Solar Measurement Knowledge

In order to assure well-founded decisions in designing profitable solar power plants, the sun irradiation should be measured at the planned site.

It is also recommended measuring the produced electrical energy to keep the energy yield high.

Photovoltaic or CSP?

Each application requires specific measurements to get relevant irradiation information. The sun radiation on the earth surface combines

  • Direct Normal Irradiation (DNI) and
  • Diffuse Horizontal Irradiation (DHI).

Both are linked in the formula for Global Horizontal Irradiation (GHI):

GHI = DHI + DNI · cos (θ)
(where θ is the solar zenith angle)

Normally, on a sunny day the insolation is 100% GHI with 20% DHI and 80% DNI · cos (θ).

Solar Database PVGIS

The European Union introduced the PVGIS (Photovoltaic Geographical Information System) as part of the SOLAREC action to implement renewable energy in the EU as a long-term energy supply. The system provides a map-based inventory of solar energy resource and assessment of the electricity generation from PV power plants. more

Global Solar Atlas

The Global Solar Atlas is an online platform that provides solar measurement data for a number of countries for energy yield analysis. more

ISO 9060 Solar energy

– Specification and classification of instruments for measuring hemispherical solar and direct solar radiation more

IEC 61724-1:2021 Photovoltaic system performance

– Guideline for measurement, data exchange and analysis more

NREL "Best Practice Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications"

The NREL handbook is a comprehensive report, which summarizes important information for all steps of a solar energy project - reaching from required measurements and the design of meas-urement stations to forecasting the potential solar radiation. Additionally, NREL informs about measurement instruments and its application as well as sources for solar measurement data. Download here