May 2026
Solar energy projects can benefit from direct normal irradiance (DNI) and diffuse horizontal irradiance (DHI) measurements during all project phases, and several commercial measurement systems for DNI and DHI are available. Sun trackers with pyranometers and pyrheliometers can provide highly accurate measurements but are often impractical in solar energy applications. For less expensive and more robust sensors, it is often unclear which accuracy can be expected under a project site’s specific atmospheric conditions.
This article addresses this challenge through an experimental comparison of relevant sensor systems at up to six sites worldwide and evaluates the influence of relevant atmospheric parameters on the sensors’ accuracies.
Key Highlights
- Accuracy of practically feasible sensors for direct and diffuse irradiance evaluated.
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KO MS-90, Delta-T SPN1, RSI/RSP, PyranoCam, Sunto CaptPro, Kipp & Zonen CSD3 tested.
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ix sites worldwide included with approximately one year of measurements per site.
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nfluences of atmospheric and site conditions on the sensors’ accuracies investigated.
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Strong differences in accuracy found between the radiometer types.
