Photovoltaic system performance

Two SR30 pyranometer positioned on a bracket, horizontally and in plane of array, next to a solar panel.
The SR30 pyranometer is an example of an PV monitoring sensor, which can be used in two orientations (horizontal and in plane of array) for measuring irradiance.

Photovoltaic system performance is a function of the climatic conditions, the equipment used and the system configuration. PV performance can be measured as the ratio of actual solar PV system output vs expected values, the measurement being essential for proper solar PV facility's operation and maintenance. The primary energy input is the global light irradiance in the plane of the solar arrays, and this in turn is a combination of the direct and the diffuse radiation.[1]

The performance is measured by PV monitoring systems, which include a data logging device and often also a weather measurement device (on-site device or an independent weather data source). Photovoltaic performance monitoring systems serve several purposes - they are used to track trends in a single photovoltaic (PV) system, to identify faults in or damage to solar panels and inverters, to compare the performance of a system to design specifications or to compare PV systems at different locations. This range of applications requires various sensors and monitoring systems, adapted to the intended purpose. Specifically, there is a need for both electronic monitoring sensors and independent weather sensing (irradiance, temperature and more) in order to normalize PV facility output expectations. Irradiance sensing is very important for the PV industry and can be classified into two main categories - on-site pyranometers and satellite remote sensing; when onsite pyranometers are not available, regional weather stations are also sometimes utilized, but at lower quality of data; the Industrial IoT-powered sensorless measurement approach has recently evolved as the third option.

Sensors and photovoltaic monitoring systems are standardized in IEC 61724-1[2] and classified into three levels of accuracy, denoted by the letters “A”, “B” or “C”, or by the labels “High accuracy”, “Medium accuracy” and “Basic accuracy”. A parameter called the 'performance ratio'[3] has been developed to evaluate the total value of PV system losses.

  1. ^ Myers, D R (Sep 2003). "Solar Radiation Modeling and Measurements for Renewable Energy Applications: Data and Model Quality" (PDF). Proceedings of International Expert Conference on Mathematical Modeling of Solar Radiation and Daylight. Retrieved 30 December 2012.
  2. ^ IEC 61724-1:2017 – Photovoltaic system performance – Part 1: Monitoring (1.0 ed.). International Electrotechnical Commission (IEC). 2017 [1998-01-01]. Archived from the original on 2017-08-25. Retrieved 2018-05-16.
  3. ^ Marion, B (); et al. "Performance Parameters for Grid-Connected PV Systems" (PDF). NREL. Retrieved 30 August 2012.