Hawaii solar guide
DIY solar in Hawaii: incentives, sizing, and the off-grid angle
Hawaii has the highest residential electricity rates in the United States — typically $0.34–$0.45 per kWh, more than 3x the national average. That makes the solar payback math the most favorable in the country. A well-sized residential system can pay back in 4–6 years even with modest export compensation.
The catch: HECO closed traditional 1:1 net metering in 2015. Your two modern options are Customer Self-Supply (no export — you must consume or store everything) and Customer Grid-Supply Plus (export at avoided-cost rates, roughly $0.10–$0.14/kWh — much less than the $0.35+ retail rate you pay). Both heavily favor battery-first system design.
Stack the federal 26% credit with Hawaii's 35% RETITC (capped at $5,000) and you're routinely looking at 50%+ of system cost back at tax time on a $15K residential install.
Incentive snapshot
As of mid-2026. Verify on your state's energy website before relying on the dollar figures.
- Federal Residential Clean Energy Credit
- 26%
- State tax credit
- up to $5,000
- Sales tax exemption on solar equipment
- No
- Property tax exemption
- Yes
- Net metering
- Limited / restructured
- SREC market
- None
- Average peak sun hours
- 5.8 hrs/day
- DIY-permit friendly
- Yes
Phases down: 30% through 2025 → 26% in 2026 → 22% in 2027 → 0% under current law. Dwellings only — vehicle/RV systems don't qualify.
35% of system cost, capped at $5,000 per system (Hawaii Renewable Energy Technologies Income Tax Credit, aka RETITC).
Equipment is taxed at standard sales tax rate.
Adding solar doesn't bump your assessed value.
HECO closed traditional net metering in 2015. Current options — Customer Self-Supply (no export) and Customer Grid-Supply Plus (export at avoided-cost rate, ~$0.10–$0.14/kWh) — heavily favor battery-first systems.
No SREC revenue available in this state.
Used to size your array — more sun hours = fewer panels needed for the same output.
Honolulu permits can take 6+ months. Neighbor islands move faster. Salt-air corrosion within ~1 mile of coast — spec marine-grade hardware and IP65+ enclosures.
DIY install angle in Hawaii
Hawaii does allow homeowner permits, but the timeline is the story. Honolulu permits regularly take 6+ months; neighbor islands (Maui, Kauai, Big Island) typically move in a few weeks. Plan the build sequence accordingly — you can buy and stage equipment while the permit clears, but don't energize before approval.
Salt air is the unique enemy. Within roughly a mile of the coast, standard galvanized hardware corrodes within a few years. Spec marine-grade stainless fasteners, IP65+ enclosures for charge controllers, and either powder-coated or anodized aluminum racking. Renogy, Victron, and EG4 enclosures generally pass; cheaper imports often don't.
Off-grid is increasingly competitive in HI given how unfavorable the grid-supply economics have become. A fully off-grid setup with adequate battery skips the utility approval process entirely and locks in the full $0.35+/kWh value of every kWh you generate.
Sizing for Hawaii sun
Hawaii averages 5.8 peak sun hours/day across the islands, with high consistency year-round (no big winter drop-off like mainland states). That makes sizing simpler — you can design for the average and not lose much in any season.
Trade winds moderate temperature, so panels run cooler than you'd expect for the latitude. Real-world output often beats nameplate-derated estimates by 5–10%.
For a typical 8 kWh/day Hawaii household load (lower than mainland because heating isn't needed and AC use is moderate near the coast), expect roughly 2 kW of panels and 15 kWh of LFP battery for a comfortable battery-first system.
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