Solar Panel Efficiency: Angle, Shading & Material

0 W

Panel output power

Sun & Panel Geometry

Sun elevation α 40°

Panel tilt β 30°

Shading Obstacle

Obstacle height 0 m

PV Material

Ambient temperature 25°C

Live Readouts

Angle of incidence θ

–

Shaded area

Effective irradiance

– W/m²

Cell temperature

– °C

How it works

Three independent loss mechanisms multiply together to set the panel's DC output power P:

cosθ = sin(α + β)                 (angle-of-incidence, Lambert's cosine law)
G_eff = G0 · max(0,cosθ) · (1 − s)  (effective irradiance, G0 = 1000 W/m²)
T_cell = T_amb + (G_eff/800)·(NOCT−20)   (NOCT thermal model, NOCT = 45°C)
η_T = η0 · [1 + γ·(T_cell − 25°C)]  (temperature-derated efficiency, γ<0)
P = G_eff · A · η_T                 (A = 1.7 m² panel area)

α (sun elevation) & β (panel tilt) — cosθ = sin(α+β) peaks at 1.0 exactly when β = 90°−α, which is why a fixed panel is tilted roughly to your latitude's average sun angle. Past 90° incidence the panel faces away from the sun and output drops to zero.
Shading obstacle — a pole of height h at a fixed 5 m stand-off casts a real geometric shadow of length h/tanα. Once that shadow reaches the panel's base, it climbs the panel's own surface exactly like a real cast shadow, and every fully-shaded cell (rendered dark below) stops contributing current — because PV cells are wired in series strings, a shaded fraction s cuts roughly that fraction of total power, not just its own share.
Material η0 & γ — monocrystalline silicon has the highest efficiency but a steeper negative temperature coefficient γ; thin-film CdTe is less efficient per m² but loses less power as it heats up.
NOCT model — real panels run hotter than the air around them under load; higher effective irradiance and warmer ambient air both raise cell temperature, which then feeds back to reduce η.

Illuminated cell Shaded cell

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Solar Panel Efficiency: Angle of Incidence, Shading & Material