The sensing element consists of a wire-wound thermopile constructed of electroplated copper on constantan, covered with black paint that has a spectrally flat absorption response. It is protected from environment effects (wind, etc.) using two concentric glass dome covers.

Directional response: less than ±10 W·m^-2(for 1000 W·m^-2 beam radiation)

Temperature response: 1% (within an interval of 50°C)

Non-linearity: ±0.2% (from100 to 1000 W·m^-2)

Spectral range: : 300 to 2800 nm