The SEM228T is a total solar radiation sensor, also called a pyranometer. It uses the thermoelectric effect. Sunlight heats a black sensing surface, and a thermopile turns the temperature difference into a voltage proportional to the radiation. It measures the 0.3–3 µm band of the solar spectrum. It connects to a SpaceEcho station and reports to EchoCloud.
SEM228T total solar radiation sensor installed outdoors (illustration).
Features
Thermopile sensing element
A wire-wound, electroplated thermopile under a highly absorptive black layer.
Temperature compensation
Corrects the reading for the sensor's own temperature.
Double-layer glass cover
95 % light transmittance. It reduces the effect of air convection and blocks radiation from the cover itself.
Several mounting uses
Facing up for global radiation, facing down for reflected radiation, tilted for radiation on a sloped surface, or with a shading ring for scattered radiation.
Aluminium housing
With a choice of RS-485 or analogue output.
Specifications
Measuring range
0–2000 W/m²
Spectral range
0.3–3 µm
Resolution
1 W/m²
Accuracy
±3 %
Annual stability
≤ ±3 %
Sensitivity
7–14 µV per W/m²
Response time (99 %)
≤ 30 s
Non-linearity error
≤ ±3 %
Cosine response error
≤ ±5 %
Directional error
≤ ±30 W/m²
Tilt error
≤ ±5 %
Temperature response error
≤ ±8 % (−40–40 °C)
Spectral selectivity
≤ ±10 %
Internal resistance
about 300 Ω
Output
RS-485 (Modbus-RTU), 4–20 mA, 0–5 V or 0–10 V, by order code
Supply voltage
10–30 V DC, or none for the passive output
Power consumption
0.8 W (RS-485); 1.2 W (4–20 mA, 0–5 V, 0–10 V)
Operating temperature
−40–60 °C
Housing
Aluminium
Cable length
Configurable
Related radiation sensors
The SEM228T and the UV Sensor measure different parts of the spectrum, so they do not replace each other.
