Reflectance Measurement Guidelines

A group of experts in the field of optical mirror reflectance characterization has been working together as members of Task III to create a document of an official SolarPACES reflectance measurement guideline.

Title of guidelines


Scope of Project

The guideline for reflectance characterisation of solar reflectors was developed under the framework of a two year project “Development of guidelines for standards for concentrating solar power (CSP) components” within the SolarPACES Task III: “Solar Technology and Advances Applications”. The project was created because of the urgent demand to normalize the qualification procedures of solar mirrors and to provide reliable performance analysis tools whose results are comparable within the solar community. Therefore the scope of this project was to prepare recommendations of procedures for presentation to the standardization organisations (ISO, ASME, DIN, AENOR, etc) that can be formulated into international standards with respect to the following topics

  1. Guidelines for reflectance characterisation.
  2. Guidelines for mirror panel and modules characterisation.
  3. Guidelines for receiver performance measurements.

The milestones of this project are listed below:

  • Develop draft standard procedures and distribute them among the SolarPACES Task III working group for discussion and iteration.
  • Organize a round robin test campaign based on the procedures defined in the proposed standards and publish the results in a conference paper.
  • Disperse the standards within the solar community through the SolarPACES website.

As a result, the version 2.5 of the guideline was published, based on the work at the technical meeting in Morocco on September 2012. This guideline was accepted as official SolarPACES reflectance guideline and replaced the old version 1.

The next step consisted on launching a new SolarPACES project titled “Reflectance Measurement Working Group under SolarPACES Task III” (2014-2017) to fund two workshops, under the coordination of CIEMAT and with the participation of the SRRR evaluators (ENEA, CEA, CENER, CIEMAT, DLR, and Fraunhofer-ISE), in addition to the University of Zaragoza (Spain) and PROMES (France). The goals of the workshops were as follow:

  1. To modify the version 2.5 of the SolarPACES guideline to include a simplified procedure for highly specular mirrors.
  2. Progress in the protocol to measure spectral near-specular reflectance of all kind of reflectors with the new advanced instruments.

The first workshop, hosted by ISE Fraunhofer, took place in July 2015, while the second one, hosted by CIEMAT-PSA, was hold in May 2017. As a result of the first workshop, a simplified procedure for highly specular mirrors was agreed and published in SolarPACES Conference 2015. During the second workshop, other aspects was addressed, such as the nomenclature, wavelength range for the solar reflectance, UV-weighted reflectance, measurement of aged or soiled mirrors, sample treatment and uncertainty calculation. All the agreements achieved during these two workshops are included in this current version of the SolarPACES Guideline (version 3.0), which substitute the previous version (version 2.5).

Please send your comments and suggestions for improvement to Aránzazu Fernández-García (

Download PDF Version of the “Reflectance Measurement Guidelines Ver. 3.1