alone, so it doesn't add a fresh $5,000 for the battery. (It does protect a stand-alone battery installed with PV from losing access entirely.)
- Federal credit on battery purchase: $0 (§25D repealed). Ignore quotes that still show 30%.
- HECO Battery Bonus closed in July 2024. Current grid-services and BYOD (bring-your-own-device) programs vary by island and program year — ask HECO/MECO/HELCO/KIUC directly.
If you contrast Hawaii with the 1:1 retail net metering states (Florida, Virginia, New Mexico, Colorado, Massachusetts, New Jersey, New York legacy, Maryland), the difference is sharp. In those states the retail-export gap is zero — a battery has no arbitrage value, and its case is purely resilience. In Hawaii, the gap is the largest in our set, and the battery is part of how the system works economically.
The honest picture
Hawaii solar in 2026:
- Federal credit: $0. Not 30%. Discount any quote that still cites federal — including on batteries.
- Net metering has been DEAD since 2015. Discount any source that still describes "net metering in Hawaii."
- Export under CGS+: ~$0.10–$0.28/kWh (modeled at $0.15 as a conservative estimate). Under CSS: ~$0 (no compensation).
- Self-consumption: full retail ~$0.40/kWh — the highest in the US.
- Retail rate: ~40¢/kWh on Oahu ($0.35–$0.42 across islands), highest in the US.
- State credit RETITC: 35% / $5,000 cap (HRS §235-12.5), carryforward, sometimes refundable. Covers solar-paired battery same tax year.
- Act 24 (May 21, 2026): NEW $40M statewide aggregate RETITC cap. EO 26-02 protects 2026-projects before May 21. Individual 35% / $5,000 cap still applies. Verify with Hawaii DoTax.
- Sales tax: no statewide sales tax — no sales tax to apply.
- Property tax: county-level; Honolulu offers a 25-year exemption; other counties vary.
- Battery: practically essential, not optional. Largest retail-vs-export gap in our verified set (~$0.25). Hawaii has the highest US residential battery attachment rate. RETITC covers paired battery. HECO Battery Bonus closed July 2024.
- Typical solar-only payback: ~4.2 years — shortest in our set. With battery and proper sizing, the system captures meaningfully more lifetime value than the solar-only number implies.
Hawaii is the one state where the framing isn't "solar pays off, and a battery is a separate resilience question." It's "the system is solar + battery, and that's how the math works." If you're sizing a system in Hawaii, the right comparison isn't whether to add a battery — it's how to size one given your load profile, your island's CGS+ rate, and whether you're going CGS+ or CSS.
Before you commit:
- Discard any quote that still cites a 30% federal credit — including on battery — or describes "Hawaii net metering" as if it's current. Both are out of date.
- Pick CGS+ or CSS deliberately with your installer — they imply different battery sizing.
- Confirm whether you're on HECO, MECO, HELCO, or KIUC — rates and programs vary by island.
- Confirm your county property tax exemption status — Honolulu's 25-year is generous, others vary.
- Verify the RETITC aggregate cap status with the Hawaii Department of Taxation before signing — Act 24 is recent enough that processing details may still be settling.
- Plan for a battery as part of the system, not as a separate purchase to consider later.
- Run the calculator with your actual ZIP and system size, and try the battery toggle — in Hawaii, both numbers are worth looking at.
Estimates only — export rates and RETITC status vary by island and are subject to Act 24 changes; verify with your utility (HECO / MECO / HELCO / KIUC) and the Hawaii Department of Taxation. This is not financial advice.