Reunion · Reunion · 21.29° S · 55.41° E
Solar position in Saint-Louis
Sun position, daylight and the best solar panel angle for Saint-Louis — computed for 21.29° S, 55.41° E, 40 m above sea level.
The sun right now
Sun in Saint-Louis today
Sunday, 25 October 2026 · local time UTC+4
| Event | Time | Direction / height |
|---|---|---|
| Astronomical dawn | 04:22 | sun 18° below horizon |
| Nautical dawn | 04:49 | 12° below |
| Civil dawn | 05:16 | 6° below |
| Sunrise | 05:39 | 103° ESE |
| Golden hour ends | 06:09 | sun 6° up |
| Solar noon | 12:02 | 80.9° high |
| Golden hour starts | 17:55 | sun 6° up |
| Sunset | 18:25 | 257° WSW |
| Civil dusk | 18:48 | 6° below |
| Nautical dusk | 19:15 | 12° below |
| Astronomical dusk | 19:42 | 18° below |
| Day length | 12 h 46 min | |
Sun path diagram for Saint-Louis
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 45.3° at solar noon in Saint-Louis; on the December solstice only 87.8°. Sunrise swings from 65° ENE in June to 116° ESE in December — a 51° 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 | 05:53 | 12:29 | 19:05 | 13 h 13 min | 88.6° |
| February | 06:11 | 12:31 | 18:51 | 12 h 40 min | 79.2° |
| March | 06:22 | 12:25 | 18:28 | 12 h 06 min | 68.4° |
| April | 06:32 | 12:16 | 18:01 | 11 h 30 min | 56.8° |
| May | 06:43 | 12:14 | 17:45 | 11 h 02 min | 48.5° |
| June | 06:55 | 12:20 | 17:45 | 10 h 50 min | 45.3° |
| July | 06:54 | 12:24 | 17:55 | 11 h 01 min | 48.3° |
| August | 06:37 | 12:21 | 18:06 | 11 h 29 min | 56.7° |
| September | 06:09 | 12:11 | 18:14 | 12 h 05 min | 68.1° |
| October | 05:42 | 12:03 | 18:23 | 12 h 41 min | 79.5° |
| November | 05:27 | 12:04 | 18:40 | 13 h 13 min | 88.7° |
| December | 05:33 | 12:16 | 18:59 | 13 h 26 min | 87.8° |
A year of daylight in Saint-Louis
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 Saint-Louis
Fixed array facing north (azimuth 0°). Energy per kWp from NASA POWER monthly climate, including clouds, temperature and snow reflection.
20°collects the most energy over a year: 1719 kWh per kWp.
34°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 | June kWh/kWp/day | Best ÷ worst month |
|---|---|---|---|---|
| 0° | 1631 | 95% | 3.03 | 1.9× |
| 15° | 1714 | 100% | 3.72 | 1.4× |
| 20° year-round best | 1719 | 100% | 3.90 | 1.4× |
| 21° = latitude | 1719 | 100% | 3.94 | 1.3× |
| 30° | 1695 | 99% | 4.18 | 1.2× |
| 34° off-grid best | 1674 | 97% | 4.26 | 1.2× |
| 45° | 1578 | 92% | 4.38 | 1.3× |
| 60° | 1372 | 80% | 4.31 | 1.7× |
| 70° | 1194 | 69% | 4.12 | 2.2× |
| 90° | 807 | 47% | 3.40 | 3.4× |
A fixed array in Saint-Louis produces the most over a year at 20°. The design month for an off-grid system is June: at 34° it makes 4.26 kWh per kWp a day, 9% more than at 20°, and costs 3% of the yearly total. Why steep panels win winter.
Off-grid solar in Saint-Louis at 70°
Daily energy of 1 kWp by month. Bars: panels at 70°. Line: panels at 20° (year-round best).
| Month | Sun hours, flat | Sun hours at 70° | kWh/kWp/day at 70° | at 20° | Mean temp. |
|---|---|---|---|---|---|
| January | 6.58 | 2.54 | 2.04 | 4.83 | 26.4 °C |
| February | 6.39 | 3.23 | 2.61 | 4.94 | 26.7 °C |
| March | 5.74 | 3.96 | 3.22 | 4.76 | 26.4 °C |
| April | 4.98 | 4.66 | 3.81 | 4.50 | 25.6 °C |
| May | 4.20 | 4.90 | 4.04 | 4.10 | 24.2 °C |
| June | 3.83 | 4.97 | 4.12 | 3.90 | 22.7 °C |
| July | 4.05 | 5.04 | 4.19 | 4.08 | 21.8 °C |
| August | 4.83 | 5.04 | 4.20 | 4.59 | 21.5 °C |
| September | 5.83 | 4.62 | 3.84 | 5.12 | 21.9 °C |
| October | 6.58 | 3.69 | 3.04 | 5.31 | 22.8 °C |
| November | 7.02 | 2.74 | 2.22 | 5.24 | 24.0 °C |
| December | 7.19 | 2.36 | 1.89 | 5.16 | 25.5 °C |
| Year | 5.60 avg | 3.98 avg | 1194 kWh | 1719 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 620 Wp of panels at 70°, versus 300 Wp at 20°. Here the lower tilt is the better winter choice — the sun stays high enough. Size your own system.
Row spacing in Saint-Louis
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.
2.8 mrow pitch at 70°
2.6 mrow pitch at 20°
How Saint-Louis compares in Reunion
Against the other 13 places in Reunion with climate data, for a fixed array at its best angle.
11thof 14 places in Reunion for sunshine: 5.60 peak sun hours a day on flat ground.
−1%solar energy a year compared with the average place in Reunion: 1,719 against 1,733 kWh per kWp.
+2 mindaylight on the longest day, compared with Saint-Denis: 13 h 26 min against 13 h 24 min.
20°best year-round tilt here; across Reunion it runs from 19° in Saint-Denis to 20° in Saint-Paul.
Of the 14 places in Reunion, Le Port and one other place get the most sun (5.71 peak sun hours a day) and Saint-Pierre the least (5.56); Saint-Louis ranks 11th. In its darkest month, December, 1 kWp of off-grid panels at 70° makes 1.89 kWh a day here, against 1.88 kWh on average in Reunion. The shortest day lasts 10 h 50 min, −2 min compared with Saint-Denis.
Solar forecast for Saint-Louis, 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 Saint-Louis
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A free, live card for Saint-Louis: 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.