Peak Sun Hours in Belfast, Northern Ireland, United Kingdom
- Solar zone
- Zone 1 (modest)
- Best month
- June (5.1)
- Worst month
- December (0.4)
- Climate
- Continental · 9.8°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 0.57 | 1.05 | 1.07 | 0.36 | 5.8 | 91 |
| Feb | 1.26 | 2.15 | 1.93 | 0.71 | 5.5 | 90 |
| Mar | 2.47 | 3.88 | 2.85 | 1.32 | 6.2 | 88 |
| Apr | 3.93 | 5.85 | 3.81 | 1.95 | 8.0 | 86 |
| May | 5.02 | 7.42 | 4.53 | 2.36 | 10.5 | 85 |
| Jun | 5.11 | 8.03 | 4.05 | 2.59 | 13.1 | 85 |
| Jul | 4.82 | 7.60 | 3.65 | 2.54 | 14.5 | 86 |
| Aug | 3.97 | 6.26 | 3.30 | 2.14 | 14.5 | 87 |
| Sep | 2.80 | 4.44 | 2.79 | 1.56 | 13.3 | 88 |
| Oct | 1.55 | 2.61 | 2.00 | 0.88 | 11.1 | 88 |
| Nov | 0.73 | 1.30 | 1.31 | 0.44 | 8.4 | 90 |
| Dec | 0.42 | 0.77 | 0.90 | 0.28 | 6.6 | 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 0.42 kWh/m²/day, 0.77 system efficiency.
About solar in Belfast
Belfast, United Kingdom has a continental climate with cold winters and warmer summers. Its annual peak sun hours average 2.72 kWh/m²/day, a modest solar resource by global standards.
The strongest month in Belfast is June (summer) at 5.11 kWh/m²/day, and the weakest is December (winter) at 0.42 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 modest resource, Belfast installations typically oversize panels or combine solar with another source (grid, generator, hydro) for reliability.
FAQ
- What are the peak sun hours in Belfast?
- Belfast averages 2.72 peak sun hours per day annually, ranging from 0.42 in December to 5.11 in June.
- How many solar panels do I need in Belfast?
- Panel count depends on your daily load. At Belfast's annual average of 2.72 kWh/m²/day, a 5 kWh/day load needs roughly 6 × 400 W panels. Use the calculator above for your actual load.
- What size battery do I need in Belfast?
- Sizing against Belfast's worst month (December, 0.42 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 Belfast's solar resource compare globally?
- Belfast sits in solar zone 1 out of 5 (where 5 is strongest) at 2.72 kWh/m²/day — modest by global standards. For reference, top-tier desert sites average ~6.5 and high-latitude cities around 2.5 kWh/m²/day.
- Does snow block solar panels in Belfast?
- Yes — snow cover can drop output to near zero. In Belfast's winter months (around December), brush panels after significant snowfall or design with steep tilt (45°+) so snow slides off naturally.
- How much does winter hurt solar output in Belfast?
- Belfast's worst month is December at 0.42 kWh/m²/day versus 5.11 in June — a 172% seasonal swing. Off-grid continental systems usually combine oversized arrays with wood-stove or generator backup.
- Is solar worth it in a continental climate like Belfast's?
- Yes, but the seasonal ratio matters. Belfast's annual 2.72 kWh/m²/day is solid; grid-tied net metering works well (summer credits offset winter draw). Full off-grid needs generator or hydro backup.