howmuchsun

Solar panel angle in Beau Bassin-Rose Hill

In Beau Bassin-Rose Hill, fixed panels collect the most energy over a year tilted 18° from horizontal and facing north. But anything between 10° and 30° is within 2% of the best, so the pitch you already have is probably fine.

What is your roof worth?

Of the maximum 98% facing north, 30° pitch
Best here 18° facing north
Good-enough range 10–30° within 2% of the maximum

Every roof, scored

Percentage of the maximum possible annual yield, for each combination of orientation and pitch in Beau Bassin-Rose Hill.

Percentage of maximum annual yield by roof orientation (rows) and pitch (columns).
Roof faces 15° 30° 45° 60° 90°
North 96% 100% 98% 91% 80% 47%
North-east / north-west 96% 98% 96% 89% 78% 52%
East / west 96% 94% 88% 80% 70% 50%
South-east / south-west 96% 89% 78% 65% 53% 34%
South 96% 87% 73% 56% 41% 22%

Why "tilt equals your latitude" is wrong here

The rule of thumb says tilt your panels at your latitude — 20° for Beau Bassin-Rose Hill. The real optimum is 18°, 2° lower than the rule suggests.

Two reasons, both geometric. Summer days are much longer than winter ones, so the year's energy is weighted toward a higher sun than the annual average. And a low winter sun sends its light through a long slant of atmosphere, arriving weak — tilting to catch it costs more in summer than it wins in winter.

In fairness to the rule: following it here would cost you only 0.0%. It is wrong, but it is not expensive.

Seasonal angles

If you can adjust your panels twice a year, these are the angles to use. Most people should not bother — the gain is small and the ladder is real.

SettingTiltFacing
Fixed, all year18°north
Summernorth
Winter45°north
Flat on the ground

A flat installation here keeps 96% of the maximum; mounted vertically on a wall, 47%.

Other cities in Mauritius

Assumptions

  • These are angles and percentages, never kilowatt-hours. Optimal angles are driven by geometry and are robust. Absolute energy output depends on measured irradiance, cloud, soiling and hardware, none of which are modelled here.
  • Clear sky, no shading. Trees, chimneys, neighbouring buildings and terrain are ignored, and they can dominate everything on this page.
  • Fixed panels. Trackers follow the sun and change the answer entirely.
  • Ordinary ground. Reflectance is taken as 0.2, typical for grass and soil. Snow reflects far more and favours steeper tilts.

Full methodology, sources and known limitations