Peak Sun Hours in Tucson, Arizona, United States
- Solar zone
- Zone 4 (excellent)
- Best month
- June (8.3)
- Worst month
- December (3.3)
- Climate
- Temperate · 17.7°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 3.56 | 4.16 | 6.14 | 0.98 | 7.7 | 49 |
| Feb | 4.49 | 5.29 | 6.60 | 1.25 | 9.2 | 46 |
| Mar | 5.97 | 6.71 | 7.80 | 1.46 | 12.9 | 39 |
| Apr | 7.37 | 7.97 | 9.07 | 1.53 | 16.6 | 30 |
| May | 8.18 | 8.71 | 9.75 | 1.57 | 21.5 | 24 |
| Jun | 8.32 | 8.82 | 9.85 | 1.50 | 27.5 | 20 |
| Jul | 6.91 | 8.21 | 6.54 | 2.15 | 27.4 | 45 |
| Aug | 6.51 | 7.59 | 6.72 | 1.86 | 26.7 | 49 |
| Sep | 5.90 | 6.69 | 7.31 | 1.41 | 24.2 | 46 |
| Oct | 5.11 | 5.55 | 7.76 | 1.04 | 18.8 | 41 |
| Nov | 3.93 | 4.39 | 6.76 | 0.93 | 12.6 | 42 |
| Dec | 3.25 | 3.81 | 5.84 | 0.92 | 7.4 | 50 |
GHI, Clear-sky, DNI, DHI in kWh/m²/day. Data: NASA POWER climatology (long-term monthly averages).
Off-grid calculator
Add appliances
- Add an appliance to size a system.
Sizing
- Daily load
- 0.00 kWh
- Panel wattage
- 0 W
- Panel count (400W modules)
- 0
- Battery bank
- 0.0 kWh
Sizing against worst-month PSH of 3.25 kWh/m²/day, 0.77 system efficiency.
About solar in Tucson
Tucson, United States has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 5.79 kWh/m²/day, a excellent solar resource by global standards.
The strongest month in Tucson is June (summer) at 8.32 kWh/m²/day, and the weakest is December (winter) at 3.25 kWh/m²/day. When sizing a year-round off-grid system, it's standard practice to design against the December value rather than the annual average — otherwise the battery bank runs low during the darkest weeks.
Tucson's solar conditions are well within the range where off-grid PV is a straightforward engineering exercise with standard-sized arrays and lithium batteries.
FAQ
- What are the peak sun hours in Tucson?
- Tucson averages 5.79 peak sun hours per day annually, ranging from 3.25 in December to 8.32 in June.
- How many solar panels do I need in Tucson?
- Panel count depends on your daily load. At Tucson's annual average of 5.79 kWh/m²/day, a 5 kWh/day load needs roughly 3 × 400 W panels. Use the calculator above for your actual load.
- What size battery do I need in Tucson?
- Sizing against Tucson's worst month (December, 3.25 kWh/m²/day) with 2 days of autonomy at 80% depth of discharge, a 5 kWh/day load needs about a 12.5 kWh battery bank.
- How does Tucson's solar resource compare globally?
- Tucson sits in solar zone 4 out of 5 (where 5 is strongest) at 5.79 kWh/m²/day — excellent by global standards. For reference, top-tier desert sites average ~6.5 and high-latitude cities around 2.5 kWh/m²/day.
- How much does winter reduce solar output in Tucson?
- Tucson's worst month (December) delivers 3.25 kWh/m²/day — about 39% of the summer peak of 8.32. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect Tucson's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. Tucson's 5.79 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in Tucson?
- At Tucson's latitude (32°), a fixed tilt near 32° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.