Solar panels in Walla Walla, WA
Roofs in Walla Walla get about 1,459 hours of usable sunlight a year — less than 67% 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 Walla Walla → City averages are a starting point; your own roof's size, pitch and shading change the answer a lot.
What a typical Walla Walla solar system costs
A 22-panel system (8.8 kW) is about right for an average Walla Walla home using 10,800 kWh a year. It would produce roughly 10,913 kWh annually and offset 100% of that usage.
| System | Size | kWh/yr | Net cost | Saves/yr | Payback |
|---|---|---|---|---|---|
| 8 panels | 3.2 kW | 3,968 | $6,384 | $448 | 14.2 yrs |
| 12 panels | 4.8 kW | 5,953 | $9,576 | $673 | 14.2 yrs |
| 16 panels | 6.4 kW | 7,937 | $12,768 | $897 | 14.2 yrs |
| 20 panels | 8 kW | 9,921 | $15,960 | $1,121 | 14.2 yrs |
| 26 panels | 10.4 kW | 12,898 | $20,748 | $1,280 | 16.2 yrs |
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 Walla Walla gets 1,459 sun hours
That figure comes from Google's analysis of real rooftops across Walla Walla — 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 Walla Walla reaches about 1,563 hours, roughly 7% better than typical.
The numbers behind this page
| Typical usable sunlight | 1,459 hrs/yr |
|---|---|
| Unshaded roof | 1,563 hrs/yr |
| Electricity rate (Washington avg) | 11.3¢/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 | 6 |
| Google imagery from | 2019 |
When Walla Walla actually produces
Annual totals hide the thing that catches people out: 39% of Walla Walla's yearly sunlight arrives in May–July, and just 11% across November–January.
| Month | Sun hrs | Share of year |
|---|---|---|
| Jan | 54 | |
| Feb | 80 | |
| Mar | 115 | |
| Apr | 154 | |
| May | 183 | |
| Jun | 195 | |
| Jul | 189 | |
| Aug | 165 | |
| Sep | 129 | |
| Oct | 90 | |
| Nov | 60 | |
| Dec | 47 |
That is a severe seasonal swing — Walla Walla produces roughly 4.2× as much in Jun as in Dec. A system sized to cover your annual usage will overproduce badly in summer and fall well short in winter, so how your utility credits exported power matters more here than in most places.
The annual total is measured from Google's rooftop imagery. Its split across months is calculated from solar geometry at Walla Walla's latitude, not separately measured, so treat the monthly figures as the shape of a typical year rather than a forecast.
How Walla Walla compares to the other 673 cities
| Measure | Walla Walla | Rank of 673 |
|---|---|---|
| Usable sunlight | 1,459 hrs | 450th |
| Sunlight lost to shade | 7% | 216th most |
| Median roof size | 389 m² | 32nd largest |
| Electricity rate | 11.3¢ | 625th highest |
| Payback | 14.3 yrs | 589th fastest |
| Grid carbon | 696 kg/MWh | 278th dirtiest |
What actually stands out about Walla Walla:
- Plenty of roof to work with. Typical roofs here fit around 168 panels — roughly 7× what an average home needs. Roof size will not be what limits your system in Walla Walla.
- Large roofs. At a median of 389 m², Walla Walla has the 32nd-largest typical roof footprint we've measured.
- Sunnier than the rest of Washington. Walla Walla roofs get 17% more usable sunlight than the typical Washington city we've measured — statewide averages will understate what you can expect here.
- Cheap electricity is the headwind. Washington power costs about 11.3¢/kWh. Low rates are good news generally, but they lengthen solar payback — there is simply less bill to displace.
- Older imagery. Google's aerial capture of Walla Walla 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 Walla Walla's 1,459 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 |
|---|---|---|---|
| Detroit, MI | 1,459 | 19.1¢ | 8.5 yrs |
| Billings, MT | 1,459 | 12.1¢ | 13.4 yrs |
| Schaumburg, IL | 1,459 | 16.3¢ | 9.9 yrs |
| Terre Haute, IN | 1,459 | 15.3¢ | 10.6 yrs |
Nearby cities
See all of Washington → statewide sunlight, rates, incentives and every city we've measured.
Walla Walla solar questions
How many solar panels do I need in Walla Walla?
About 22 panels for an average home using 10,800 kWh a year. Walla Walla roofs get 1,459 usable sun hours, so each 400W panel produces roughly 496 kWh annually. A typical Walla Walla roof fits about 168 panels, so roof space is unlikely to be your limit.
Is solar worth it in Walla Walla?
At 11.3¢/kWh and 1,459 sun hours, a typical system pays for itself in about 14.3 years and returns roughly $13,034 over a 25-year panel life. That is slower than average, so compare several quotes before committing. Exported power earns full retail credit here.
How much do solar panels cost in Walla Walla?
A 8.8 kW system costs about $25,080 before incentives and $17,556 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 Washington 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.