Defining PV plant performance (and how to check it with satellite)!

Satellite data in PV plant check

The performance of your power plant is the key indicator to understand the current plant situation.

Perform timely actions to reduce costs and improve results as seen fit are possible.

The question is: how is it calculated?

The performance of your plant can be calculated as a comparison of the current plant behaviour with some reference production or energy yield assessment. The reference must include both a measurement of the energy generated and of the incoming irradiation.

Several Key Performance Indicators (KPI) are used to quantify the performance of the plants: Performance Ratio (PR) 1 and Technical Availability (A) 1 are very commonly used; both KPIs use the incoming irradiation as input for calculations.

Irradiation values can be assessed by different sensors: typically, pyranometers data, solar reference cells data, and satellite-based observations are used for this task.

At i-EM

We perform performance KPI calculation for your plant using ground measurement data and satellite-based data. Satellite-based data are especially useful in case of missing data or in general when data measured onsite are not available or not reliable. The longer the period considered, the lower the error will be for satellite-based irradiation data.

Since the solar measurements greatly influence the final KPI value, it is crucial to quantify accuracy and understand the specific characteristics of the instrument used to measure them.

You’d find great to read:

[1]: Woyte, Achim, Mauricio Richter, David Moser, Nils Reich, Mike Green, Stefan Mau, and Hans Georg Beyer. 2014. “Analytical Monitoring of Grid-Connected Photovoltaic Systems – Good Practice for Monitoring and Performance analysis.” Report IEA-PVPS T13-03: 2014. IEA PVPS.

[2]: SolarPowerEurope report “OM-Best-Practices-Guidelines-V3.0”, December 2018.

The plot shows the PR values of PV plants monitored by i-EM, averaged over Italian administrative areas (regions); Val D’Aosta, Basilicata and Trentino Alto Adige have no records and left in white color.