Peak Sun Hours in San Antonio, Texas, United States
- Solar zone
- Zone 3 (good)
- Best month
- July (6.7)
- Worst month
- December (2.8)
- Climate
- Temperate · 20.5°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 3.08 | 4.26 | 4.35 | 1.09 | 10.1 | 70 |
| Feb | 3.61 | 5.23 | 4.24 | 1.34 | 12.4 | 70 |
| Mar | 4.53 | 6.38 | 4.44 | 1.71 | 16.8 | 70 |
| Apr | 5.37 | 7.29 | 4.63 | 2.09 | 21.1 | 66 |
| May | 5.85 | 7.68 | 4.55 | 2.36 | 24.9 | 68 |
| Jun | 6.67 | 7.96 | 5.63 | 2.42 | 28.2 | 65 |
| Jul | 6.69 | 7.78 | 5.65 | 2.38 | 28.9 | 65 |
| Aug | 6.43 | 7.29 | 5.87 | 2.16 | 29.6 | 61 |
| Sep | 5.21 | 6.42 | 4.75 | 2.03 | 26.0 | 68 |
| Oct | 4.42 | 5.43 | 5.32 | 1.40 | 21.3 | 68 |
| Nov | 3.32 | 4.39 | 4.48 | 1.16 | 15.7 | 70 |
| Dec | 2.80 | 3.92 | 4.10 | 1.03 | 11.1 | 69 |
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 2.80 kWh/m²/day, 0.77 system efficiency.
About solar in San Antonio
San Antonio, United States has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 4.83 kWh/m²/day, a good solar resource by global standards.
The strongest month in San Antonio is July (summer) at 6.69 kWh/m²/day, and the weakest is December (winter) at 2.8 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.
San Antonio'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 San Antonio?
- San Antonio averages 4.83 peak sun hours per day annually, ranging from 2.8 in December to 6.69 in July.
- How many solar panels do I need in San Antonio?
- Panel count depends on your daily load. At San Antonio's annual average of 4.83 kWh/m²/day, a 5 kWh/day load needs roughly 4 × 400 W panels. Use the calculator above for your actual load.
- What size battery do I need in San Antonio?
- Sizing against San Antonio's worst month (December, 2.8 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 San Antonio's solar resource compare globally?
- San Antonio sits in solar zone 3 out of 5 (where 5 is strongest) at 4.83 kWh/m²/day — good 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 San Antonio?
- San Antonio's worst month (December) delivers 2.8 kWh/m²/day — about 42% of the summer peak of 6.69. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect San Antonio's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. San Antonio's 4.83 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in San Antonio?
- At San Antonio's latitude (29°), a fixed tilt near 29° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.