Peak Sun Hours in Houston, Texas, United States
- Solar zone
- Zone 3 (good)
- Best month
- June (6.3)
- Worst month
- December (2.6)
- Climate
- Temperate · 20.4°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 2.92 | 4.15 | 3.83 | 1.15 | 10.3 | 81 |
| Feb | 3.33 | 5.04 | 3.49 | 1.41 | 12.5 | 81 |
| Mar | 4.47 | 6.21 | 4.14 | 1.80 | 16.5 | 80 |
| Apr | 5.30 | 7.12 | 4.41 | 2.14 | 20.4 | 77 |
| May | 6.01 | 7.60 | 4.80 | 2.40 | 24.6 | 74 |
| Jun | 6.29 | 7.79 | 5.02 | 2.48 | 28.0 | 73 |
| Jul | 6.12 | 7.58 | 4.61 | 2.55 | 28.5 | 75 |
| Aug | 5.85 | 7.10 | 4.72 | 2.35 | 29.0 | 72 |
| Sep | 5.03 | 6.31 | 4.57 | 1.96 | 26.2 | 75 |
| Oct | 4.42 | 5.36 | 5.33 | 1.39 | 21.4 | 75 |
| Nov | 3.34 | 4.31 | 4.43 | 1.18 | 15.9 | 78 |
| Dec | 2.64 | 3.79 | 3.48 | 1.11 | 11.7 | 80 |
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 2.64 kWh/m²/day, 0.77 system efficiency.
About solar in Houston
Houston, United States has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 4.64 kWh/m²/day, a good solar resource by global standards.
The strongest month in Houston is June (summer) at 6.29 kWh/m²/day, and the weakest is December (winter) at 2.64 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.
Houston'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 Houston?
- Houston averages 4.64 peak sun hours per day annually, ranging from 2.64 in December to 6.29 in June.
- How many solar panels do I need in Houston?
- Panel count depends on your daily load. At Houston's annual average of 4.64 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 Houston?
- Sizing against Houston's worst month (December, 2.64 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 Houston's solar resource compare globally?
- Houston sits in solar zone 3 out of 5 (where 5 is strongest) at 4.64 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 Houston?
- Houston's worst month (December) delivers 2.64 kWh/m²/day — about 42% of the summer peak of 6.29. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect Houston's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. Houston's 4.64 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in Houston?
- At Houston's latitude (30°), a fixed tilt near 30° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.