Presets
Playback
Sun, sky and mirrors
Each mirror normal is the bisector of the direction to the sun and the direction to its aim point, so the reflected ray lands on the receiver. Efficiency falls when the sun is low because the mirrors tilt away from the beam (cosine loss).
Operation
Model checks
The science
What is modelled
Thirty-six flat mirrors reflect direct sunlight to a receiver on a tower. Each mirror is steered every step to the bisector of the sun and target directions; the reflected beam makes a Gaussian spot whose captured fraction is integrated over the receiver grid, and the receiver heats against convection and radiation.
Equations
- Solar declination and hour angle give the sun vector; mirror normal
n = unit(s + t)for sun direction s and target direction t. - Input power
DNI (1 - haze) A (n . s); reflected power times reflectivity andexp(-0.0009 d). - Receiver:
C dT/dt = Q - h A (T - Ta) - eps sigma A (T^4 - Ta^4).
Checks run in the page
- Noon solar altitude against 90 - |latitude - declination|.
- Law of reflection for a tracked mirror.
- The sun to receiver energy chain.
- Receiver steady-state temperature against bisection on the heat balance.
Honest simplifications
No shading or blocking between mirrors, no spillage beyond the Gaussian tail, a lumped receiver heat capacity, no atmospheric refraction and an approximate solar-position formula. Not a plant design tool.
What to try
- Press Winter morning and see the cosine loss lower the optical efficiency.
- Press Stick / free mirror 14 and watch the spot drift off the receiver as the sun moves.
- Press Hazy and windy: the flux map spreads and the captured power drops.