Peak Sun Hours in Hạ Long, Quảng Ninh, Vietnam
- Solar zone
- Zone 3 (good)
- Best month
- June (5.3)
- Worst month
- January (2.5)
- Climate
- Tropical · 23.3°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 2.48 | 4.56 | 1.44 | 1.54 | 15.8 | 79 |
| Feb | 2.79 | 5.18 | 1.26 | 1.80 | 17.7 | 81 |
| Mar | 2.99 | 5.56 | 0.96 | 2.03 | 20.5 | 82 |
| Apr | 4.20 | 6.33 | 1.88 | 2.50 | 24.0 | 82 |
| May | 5.23 | 7.09 | 3.32 | 2.65 | 26.9 | 84 |
| Jun | 5.28 | 7.30 | 3.27 | 2.86 | 28.2 | 86 |
| Jul | 5.22 | 7.34 | 3.50 | 2.64 | 28.3 | 86 |
| Aug | 4.76 | 7.04 | 2.97 | 2.48 | 28.0 | 86 |
| Sep | 4.66 | 6.42 | 3.05 | 2.38 | 27.1 | 83 |
| Oct | 4.26 | 5.43 | 3.05 | 2.08 | 24.5 | 80 |
| Nov | 3.53 | 4.77 | 2.90 | 1.72 | 21.1 | 79 |
| Dec | 2.74 | 4.25 | 2.00 | 1.53 | 16.9 | 76 |
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 2.48 kWh/m²/day, 0.77 system efficiency.
About solar in Hạ Long
Hạ Long, Vietnam has a warm, tropical climate with a distinct wet and dry season. Its annual peak sun hours average 4.01 kWh/m²/day, a good solar resource by global standards.
The strongest month in Hạ Long is June (summer) at 5.28 kWh/m²/day, and the weakest is January (winter) at 2.48 kWh/m²/day. When sizing a year-round off-grid system, it's standard practice to design against the January value rather than the annual average — otherwise the battery bank runs low during the darkest weeks.
Hạ Long'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 Hạ Long?
- Hạ Long averages 4.01 peak sun hours per day annually, ranging from 2.48 in January to 5.28 in June.
- How many solar panels do I need in Hạ Long?
- Panel count depends on your daily load. At Hạ Long's annual average of 4.01 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 Hạ Long?
- Sizing against Hạ Long's worst month (January, 2.48 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 Hạ Long's solar resource compare globally?
- Hạ Long sits in solar zone 3 out of 5 (where 5 is strongest) at 4.01 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 does the wet season affect solar generation in Hạ Long?
- Hạ Long's dry-season output peaks at 5.28 kWh/m²/day in June; the wet season drops it to 2.48 in January. That ~70% swing is a key sizing consideration.
- Can solar panels survive tropical storms in Hạ Long?
- Most tier-1 PV panels are rated for 140+ mph wind loads; mounting hardware usually fails first. In cyclone-prone regions like Vietnam, specify IEC 61215-certified panels and anchor-bolt mounts rather than ballasted.
- What's the dry-to-wet output gap in Hạ Long?
- Hạ Long swings from 5.28 kWh/m²/day in June (dry) to 2.48 in January (wet) — roughly 70%. Year-round off-grid systems must size against the wet-season minimum.