Solar panels in Honolulu, HI
Roofs in Honolulu get about 1,787 hours of usable sunlight a year — more than 81% of the cities we've measured. Here's what that means in cost, savings and payback, using real rooftop data rather than a national average.
Check your specific roof in Honolulu → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Honolulu solar system costs
A 18-panel system (7.2 kW) is about right for an average Honolulu home using 10,800 kWh a year. It would produce roughly 10,936 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 4,861 | $6,384 | $2,046 | 3.1 yrs |
| 12 panels | 4.8 kW | 7,291 | $9,576 | $3,069 | 3.1 yrs |
| 16 panels | 6.4 kW | 9,721 | $12,768 | $4,093 | 3.1 yrs |
| 20 panels | 8 kW | 12,152 | $15,960 | $4,689 | 3.4 yrs |
| 26 panels | 10.4 kW | 15,797 | $20,748 | $5,073 | 4.1 yrs |
How we worked this out for Honolulu
Every number on this page comes from these seven steps. Nothing is a national average — the sunlight figure is measured from Honolulu rooftops.
| # | Step | Result |
|---|---|---|
| 1 | What one panel makes here 400W ÷ 1000 × 1,787 sun hrs × 0.85 system losses |
608 kWh/yr |
| 2 | Panels needed to cover typical usage 10,800 kWh ÷ 608 kWh per panel |
18 panels |
| 3 | System size 18 panels × 400W |
7.20 kW |
| 4 | Annual production 7.20 kW × 1,787 hrs × 0.85 |
10,936 kWh/yr |
| 5 | Installed cost 7,200 W × $2.85 per watt, then −30% federal credit |
$14,364 |
| 6 | Annual saving 3,780 kWh used as generated × 42.1¢ + 7,156 kWh exported × 42.1¢ |
$4,561/yr |
| 7 | Payback $14,364 ÷ $4,561 per year |
3.1 years |
Step 6 matters more than it looks. Only 35% of what a system this size produces in Honolulu is used the moment it is generated; the other 7,156 kWh is exported and credited one-for-one under net metering. Because exports here are credited at or near retail, that split changes the payback very little — 3.1 years against the 3.1 we show. In places where exports pay a fraction of retail the same split moves payback by years, which is why we model it explicitly rather than assuming.
Assumptions: 400W panels, 15% system losses (inverter, wiring, heat, soiling), $2.85/W installed, 10,800 kWh typical annual household use, 42.1¢/kWh electricity. Change any of those and every figure above moves — which is exactly why a single national "solar costs X" number is misleading.
Notice that payback barely improves as systems get bigger, and eventually gets worse. That's because you can only save money on electricity you were going to buy anyway. Once a system covers your usage, extra panels mostly generate exports at a much lower rate.
Why Honolulu gets 1,787 sun hours
That figure comes from Google's analysis of real rooftops across Honolulu — it already accounts for shading from trees, chimneys and neighbouring buildings, which is why it's lower than the raw "hours of daylight" figures you'll see elsewhere. An unusually open, unshaded roof in Honolulu reaches about 1,925 hours, roughly 8% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,787 hrs/yr |
|---|---|
| Unshaded roof | 1,925 hrs/yr |
| Electricity rate (Hawaii avg) | 42.1¢/kWh |
| Installed cost assumed | $2.85/W |
| Panel size assumed | 400 W |
| Federal tax credit | 30% |
| Typical household usage | 10,800 kWh/yr |
| Power used as generated | 35% |
| Paid for exported power | full retail (net metering) |
| Rooftops sampled here | 7 |
| Google imagery from | 2019 |
When Honolulu actually produces
Annual totals hide the thing that catches people out: 29% of Honolulu's yearly sunlight arrives in May–July, and just 19% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 116 | |
| Feb | 133 | |
| Mar | 152 | |
| Apr | 167 | |
| May | 174 | |
| Jun | 176 | |
| Jul | 174 | |
| Aug | 169 | |
| Sep | 157 | |
| Oct | 138 | |
| Nov | 120 | |
| Dec | 111 |
Output is unusually steady — only about 1.6× between Jun and Dec. Honolulu is close enough to the equator that seasonal variation is mild, which makes sizing a system considerably more predictable.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Honolulu's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Honolulu compares to the other 788 cities
| Measure | Honolulu | Rank of 788 |
|---|---|---|
| Usable sunlight | 1,787 hrs | 148th |
| Sunlight lost to shade | 7% | 200th most |
| Median roof size | 262 m² | 187th largest |
| Electricity rate | 42.1¢ | 1st highest |
| Payback | 3.1 yrs | 1st fastest |
| Grid carbon | 748 kg/MWh | 205th dirtiest |
What actually stands out about Honolulu:
- Sunnier than the rest of Hawaii. Honolulu roofs get 10% more usable sunlight than the typical Hawaii city we've measured — statewide averages will understate what you can expect here.
- Expensive electricity works in your favour. At 42.1¢/kWh, Hawaii is among the priciest places to buy power — which is exactly what makes generating your own pay back faster.
- Older imagery. Google's aerial capture of Honolulu dates from 2019. Tree growth and new construction since then are not reflected.
Cities with almost the same sunlight
These are the closest matches to Honolulu's 1,787 usable sun hours from other states and provinces. Same sunlight, different electricity prices — which is usually what decides whether solar is worth it.
| City | Sun hrs | Rate | Payback |
|---|---|---|---|
| Cheyenne, WY | 1,788 | 12.1¢ | 11 yrs |
| Flagstaff, AZ | 1,788 | 15.2¢ | 8.7 yrs |
| Palm Bay, FL | 1,789 | 15.3¢ | 8.7 yrs |
| Wichita, KS | 1,790 | 14.1¢ | 9.4 yrs |
Nearby cities
See all of Hawaii → statewide sunlight, rates, incentives and every city we've measured.
Honolulu solar questions
How many solar panels do I need in Honolulu?
About 18 panels for an average home using 10,800 kWh a year. Honolulu roofs get 1,787 usable sun hours, so each 400W panel produces roughly 608 kWh annually. A typical Honolulu roof fits about 71 panels, so roof space is unlikely to be your limit.
Is solar worth it in Honolulu?
At 42.1¢/kWh and 1,787 sun hours, a typical system pays for itself in about 3.1 years and returns roughly $99,665 over a 25-year panel life. That is a solid return, and it improves further if electricity prices rise. Exported power earns full retail credit here.
How much do solar panels cost in Honolulu?
A 7.2 kW system costs about $20,520 before incentives and $14,364 after the 30% federal tax credit. That works out near $2.85 per watt installed. Roof pitch, shading, electrical panel upgrades and equipment choice move the price most, which is why quotes for the same house can differ by thousands.
Worth reading before you buy
Estimates only, generated 2026-08-22 from Google Solar API rooftop samples and average Hawaii electricity rates. Not a quote and not financial advice. Your roof, usage, utility plan and local incentives will change these numbers — get real quotes before buying.