The Sunshine Sensor type BF3 is a new sensor, which uses an array of photodiodes and a shading pattern to measure the Direct and Diffuse components of solar radiation, and calculate whether the sun is shining.

The special pattern of clear and opaque areas on the acrylic dome is matched to the pattern of photodiodes in such a way that at least one photodiode always sees an unobstructed solar disc and at least one is always in full shadow. Worldwide patents are being applied for, to cover this unique technique (UK reference is 9719614.1).

The onboard microprocessor uses these readings to calculate the Direct, Diffuse and Total solar radiation values. The sensor provides 2 analogue outputs, corresponding to the Diffuse and Total components, and a digital output of sunshine presence.

BF3 sensor photodiodes are cosine corrected and calibrated for the measurement of PAR quanta (PAR = Photosynthetically Active Radiation, ~ 400 - 700 nm). It is planned that future versions of this sensor will incorporate photodiodes optimized for global solar radiation.

Sunshine Duration

The Sunshine Sensor type BF3 provides an output indicating whether the sun is shining. It measures Sunshine Hours indirectly using a simple equation based on both the Total PAR radiation, and the ratio of Total to Direct PAR.

The BF3 does not need to be adjusted or repositioned to track the sun - a distinct advantage over devices with shadow rings.