Peak Sun Hours in Hamamatsu, Shizuoka, Japan
- Solar zone
- Zone 3 (good)
- Best month
- August (5.5)
- Worst month
- December (2.4)
- Climate
- Temperate · 17.8°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 2.70 | 3.56 | 4.02 | 1.07 | 8.9 | 75 |
| Feb | 3.35 | 4.54 | 4.00 | 1.38 | 9.5 | 73 |
| Mar | 4.26 | 5.77 | 4.10 | 1.76 | 11.7 | 73 |
| Apr | 4.95 | 6.85 | 3.89 | 2.19 | 15.5 | 75 |
| May | 5.34 | 7.57 | 3.66 | 2.52 | 19.1 | 80 |
| Jun | 4.84 | 7.64 | 2.57 | 2.67 | 22.3 | 85 |
| Jul | 5.28 | 7.43 | 3.42 | 2.56 | 25.6 | 88 |
| Aug | 5.55 | 6.88 | 4.56 | 2.26 | 27.2 | 85 |
| Sep | 4.29 | 5.98 | 3.72 | 1.87 | 25.2 | 80 |
| Oct | 3.30 | 4.80 | 3.42 | 1.42 | 21.1 | 75 |
| Nov | 2.73 | 3.70 | 3.65 | 1.11 | 16.6 | 73 |
| Dec | 2.43 | 3.21 | 3.85 | 0.96 | 11.6 | 74 |
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 2.43 kWh/m²/day, 0.77 system efficiency.
About solar in Hamamatsu
Hamamatsu, Japan has a temperate climate with meaningful seasonal variation in solar resource. Its annual peak sun hours average 4.09 kWh/m²/day, a good solar resource by global standards.
The strongest month in Hamamatsu is August (summer) at 5.55 kWh/m²/day, and the weakest is December (winter) at 2.43 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.
Hamamatsu'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 Hamamatsu?
- Hamamatsu averages 4.09 peak sun hours per day annually, ranging from 2.43 in December to 5.55 in August.
- How many solar panels do I need in Hamamatsu?
- Panel count depends on your daily load. At Hamamatsu's annual average of 4.09 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 Hamamatsu?
- Sizing against Hamamatsu's worst month (December, 2.43 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 Hamamatsu's solar resource compare globally?
- Hamamatsu sits in solar zone 3 out of 5 (where 5 is strongest) at 4.09 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 Hamamatsu?
- Hamamatsu's worst month (December) delivers 2.43 kWh/m²/day — about 44% of the summer peak of 5.55. Off-grid systems here typically oversize 1.5–2× or pair with a backup source.
- Do cloudy days significantly affect Hamamatsu's solar?
- Partly. Diffuse light still produces 10–25% of clear-sky output. Hamamatsu's 4.09 kWh/m²/day already reflects average cloudiness, so no further derating is needed for sizing.
- What panel tilt works best in Hamamatsu?
- At Hamamatsu's latitude (35°), a fixed tilt near 35° balances year-round yield. Winter-heavy loads favor latitude + 15°; summer-heavy, latitude − 15°.