Pyranometer selection guide: how to choose the best sensor for your application
Next-level instruments in every class
From the market leading pyranometer supplier: general guidelines for selection of the right pyranometer for your application. Main examples: use in PV system performance monitoring according to IEC 61724-1, use in meteorological networks and for diffuse radiation measurement. Customers prefer Hukseflux pyranometers for their unsurpassed measurement accuracy and their lowest total cost of ownership.
The right instrument for the application
Choosing the right instrument for your application might seem complex. We are here to help. First, consider these questions:
- are there standards for my application?
- what level of accuracy do I need?
- what maintenance will be available?
- what are the possibilities for mounting?
- how much electrical power is available?
Your answers to the above questions will help us to provide our recommendation for the best-suited pyranometer, including:
- pyranometer class
- maintenance and calibration policy
- estimate of the measurement accuracy
- electrical interfacing, use of electrical power
- mechanical mounting
Hukseflux pyranometer benefits
Hukseflux is a leading manufacturer, both in technology and market share, of pyranometers.
You can rely on the best measurement accuracy in every class. In more detail, thanks to superior instrument design you can trust on:
- unparalleled accuracy in every class
- exceptional reliability, ensuring consistent performance over time
- lowest cost of ownership, minimising maintenance costs and extending the product life span
We offer the right pyranometer for every application and budget.
Highest accuracy in every class
Pyranometers are classified according to ISO 9060 in 3 accuracy classes:
- spectrally flat Class A
- spectrally flat Class B
spectrally flat Class C
From Class C to Class B and from Class B to Class A, the achievable accuracy improves by a factor 2.
A general rule: the higher the required accuracy:
- the higher the cost of the instrument
- the higher the required level of maintenance (cleaning)
- the higher the required accuracy of calibration
| Measurand | hemispherical solar radiation |
| ISO 9060 clasification | spectrally flat Class A, B and C |
| Options | analogue and / or digital output; with Recirculating Ventilation and Heating (RVHTM), sapphire outer dome, or use with VU01 ventilation unit; cable length; heaters and internal temperature sensors; various mounting and levelling fixtures |
Highest reliability:
immunity to high voltages and currents - surges
SR300-D1, SR200-D1 and SR100-D1 are tested and classified for Industrial Environments according to IEC 61326-1 and IEC 61000-6-2. When designing a measuring system, pyranometer users may reach several levels of immunity. With the Surge Protection Device SPD01 this immunity can be increased to 4 kV. Up to 3 digital pyranometers can be protected with a single SPD01. A third-party SPD with similar specifications may be used instead.
To attain the required level of immunity for a given installation, some general system components should be included, such as:
- lightning protection system
- earthing and grounding network
- external surge protection in addition to the native on-board sensor protection
Lowest total cost of ownership
Customers prefer Hukseflux pyranometers for their unsurpassed measurement accuracy and lowest cost of ownership. Total ownership costs are primarily determined by installation, on-site inspection, accidental damage, and sensor calibration.
- coordinating internal and external protection and isolation reduces the requirements and costs for added protection devices
- preventive measures such as surge protection and dome protection help reduce the risk of accidental damage
- pyranometers must be calibrated every 2 years. Our worldwide calibration organisation helps reduce calibration costs by simplifying return logistics and turnaround times. Learn more about pyranometer calibration services.
- O & M saves time using built-in remote and on-site sensor diagnostics and spring-loaded levelling
Use in PV monitoring: IEC 61724-1
For high-accuracy PV system performance monitoring, the IEC 61724-1:2020 Photovoltaic System Performance Monitoring - Guidelines for Measurement, Data Exchange and Analysis - requires mitigation of dew and frost. SR300-D1 complies, for both Plane of Array (POA) and Global Horizontal Irradiance (GHI) without the need for additional accessories. For Reflected Horizontal Irradiance (RHI) lower class instruments may be used.
Use in meteorological networks
In WMO-No. 8, Guide to Meteorological Instruments and Methods of Observation, WMO recommends the use of spectrally flat Class B or “good quality” pyranometers such as the Hukseflux model SR100-D1 for network operation. Modern networks often use one level higher: spectrally flat Class A; such as our models SR300-D1 and SR200-D1.
Sensors made by Hukseflux passed validation and acceptance testing for a large number of National Meteorological Networks. Here are our references* from 2013 to 2024.
- India: National Institute of Wind Energy (NIWE) solar resource assessment network
- USA: National Ecological Observatory Network (NEON), observation network
- UK: Centre for Ecology & Hydrology (CEH), measurement / monitoring network
- India: India Meteorological Department (IMD), national measurement network
- Japan: Japan Meteorological Agency (JMA), national measurement network
- China: China Meteorological Administration (CMA), national measurement network, through a technology transfer project.
- Ecuador: National Meteorological and Hydrological Institute (INAMHI), national measurement network
- USA: The Atmospheric Radiation Measurement (ARM) multi-laboratory network of the U.S. Department of Energy (DOE)
- India: Defence Geo-Informatics Research Establishment (DGRE) climate observation network in the Indian Himalayas
*NOTE: the fact that a sensor is tested or used in a network does not constitute a formal endorsement by the test institute or network owner.
Use for diffuse radiation measurement
Diffuse solar radiation is usually measured using shaded pyranometers. The dominant measurement error is the zero offset a. SR300-D1, equipped with internal ventilation, has very low offsets. It outperforms the quartz dome instruments, traditionally used for this purpose, at a much lower cost level.
Instrument cleaning and calibration
The performance of high-class instruments strongly depends on cleaning. At a low maintenance level, the achievable accuracy will not be reliably attained. Consider using multiple instruments. The use of redundant instruments allows remote checks of one instrument using the other as a reference, which leads to a higher measurement reliability. For lower-class instruments, the relative loss of accuracy at a low maintenance level is less significant. At low maintenance intervals, the use of multiple low-class instruments is a good alternative to using a single high-class instrument.
Electrical interfacing
We can assist you in optimising the interfacing of the pyranometer to your data collection platform. Solutions vary from using a data logger as a local connection point for several different sensors to using transmitters incorporated in the pyranometer. The ideal solution for the solar PV industry and meteorological networks is the SR300-D1 pyranometer. Key features of this model: digital output and sensor communication using the industry-standard Modbus RTU protocol over 2-wire RS-485.
Table 1 The most common considerations when choosing a pyranometer for application in PV system performance monitoring, meteorological networks and diffuse solar radiation measurement.
 |  |  |  | |
| ||||
| ISO 9060 classification | Spectrally flat Class A | Spectrally flat Class A | Spectrally flat Class B | Spectrally flat Class C |
| IEC 61724-1 suitability for PV monitoring system Class | Class A for all locations and climatic conditions | Class A for locations where dew and frost are expected for less than 2 % of annual GHI hours | Class B for POA and GHI | Class B for POA and GHI |
| Diagnostics in datastream: alerts | Alerts for: instrument leakage change of tilt change of rotation heating and ventilation malfunction high internal humidity | Alerts for:
| Alerts for: high internal humidity | No alerts |
| Heating to mitigate dew and frost / improve data availability | heated | not heated | not heated | not heated |
| Surge immunity and EMC | IEC 61326-1 equipment classification: Industrial Equipment | IEC 61326-1 equipment classification: Industrial Equipment | IEC 61326-1 equipment classification: Industrial Equipment |
|
| PV system performance monitoring | +++++ | + | - | - |
| High accuracy meteorological networks | +++++ | ++++ | ++++ | - |
| Agro-meteorological networks | + | + | ++ | ++++ |
| Diffuse radiation reference (low offset) | +++ | ++ | - | - |
Read the full article here:
Hukseflux pyranometer selection guide (PDF)
