Peak Sun Hours in Saint-Étienne, Rhône-Alpes, France
- Solar zone
- Zone 2 (moderate)
- Best month
- July (6.4)
- Worst month
- December (1.1)
- Climate
- Temperate · 10.2°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 1.33 | 2.23 | 2.27 | 0.69 | 1.1 | 91 |
| Feb | 2.19 | 3.41 | 3.06 | 1.05 | 1.6 | 87 |
| Mar | 3.51 | 5.00 | 3.81 | 1.61 | 5.2 | 82 |
| Apr | 4.72 | 6.61 | 4.47 | 2.05 | 9.1 | 77 |
| May | 5.45 | 7.79 | 4.39 | 2.53 | 13.0 | 75 |
| Jun | 6.40 | 8.26 | 5.59 | 2.61 | 17.9 | 69 |
| Jul | 6.42 | 7.95 | 6.10 | 2.35 | 20.4 | 61 |
| Aug | 5.49 | 6.90 | 5.51 | 2.06 | 19.8 | 62 |
| Sep | 4.15 | 5.41 | 4.69 | 1.67 | 15.3 | 69 |
| Oct | 2.59 | 3.76 | 3.33 | 1.21 | 11.0 | 80 |
| Nov | 1.50 | 2.46 | 2.36 | 0.78 | 5.5 | 89 |
| Dec | 1.11 | 1.88 | 2.16 | 0.57 | 1.9 | 91 |
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 1.11 kWh/m²/day, 0.77 system efficiency.
About solar in Saint-Étienne
Saint-Étienne, France has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 3.74 kWh/m²/day, a moderate solar resource by global standards.
The strongest month in Saint-Étienne is July (summer) at 6.42 kWh/m²/day, and the weakest is December (winter) at 1.11 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.
Given the moderate resource, Saint-Étienne installations typically oversize panels or combine solar with another source (grid, generator, hydro) for reliability.
FAQ
- What are the peak sun hours in Saint-Étienne?
- Saint-Étienne averages 3.74 peak sun hours per day annually, ranging from 1.11 in December to 6.42 in July.
- How many solar panels do I need in Saint-Étienne?
- Panel count depends on your daily load. At Saint-Étienne's annual average of 3.74 kWh/m²/day, a 5 kWh/day load needs roughly 5 × 400 W panels. Use the calculator above for your actual load.
- What size battery do I need in Saint-Étienne?
- Sizing against Saint-Étienne's worst month (December, 1.11 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 Saint-Étienne's solar resource compare globally?
- Saint-Étienne sits in solar zone 2 out of 5 (where 5 is strongest) at 3.74 kWh/m²/day — moderate 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 Saint-Étienne?
- Saint-Étienne's worst month (December) delivers 1.11 kWh/m²/day — about 17% of the summer peak of 6.42. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect Saint-Étienne's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. Saint-Étienne's 3.74 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in Saint-Étienne?
- At Saint-Étienne's latitude (45°), a fixed tilt near 45° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.