Solar panels in Urban Honolulu: what they cost and what they make
A typical Urban Honolulu home needs 9 solar panels. They would make about 6,296 kWh a year and cost $9,500 to $14k before incentives. At today's electricity prices they pay for themselves in about 6.6 yrs.
See panels on your own Urban Honolulu roof
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What solar costs in Urban Honolulu
At $3.00 a watt, the median price cash buyers pay nationally, a 3.8 kW system costs about $11,400. Quotes in Urban Honolulu will usually fall between $9,500 and $14,250. Complex roofs, main-panel upgrades and financing push prices up.
The 30% federal tax credit no longer applies to systems homeowners buy. This estimate includes no state or utility incentives; check with your utility before you buy.
The number that decides whether solar pays in Urban Honolulu is what your utility pays for the power you send back. Hawaii closed retail net metering to new customers in 2015; current programs credit exports well below retail. Under full payback is about 3.9 yrs. Under net billing it is about 6.6 yrs, because only the ~41% of solar a typical home uses as it is made saves the full retail price.
Cash purchase, prices rising 2.5% a year, panels losing 0.5% a year, $25/kW a year for upkeep. No federal credit for homeowner-owned systems.
Every way to pay for a 3.8 kW system in Urban Honolulu
Change any number →| Way to pay | Day one | Monthly payment | Monthly net, year 1 | Ahead after 25 years |
|---|---|---|---|---|
| Pay cash Full price on install day | $11,400 | $0 | +$135 | $41k |
| Credit-union loan 8% APR, 20 years, no dealer fee | $0 | $95 | +$39 | $29k |
| “1.99%” solar loan 1.99% APR, 25 years, 25% dealer fee | $0 | $60 | +$74 | $34k |
| Lease $120/mo, +2.9%/yr | $0 | $120 | +$23 | $2,900 |
| Power purchase (PPA) 23.1¢/kWh, +2.9%/yr | $0 | $121 | +$21 | $5,700 |
Under net billing, the usual rule for new customers here, at 46.3¢/kWh rising 2.5% a year. The “1.99%” loan’s $2,850 dealer fee is included in its payments. Lease and PPA prices are typical offers, not quotes.
How much sunshine Urban Honolulu gets
kWh per kW, 25° southAug is the best month for solar in Urban Honolulu, and Feb the weakest: a Feb day makes 85% of a Aug day. A 6 kW system would make about 757 kWh in Feb and 892 kWh in Aug.
On June 21 the sun rises at 5:50 am and sets at 7:16 pm, 13 hours 26 minutes of daylight. On December 21 it is up from 7:04 am to 5:54 pm, just 10 hours 50 minutes.
Peak sun hours in Urban Honolulu, month by month
| Month | Flat ground | Panels at 18° | kWh per kW |
|---|---|---|---|
| Jan | 4.3 | 5.3 | 134 |
| Feb | 4.9 | 5.6 | 126 |
| Mar | 5.6 | 5.9 | 142 |
| Apr | 6.4 | 6.3 | 142 |
| May | 6.9 | 6.4 | 144 |
| Jun | 7.1 | 6.4 | 138 |
| Jul | 7.0 | 6.4 | 144 |
| Aug | 6.8 | 6.5 | 149 |
| Sep | 6.3 | 6.5 | 149 |
| Oct | 5.2 | 5.9 | 143 |
| Nov | 4.4 | 5.3 | 129 |
| Dec | 4.0 | 5.0 | 127 |
| Year | 5.7 | 6.0 | 1,666 |
A peak sun hour is one hour of sunlight at 1,000 W per m². Why sites disagree.
The best angle and direction for panels in Urban Honolulu
| Roof faces (6/12 pitch) | Output vs south | kWh per kW |
|---|---|---|
| South | 100% | 1,666 |
| Southeast | 98% | 1,633 |
| Southwest | 98% | 1,633 |
| East | 91% | 1,516 |
| West | 91% | 1,516 |
| North | 77% | 1,283 |
Face panels south and tilt them 18° for the most energy over a year. East and west roofs keep about 91% of that. A north-facing roof keeps 77%, which can still be worth pricing this far south. Try other angles.
Where the sun goes over Urban Honolulu
The noon sun is lower in winter, which is why the best winter tilt (45°) is steeper than the best summer tilt (0°).
Urban Honolulu's homes
Urban Honolulu has 136,902 households. 48.9% own their home, and 34,014 of those owners live in single-family houses, the kind of home that usually gets rooftop solar.
The median home here was built in 1974. Many roofs that age are due for replacement. Replace the roof first, then add solar: taking panels off and putting them back later costs thousands.
49.1% of homes heat with electricity and 5.2% with gas. If you switch to a heat pump or an electric car, plan for more panels or leave room on the roof.
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates.
If the power goes out in Urban Honolulu
Solar panels alone shut off in a blackout. Add a battery and they keep going. One Tesla Powerwall 3 (13.5 kWh) running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day):
Change the appliances, the battery and the weather in the battery calculator.
Questions people ask about solar in Urban Honolulu
How much do solar panels cost in Urban Honolulu?
A 3.8 kW system — enough for the average Hawaii home — costs about $9,500 to $14,250 before incentives, based on $2.50–$3.75 per watt. The 30% federal credit no longer applies to systems homeowners buy.
How many solar panels does a house in Urban Honolulu need?
About 9 panels of 420 watts for a home using 495 kWh a month, the Hawaii average. Each kilowatt of panels here makes about 1,666 kWh a year on a south-facing roof.
Is solar worth it in Urban Honolulu?
Over 25 years, solar power here costs about 9.2¢ per kWh, against 46.3¢ from the grid today. Payback is about 3.9 yrs if your utility credits exported power at the full retail rate, and 6.6 yrs if it pays about 30% of retail. Most new customers in Hawaii are on the lower rate.
How many peak sun hours does Urban Honolulu get?
6.0 a day on panels tilted to 18°, and 5.7 on flat ground. The best month is Sep; the weakest is Dec.
What is the best angle for solar panels in Urban Honolulu?
18° for the most energy over a year, facing south. 45° is best in winter and 0° in summer. On a normal pitched roof, anything within 15° of 18° gives you about 95% of the maximum.
How long would a home battery last in a Urban Honolulu power outage?
A Tesla Powerwall 3 running a fridge, freezer, furnace fan, lights, Wi-Fi, TV and microwave (6.9 kWh a day) lasts about 43 hours with no sun. With 7 kW of solar to recharge it, it gets through a three-day outage even in overcast January.
Solar near Urban Honolulu
| City | Miles | kWh per kW | Sun hours |
|---|---|---|---|
| Honolulu, HI | 0 | 1,676 | 6.0 |
| San Francisco, CA | 2,359 | 1,540 | 5.3 |
| Daly City, CA | 2,388 | 1,600 | 5.6 |
| Petaluma, CA | 2,392 | 1,628 | 5.7 |
| South San Francisco, CA | 2,392 | 1,606 | 5.6 |
Urban Honolulu shares a weather-data neighbourhood with Honolulu; their sunshine numbers differ by less than our data can resolve. Housing, prices and outage figures are specific to Urban Honolulu.
Cities with the same sunshine as Urban Honolulu
These far-away cities get almost exactly as much solar energy per panel.
- Stockton, CA 1,677 kWh per kW
- Reno, NV 1,680 kWh per kW
- Grand Junction, CO 1,681 kWh per kW
Sources: NASA POWER 2001–2020 monthly climatology (grid cell 41 km from Urban Honolulu's Census point), our PV model (within 1.6% of NLR PVWatts® on average), U.S. EIA prices and use, U.S. Census 2025 population estimates and ACS 2020–2024. Estimates for an average home, not a site survey. How we calculate.