Niigata · Japan · 37.66° N · 138.93° E
Solar position in Tsubame
Sun position, daylight and the best solar panel angle for Tsubame — computed for 37.66° N, 138.93° E, 8 m above sea level.
The sun right now
Sun in Tsubame today
Sunday, 25 October 2026 · local time UTC+9
| Event | Time | Direction / height |
|---|---|---|
| Astronomical dawn | 04:33 | sun 18° below horizon |
| Nautical dawn | 05:04 | 12° below |
| Civil dawn | 05:35 | 6° below |
| Sunrise | 06:01 | 105° ESE |
| Golden hour ends | 06:38 | sun 6° up |
| Solar noon | 11:28 | 40.3° high |
| Golden hour starts | 16:18 | sun 6° up |
| Sunset | 16:54 | 255° WSW |
| Civil dusk | 17:21 | 6° below |
| Nautical dusk | 17:51 | 12° below |
| Astronomical dusk | 18:22 | 18° below |
| Day length | 10 h 53 min | |
Sun path diagram for Tsubame
Where the sun stands in the sky: the centre is straight overhead, the outer ring is the horizon. Numbers mark local clock hours.
- June solstice
- Equinox
- December solstice
- Today
On the June solstice the sun reaches 75.8° at solar noon in Tsubame; on the December solstice only 28.9°. Sunrise swings from 59° ENE in June to 119° ESE in December — a 60° arc along the horizon.
Sunrise, sunset and sun height by month
Values for the 21st of each month, local clock time including daylight saving time.
| Month | Sunrise | Solar noon | Sunset | Day length | Noon elevation |
|---|---|---|---|---|---|
| January | 06:55 | 11:55 | 16:55 | 9 h 59 min | 32.4° |
| February | 06:27 | 11:58 | 17:29 | 11 h 02 min | 41.8° |
| March | 05:47 | 11:51 | 17:56 | 12 h 09 min | 52.5° |
| April | 05:01 | 11:43 | 18:24 | 13 h 23 min | 64.2° |
| May | 04:30 | 11:40 | 18:51 | 14 h 21 min | 72.5° |
| June | 04:22 | 11:46 | 19:09 | 14 h 46 min | 75.8° |
| July | 04:38 | 11:50 | 19:02 | 14 h 23 min | 72.8° |
| August | 05:04 | 11:47 | 18:29 | 13 h 25 min | 64.5° |
| September | 05:30 | 11:37 | 17:43 | 12 h 13 min | 53.1° |
| October | 05:57 | 11:28 | 16:59 | 11 h 02 min | 41.7° |
| November | 06:30 | 11:29 | 16:29 | 10 h 00 min | 32.5° |
| December | 06:55 | 11:42 | 16:28 | 9 h 33 min | 28.9° |
A year of daylight in Tsubame
Each column is one day of 2026. Bright: sun above the horizon; soft: civil twilight; line: solar noon. Steps are daylight saving time changes.
Best solar panel angle in Tsubame
Fixed array facing south (azimuth 180°). Energy per kWp from NASA POWER monthly climate, including clouds, temperature and snow reflection.
29°collects the most energy over a year: 1149 kWh per kWp.
57°gives the most in the darkest month — the one an off-grid system is sized for.
- Yearly energy
- Worst-month energy
| Tilt | kWh/kWp per year | Share of best year | December kWh/kWp/day | Best ÷ worst month |
|---|---|---|---|---|
| 0° | 1038 | 90% | 1.11 | 3.9× |
| 15° | 1124 | 98% | 1.42 | 3.1× |
| 29° year-round best | 1149 | 100% | 1.63 | 2.6× |
| 30° | 1149 | 100% | 1.65 | 2.6× |
| 38° = latitude | 1137 | 99% | 1.73 | 2.3× |
| 45° | 1113 | 97% | 1.78 | 2.2× |
| 57° off-grid best | 1041 | 91% | 1.82 | 1.9× |
| 60° | 1017 | 89% | 1.81 | 1.9× |
| 70° | 924 | 80% | 1.78 | 1.7× |
| 90° | 685 | 60% | 1.57 | 1.6× |
A fixed array in Tsubame produces the most over a year at 29°. The design month for an off-grid system is December: at 57° it makes 1.82 kWh per kWp a day, 11% more than at 29°, and costs 9% of the yearly total. Why steep panels win winter.
Off-grid solar in Tsubame at 70°
Daily energy of 1 kWp by month. Bars: panels at 70°. Line: panels at 29° (year-round best).
| Month | Sun hours, flat | Sun hours at 70° | kWh/kWp/day at 70° | at 29° | Mean temp. |
|---|---|---|---|---|---|
| January | 1.54 | 2.06 | 1.83 | 1.75 | 1.6 °C |
| February | 2.30 | 2.66 | 2.37 | 2.47 | 1.7 °C |
| March | 3.45 | 3.35 | 2.96 | 3.43 | 4.4 °C |
| April | 4.49 | 3.48 | 3.01 | 4.01 | 9.3 °C |
| May | 5.21 | 3.31 | 2.80 | 4.25 | 14.9 °C |
| June | 5.12 | 3.01 | 2.49 | 3.96 | 19.3 °C |
| July | 4.62 | 2.84 | 2.31 | 3.56 | 23.3 °C |
| August | 4.86 | 3.43 | 2.80 | 3.96 | 24.9 °C |
| September | 3.89 | 3.48 | 2.88 | 3.52 | 21.3 °C |
| October | 2.90 | 3.32 | 2.82 | 2.99 | 15.5 °C |
| November | 1.92 | 2.71 | 2.34 | 2.22 | 9.9 °C |
| December | 1.38 | 2.03 | 1.78 | 1.63 | 4.5 °C |
| Year | 3.48 avg | 2.97 avg | 924 kWh | 1149 kWh |
Sizing example. To run a 1 kWh-per-day load through December on LiFePO4 batteries (charge controller, battery and inverter losses included) you need about 660 Wp of panels at 70°, versus 720 Wp at 29°. The steep array is 8% smaller for the same winter. Size your own system.
Row spacing in Tsubame
Distance between rows of 2 m long panels (slope length) so that no row shades the next between 10:00 and 14:00 solar time on the winter solstice.
4.6 mrow pitch at 70°
3.8 mrow pitch at 29°
How Tsubame compares in Japan
Against the other 1,215 places in Japan with climate data, for a fixed array at its best angle.
1088thof 1,216 places in Japan for sunshine, shared: 3.48 peak sun hours a day on flat ground.
−11%solar energy a year compared with the average place in Japan: 1,149 against 1,284 kWh per kWp.
+12 mindaylight on the longest day, compared with Tokyo: 14 h 46 min against 14 h 35 min.
29°best year-round tilt here; across Japan it runs from 17° in Miyakojima to 41° in Kushiro.
Of the 1,216 places in Japan, Miyakojima gets the most sun (4.34 peak sun hours a day) and Wakkanai and one other place the least (3.17); Tsubame ranks joint 1088th. In its darkest month, December, 1 kWp of off-grid panels at 70° makes 1.78 kWh a day here, against 2.14 kWh on average in Japan. The shortest day lasts 9 h 33 min, −11 min compared with Tokyo.
Solar forecast for Tsubame, next 48 hours
Expected output of 1 kWp at 70°, computed from the ICON-EU weather model of the Deutscher Wetterdienst (DWD), Europe.
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Questions about the sun in Tsubame
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Places near Tsubame
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A free, live card for Tsubame: where the sun is right now on today's path, a countdown to sunset or sunrise, the daylight change, the moon phase at night and the best panel angle.
Sun positions: NREL Solar Position Algorithm. Climate: NASA POWER monthly climatology (NASA Langley Research Center). Forecast: Deutscher Wetterdienst, ICON-EU (CC BY 4.0), processed. Places: GeoNames (CC BY 4.0). Time zones: IANA. Sources and licences.