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Pyranometer Delta-T Sunshine SPN1

• Measures global (total) and diffuse irradiance in W/m²
• WMO sunshine threshold: 120 W/m² direct beam
• No routine adjustment or polar alignment
• No moving parts, shade rings or motorised tracking
• Works at any latitude
• Unique ground glass dome
• Wideband thermopile sensors
• Near ideal spectral and cosine response
• Standard output sensitivity
• Matches or exceeds the ISO First Class standard and the
WMO Good Quality standard for a solar pyranometer in
all respects apart from the spectral response – which is
accurate to ±10% over 0.4 to 2.7 μm

Make : Delta T


The Sunshine Pyranometer is a patented, meteorological class instrument, with built-in heating, designed for longterm outdoor exposure. It is an affordable alternative to shade-ring pyranometers, pyrheliometers and traditional sunshine recorders. The SPN1 is exceptionally easy to use; it needs no routine adjustment or polar alignment and works at any latitude.

Unique Design
The Sunshine Pyranometer uses an array of seven, miniature thermopile sensors and a computer generate shading
pattern to measure the direct and diffuse components of incident solar radiation. The shading pattern and thermopiles are arranged so that at least one thermopile is always fully exposed to the solar beam, and at least one is fully shaded from it, regardless of the position of the sun in the sky. All seven thermopiles receive an equal amount of diffuse light. From the individual thermopile readings, a microprocessor calculates the global and diffuse horizontal irradiance and from these values an estimate of sunshine state is made. The Sunshine Pyranometer is protected by patents EP 1012633 & US 6417500.

SPN1 Design Principles
The principles used in the Sunshine Pyranometer have been tried and tested in the Delta-T BF3 Sunshine Sensor. The original design has been enhanced, using miniature thermopile sensors, a high quality ground glass dome and aluminium housing. The electronics have also been redesigned for higher accuracy and lower power consumption. Then SPN1 computes direct radiation by subtracting the diffuse from the global (total) radiation.

The Sunshine Pyranometer provides 2 analogue voltage outputs for global and diffuse radiation, and a digital output
for sunshine duration which can be connected to data loggers. Readings can be obtained directly from the RS232 port.

An internal heating keeps the dome clear of dew, ice and snow down to -20°C (in still air conditions), ensuring reliable readings in difficult climatic conditions.


Description / Value

Spectral range

0 to > 2000 W/m²


0.6 W/m² = 0.6mV

Analog output sensitivity

1mV = 1 W/m²

Analog output range

0 … 2500 mV

Sunshine status threshold

120 W/m²

Sunshine status output

No sun = open circuit Sun = short circuit to ground

Accuracy: sunshine status

± 10% sun hours with respect to the threshold

Accuracy: cosine correction

± 2% of incoming radiation over 0 … 90° zenith angle

Accuracy: azimuth angle

± 5% over 360° rotation

Quality Standard

SPN1 matches or exceeds ISO First Class standard and WMO Good Quality standard for solar pyranometers in all respects apart from spectral response – which is accurate to ±10% over 0.4 to 2.7 μm

Overall Accuracy

± 5% daily integrals

Global (Total)

± 5% ± 10 W/m2 hourly averages

Diffuse Radiation

± 8% ± 10 W/m² individual readings Accuracy figures give 95% confidence limits, i.e. 95% of individual readings will be within stated limits under normal climactic conditions.

Power requirements

2 mA (excluding heating power) 5 … 15 VDC

Heating power

12 … 15 VDC, up to 1.5 A

Heating control

Continuously variable up to 20 W output for external temperatures below 0°C

Lowest snow & ice-free temperatures (with heating in use)

Lowest snow & ice-free temperatures (with heating in use)

Temp coefficient

± 0.02% per °C typical (-20 … +70°C)

Temperature range

-40 … +70°C

Recalibration / stability

Factory calibration recommended every 2 years

Spectral response

400 … 2700 nm

Spectral sensitivity variation

10% typical

Latitude capability

-90 … +90°C


8-pole plug (M12)


8-wire cable, length: 5 m


IP67 sealing

Mounting options

3 x M5 tapped holes in base; 108 mm pcd, 120° spacing

Size / weight

140 mm (diameter) x 100 mm (height), 940g