Solarposition.org

Chongqing · China · 29.45° N · 107.10° E

Solar position in Longtan

Sun position, daylight and the best solar panel angle for Longtan — computed for 29.45° N, 107.10° E, 694 m above sea level.

Sunrise today06:59103° ESE
Sunset today18:11256° WSW
Best panel angle19°year-round, facing south
Off-grid angle46°best for the darkest month

The sun right now

Azimuth180.0°
Elevation48.5°
At solar noon, 12:35Open on the sun map

Sun in Longtan today

Sunday, 25 October 2026 · local time UTC+8

EventTimeDirection / height
Astronomical dawn05:39sun 18° below horizon
Nautical dawn06:0712° below
Civil dawn06:356° below
Sunrise06:59103° ESE
Golden hour ends07:31sun 6° up
Solar noon12:3548.5° high
Golden hour starts17:39sun 6° up
Sunset18:11256° WSW
Civil dusk18:356° below
Nautical dusk19:0312° below
Astronomical dusk19:3118° below
Day length11 h 12 min

Sun path diagram for Longtan

Where the sun stands in the sky: the centre is straight overhead, the outer ring is the horizon. Numbers mark local clock hours.

15°30°45°60°75°N30°60°E120°150°S210°240°W300°330°June solstice678910111213141516171819EquinoxDecember solstice891011121314151617Today
  • June solstice
  • Equinox
  • December solstice
  • Today

On the June solstice the sun reaches 84.0° at solar noon in Longtan; on the December solstice only 37.1°. Sunrise swings from 62° ENE in June to 117° ESE in December — a 54° 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.

MonthSunriseSolar noonSunsetDay lengthNoon elevation
January07:4513:0218:1910 h 34 min40.7°
February07:2513:0518:4511 h 19 min50.0°
March06:5412:5819:0312 h 09 min60.8°
April06:1912:5019:2113 h 02 min72.4°
May05:5612:4819:4013 h 44 min80.7°
June05:5212:5319:5414 h 02 min84.0°
July06:0512:5819:5013 h 46 min81.0°
August06:2212:5419:2613 h 03 min72.7°
September06:3912:4418:4912 h 11 min61.3°
October06:5612:3618:1511 h 19 min49.9°
November07:2012:3717:5410 h 34 min40.7°
December07:4112:4917:5710 h 15 min37.1°

A year of daylight in Longtan

Each column is one day of 2026. Bright: sun above the horizon; soft: civil twilight; line: solar noon. Steps are daylight saving time changes.

00:0003:0006:0009:0012:0015:0018:0021:0000:00JanFebMarAprMayJunJulAugSepOctNovDec

Best solar panel angle in Longtan

Fixed array facing south (azimuth 180°). Energy per kWp from NASA POWER monthly climate, including clouds, temperature and snow reflection.

19°collects the most energy over a year: 899 kWh per kWp.

46°gives the most in the darkest month — the one an off-grid system is sized for.

50%60%70%80%90%100%0°10°20°30°40°50°60°70°80°90°Best year-round 19°Best worst-month 46°70°Yearly energyWorst-month energy
  • Yearly energy
  • Worst-month energy
TiltkWh/kWp per yearShare of best yearDecember kWh/kWp/dayBest ÷ worst month
0°86496%1.113.5×
15°898100%1.293.0×
19° year-round best899100%1.322.8×
29° = latitude88899%1.392.6×
30°88699%1.402.6×
45°83092%1.442.3×
46° off-grid best82592%1.442.2×
60°73482%1.412.0×
70°65172%1.341.7×
90°45951%1.131.5×

A fixed array in Longtan produces the most over a year at 19°. The design month for an off-grid system is December: at 46° it makes 1.44 kWh per kWp a day, 9% more than at 19°, and costs 8% of the yearly total. Why steep panels win winter.

Off-grid solar in Longtan at 70°

Daily energy of 1 kWp by month. Bars: panels at 70°. Line: panels at 19° (year-round best).

012345January: 1.37 (70°)1.4JanFebruary: 1.60 (70°)1.6FebMarch: 1.98 (70°)2.0MarApril: 2.01 (70°)2.0AprMay: 1.74 (70°)1.7MayJune: 1.62 (70°)1.6JunJuly: 2.09 (70°)2.1JulAugust: 2.35 (70°)2.3AugSeptember: 2.08 (70°)2.1SepOctober: 1.62 (70°)1.6OctNovember: 1.59 (70°)1.6NovDecember: 1.34 (70°)1.3Dec19°
MonthSun hours, flatSun hours at 70°kWh/kWp/day at 70°at 19°Mean temp.
January1.481.591.371.414.4 °C
February1.961.861.601.807.2 °C
March2.802.331.982.4811.9 °C
April3.542.422.012.9517.0 °C
May3.682.131.742.9120.7 °C
June3.752.021.622.8723.6 °C
July4.892.602.093.7526.1 °C
August4.692.902.353.7425.7 °C
September3.292.542.082.7721.9 °C
October2.111.951.621.8816.8 °C
November1.711.871.591.6211.5 °C
December1.361.561.341.325.8 °C
Year2.95 avg2.15 avg651 kWh899 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 880 Wp of panels at 70°, versus 890 Wp at 19°. The steep array is 1% smaller for the same winter. Size your own system.

Row spacing in Longtan

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.

3.5 mrow pitch at 70°

2.9 mrow pitch at 19°

Row spacing calculator

How Longtan compares in China

Against the other 2,094 places in China with climate data, for a fixed array at its best angle.

2064thof 2,095 places in China for sunshine, shared: 2.95 peak sun hours a day on flat ground.

−29%solar energy a year compared with the average place in China: 899 against 1,262 kWh per kWp.

−9 mindaylight on the longest day, compared with Shanghai: 14 h 02 min against 14 h 11 min.

19°best year-round tilt here; across China it runs from 14° in Haikou to 52° in Xilinji.

Of the 2,095 places in China, Nyêmo gets the most sun (5.75 peak sun hours a day) and Baima and 11 other places the least (2.91); Longtan ranks joint 2064th. In its darkest month, December, 1 kWp of off-grid panels at 70° makes 1.34 kWh a day here, against 2.06 kWh on average in China. The shortest day lasts 10 h 15 min, +8 min compared with Shanghai.

The sunniest places in China

Solar forecast for Longtan, next 48 hours

Expected output of 1 kWp at 70°, computed from the ICON-EU weather model of the Deutscher Wetterdienst (DWD), Europe.

Loading the latest forecast…

Questions about the sun in Longtan

What is the best solar panel angle in Longtan?
For a fixed array facing south, the best year-round tilt in Longtan is 19°, worth about 899 kWh per kWp a year. An off-grid system that has to get through December does better at about 46°.
What time is sunrise and sunset in Longtan today?
On 25 October 2026 the sun rises at 06:59 and sets at 18:11 local time (UTC+8), giving 11 h 12 min of daylight. Solar noon is at 12:35.
How many peak sun hours does Longtan get?
On a flat surface 2.9 hours a day averaged over the year, from 1.4 in December to 4.9 in July. Panels tilted at 70° receive 1.6 sun hours a day in December.
How high does the sun get in Longtan?
At solar noon the sun stands 84.0° above the horizon on the June solstice and 37.1° on the December solstice.
Is Longtan a good place for solar panels?
With 2.9 peak sun hours a day on flat ground, Longtan ranks joint 2064th of 2,095 places in China for sunshine. A 1 kWp array at the best angle (19°) makes about 899 kWh a year here, 29% less than the average place in China.

Places near Longtan

All places in China

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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.