In last decades, a rapid increase in installation of solar plants occurred worldwide. For an operating plant, the main exogenous limitation to optimal performance is represented by the environmental condition and dust presence on the PV module surfaces. Both solar radiation, the basic feedstock of the system, temperatures, influencing performances of its main components, and less-heralded factors such as wind speed, wind direction and rainfall, concur to generate the environmental conditions determining the potential expected plant yield against which actual plant performances are measured. For this reason, monitoring of the environmental characteristics of the site and, on the other hand, of the PV module itself, can give parameters to calculate the efficiency of the power plant.
The key variables to be monitored are:
- global irradiance,
- air temperature
- module temperature.
Also wind speed, wind direction and front storm distance are key factors in the field of risk prevention during extreme events.
LSI Lastem provides two different systems for PV monitoring application: a meteorological station that includes also a Performance Ratio Calculation and and a field system for Performance Ratio Calculation only.
In the meteorological station designed for environmental monitoring in PV plants, sensors for Performance Ratio calculation (pyranometer, air temperature, PV module surface temperature) are accompanied by a diffuse irradiance sensor, wind speed and wind direction sensor, storm front distance sensor and a rain gauge. Global Irradiance is the most important climatic parameter for the evaluation of the photovoltaic plant performance and, in this regard, LSI Lastem provides pyranometers with different classifications: Spectrally Flat Class A, B and C according to ISO9060: 2018 standard. State of the art ventilated and heated Spectrally Flat class A pyranometers are also available. System for soiling monitor can be integrated.
This station is normally connected by Modbus RTU or Modbus TCP to the plant SCADA system, but at the same time it can store the measurements and send them to one or several remote servers, produce alarms by SMS, E-mail and trigger, using electrical output, local devices in case of particular events.
The Field system is based on a Modbus Sensor Box module, the simplest and fastest way to connect environmental sensors to PLC/SCADA systems by Modbus RTU. The module can be easily interfaced to global irradiance sensors, each with its own sensitivity value, temperature sensors (air and PV module surface), anemometers and a storm front distance sensor.