Peak Sun Hours in Donostia / San Sebastián, Basque Country, Spain
- Solar zone
- Zone 2 (moderate)
- Best month
- June (6.0)
- Worst month
- December (1.3)
- Climate
- Temperate · 14.4°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 1.43 | 2.44 | 2.17 | 0.77 | 9.2 | 83 |
| Feb | 2.32 | 3.59 | 3.04 | 1.12 | 8.9 | 81 |
| Mar | 3.56 | 5.17 | 3.55 | 1.72 | 10.7 | 80 |
| Apr | 4.60 | 6.71 | 3.83 | 2.23 | 12.5 | 80 |
| May | 5.45 | 7.81 | 4.23 | 2.58 | 15.0 | 81 |
| Jun | 5.96 | 8.17 | 4.65 | 2.68 | 18.3 | 80 |
| Jul | 5.95 | 7.90 | 4.83 | 2.62 | 20.1 | 79 |
| Aug | 5.28 | 6.93 | 4.67 | 2.30 | 20.8 | 77 |
| Sep | 4.31 | 5.52 | 4.46 | 1.85 | 19.1 | 76 |
| Oct | 2.77 | 3.97 | 3.38 | 1.30 | 16.5 | 77 |
| Nov | 1.69 | 2.69 | 2.53 | 0.85 | 12.3 | 81 |
| Dec | 1.31 | 2.11 | 2.26 | 0.67 | 9.9 | 82 |
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 1.31 kWh/m²/day, 0.77 system efficiency.
About solar in Donostia / San Sebastián
Donostia / San Sebastián, Spain has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 3.72 kWh/m²/day, a moderate solar resource by global standards.
The strongest month in Donostia / San Sebastián is June (summer) at 5.96 kWh/m²/day, and the weakest is December (winter) at 1.31 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, Donostia / San Sebastián installations typically oversize panels or combine solar with another source (grid, generator, hydro) for reliability.
FAQ
- What are the peak sun hours in Donostia / San Sebastián?
- Donostia / San Sebastián averages 3.72 peak sun hours per day annually, ranging from 1.31 in December to 5.96 in June.
- How many solar panels do I need in Donostia / San Sebastián?
- Panel count depends on your daily load. At Donostia / San Sebastián's annual average of 3.72 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 Donostia / San Sebastián?
- Sizing against Donostia / San Sebastián's worst month (December, 1.31 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 Donostia / San Sebastián's solar resource compare globally?
- Donostia / San Sebastián sits in solar zone 2 out of 5 (where 5 is strongest) at 3.72 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 Donostia / San Sebastián?
- Donostia / San Sebastián's worst month (December) delivers 1.31 kWh/m²/day — about 22% of the summer peak of 5.96. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect Donostia / San Sebastián's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. Donostia / San Sebastián's 3.72 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in Donostia / San Sebastián?
- At Donostia / San Sebastián's latitude (43°), a fixed tilt near 43° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.