Technical Article

Calculation of Performance Ratio (PR) in photovoltaic systems

Article addresses the factors that influence this index and the importance of monitoring it regularly

Published September 26, 2024, 11:52 pm Updated 13 2025 October, 08: 48

Reading 1 min read

Measuring radiation on photovoltaic modules is the basis for calculating the PR of a photovoltaic plant. Photo: Canal Solar

Of the various indexes for analyzing energy generation in photovoltaic systems, PR (Performance Ratio) is one of the most used to evaluate the efficiency of photovoltaic plants.

The PR is a crucial indicator, as it helps the UFV O&M (Maintenance Operation) team to identify unexpected losses in the system, indicating, for example, excessive shadows due to vegetation, or excessive loss due to dirt in the photovoltaic modules.

Furthermore, by comparing the PR of photovoltaic plants with different types of technologies and manufacturers of photovoltaic modules, inverters and structures, one can have a good decision index for choosing the components and manufacturers of a new solar plant project to make up an investor's generation portfolio.

This article will cover the basic concepts, the formula for calculating PR, the factors that influence this index, and the importance of monitoring it regularly.

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The opinions and information expressed are the sole responsibility of the author and do not necessarily represent the official position of the author. Canal Solar.

About the Author

Thiago Farias

Engineer at CS Consultoria and professor of courses on storage and power plants at Canal Solar holds a degree in Electrical Engineering from FEI. He specializes in electrical projects, with an emphasis on detailed design of photovoltaic power plants. He has experience in protection studies for substations, medium and low voltage projects, grounding projects, generation performance analysis, simulation and modeling of photovoltaic plants, regulatory analysis for distributed generation, and financial feasibility studies.

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