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SPN1 Sunshine Pyranometer

Make:  Delta T        Model: SPN1
✅ Global (Total) and Diffuse irradiance in W.m-2
✅ WMO sunshine threshold: 120 W.m-2 direct beam.
✅ No routine adjustment or polar alignment
✅ No moving parts, shade rings or motorised tracking
✅ Works at any latitude

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.


Delta T






140mm dia x 100mm (h)


Two analogue voltage outputs( 0-2500mV) for global and diffuse radiation, and a digital output for sunshine duration

Measuring range

0 to >2000 W.m-2



Power supply

2mA (excluding heater power), 5V – 15V DC


Spectral sensitivity variation: 10% typical
Analogue output sensitivity: 1mV = 1 W.m-2

Spectral range


Tilt response

Negligible errors

Spectral response


Protection Level

IP67 sealing

Complete zero off-set c)

<3 W.m-2 for a change of 5°C/hr in ambient temperature
<3 W.m-2 dark readingLowest snow & ice-free temperatures (with heating in use)

Response time (95%)

< 200ms