Analogue spectrally flat Class B pyrheliometer, with heating

DR15 pyrheliometer is an ISO 9060 spectrally flat Class B (old ISO classification “first class”) instrument. It replaces the models DR01, DR02 and DR03. DR15 is used in tracker-mounted operation, and offers analogue millivolt output. The instrument offer the highest accuracy and highest data availability, featuring window heating at low offsets. At the same heating power, the heating has been improved with a factor 4, at a 4 times lower offset! Also take a look at the spectrally flat Class A DR20 Pyrheliometer, with a better temperature response than DR15.

  • ISO 9060 spectrally flat Class B
  • Heating at low offsets for high data availability
  • Low power consumption
  • Analogue millivolt output
  • Supplied with test report for the individual instrument


DR15 pyrheliometers are applied in high-accuracy measurements of the solar radiation received by a plane surface from a 5 ° full field of view angle. This quantity, expressed in W/m², is called “direct” solar radiation or DNI (direct normal irradiance). It is necessary to keep the instrument pointed at the sun by using a two-axis tracker.

The pyrheliometer features a precision ground and polished quartz window, a compact sized collimated tube and a thermopile sensor with black coated surface. DR15-A1 offers analogue output in millivolts. It can be connected directly to commonly used data logging systems. High data availability is attained by heating of the front window. This suppresses dew and frost deposition at a very low power consumption: DR15 needs only 1 W to keep its window free from dew and frost.

DR15 complies with the Class B specifications of the ISO 9060:2018 standard. Each DR15 pyrheliometer is supplied with test results for the individual instrument:

  • sensitivity
  • response time

Each DR20 pyrheliometer also includes a test report on temperature response, as required by ISO 9060 for Class A classification.

Suggested Use

  • Solar energy surveys
  • Solar resource assessments
  • Meteorological networks
  • Sites with dew and frost problems

Areas of Application

Meteorology / surface energy flux measurement
Solar energy / PV system performance monitoring



Direct solar radiation

ISO classification

Spectrally flat Class A

Calibration uncertainty

< 1.2 % (k = 2)




1 W at 12 VDC

Response time (95 %)

4 s

Full field of view angle

5 °

Slope angle

1 °

Zero offset

< ± 1 W/m²

Calibration traceability

to WRR

Spectral range

200 to 4000 x 10⁻⁹ m

Rated operating temperature range

-40 to +80 °C

Temperature response

< ± 0.4 % (-30 to +50 °C) with correction in data processing

Calibration certificate


Temperature response test of individual instrument

Report included

Standard cable length

5 m


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