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Dormer with shade on solar modules; Image: Courtesy of Stefan Winter, PTB

Solar panels in locations such as urban areas need to have their shade sensitivity quantified

Photovoltaic (PV) energy generation has an important role in realising EU targets for reduced greenhouse gas emissions.

Shading of PV modules is known as a common reason for underperforming of PV installations, especially in roof top installations. With increasing total installation goals necessary for the energy transition, more less favourable roof installation sites are being used. There is an awareness about the impact of shading situations on the overall output power and an increased number of PV modules claimed to be shading resistant are found on the market. However, until the work of this project shading resistance was not well defined and international standards for measuring cell energy outputs were inaccurate for shaded or indoor locations.

EMPIR project Metrology for emerging PV applications (19ENG01, Metro-PV) has developed a robust and pragmatic classification for the shading sensitivity of PV modules. This rating scheme can be easily used with a standard solar simulator or an outdoor test stand, and commercially available shading materials. In addition, the project consortium proposed classification intervals suited to the technologies that are already available.

The results were sent to IEC’s Technical Committee 82 Working Group 2 solar photovoltaic energy systems, for incorporation into standards, therefore ensuring that the work of this project will contribute to international standardisation.

The harmonised measurement methods for new technologies together with reduced measurement uncertainties will contribute to a clear reduction of the investment risk. It will empower consumers by enhancing a metric for PV efficiency based on energy output under European climate conditions by adding uncertainty evaluations to it and considering shading effects.

Project coordinator Stefan Winter from PTB said

‘The developed and proposed classification scheme enables a good differentiation of the shading tolerance and thus will give the end user the opportunity to select solar modules with a good shading tolerance if required’.

This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States

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