25-year savings projection for Hawaii
This projection starts from Hawaii's assumed $0.42/kWh electricity rate and 1,580 kWh/kW of annual production, then grows savings by 3% a year as electricity prices rise and reduces output by 0.5% a year as panels degrade.
| Year | Annual savings | Cumulative savings | vs. $27,200 cost |
|---|---|---|---|
| Year 1 | $4,374 | $4,374 | −$22,826 |
| Year 5 | $4,826 | $22,987 | −$4,213 |
| Year 10 | $5,456 | $48,975 | +$21,775 |
| Year 15 | $6,168 | $78,357 | +$51,157 |
| Year 20 | $6,974 | $111,575 | +$84,375 |
| Year 25 | $7,884 | $149,132 | +$121,932 |
A simple, undiscounted projection — it does not apply a discount rate, financing interest, inverter replacement (commonly needed once in 25 years), maintenance, or any change in home value. Treat it as a shape, not a forecast. See methodology.
Why savings look like this in Hawaii
The highest electricity prices in the country make solar-plus-battery compelling despite the end of classic net metering.
The single biggest variable is what your utility pays for exported power. Hawaii ended traditional net metering in 2015. Current options such as Smart Export and the Battery Bonus successor programs favor battery storage and limit or time-restrict grid exports.
What would change this number
- Your actual rate. This uses a $0.42/kWh Hawaii average. If you pay more, savings scale up roughly proportionally.
- Self-consumption. We assume 68% of output is used on site at retail value and the rest exported at 45% of retail. Households home during the day, or with a battery, do better.
- Electricity price growth. At 3% a year, savings nearly double by year 25. Slower growth meaningfully reduces lifetime return.
- Incentives. Hawaii's main program — 35% state tax credit (capped at $5,000) — reduces net cost and shortens break-even. See Hawaii incentives →
- Financing. A cash purchase earns the return above. A loan shifts it — interest can consume a large share of lifetime savings.
Frequently asked questions
How much can you save with solar panels in Hawaii?
An 8 kW system in Hawaii could save roughly $4,374 in the first year — about $365 a month — and around $149,132 across 25 years, assuming electricity prices rise 3% a year and panel output declines 0.5% a year. Against a midpoint installed cost of $27,200, that is a net gain of about $121,932.
What is the ROI on solar panels in Hawaii?
On these assumptions, roughly 448% over a 25-year system life — $121,932 of net savings on a $27,200 system. That is a simple, undiscounted return: it ignores financing interest, the time value of money, and any effect on home resale value. A cash purchase and a loan produce very different numbers.
How long does it take for solar to pay for itself in Hawaii?
Around year 6, when cumulative savings first exceed the $27,200 installed cost. A simple payback that ignores rising electricity prices gives a wider range of 5–7 years.
Do solar savings in Hawaii include the federal tax credit?
No. The 30% federal residential clean energy credit (Section 25D) ended for systems installed after December 31, 2025, so none of these figures include it. Any savings projection you see elsewhere that still applies 30% to a 2026 purchase is overstating the return.
What most affects solar savings in Hawaii?
Three things, in order: your utility's export compensation (Hawaii ended traditional net metering in 2015.), how much of the output your household consumes on site rather than exporting, and your actual electricity rate versus the 0.42/kWh state assumption used here. 35% state tax credit (capped at $5,000) can improve the result further.
Where these numbers come from
State assumptions are informed by public data and reviewed periodically (September 2026):