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New Trends in Green Construction
CALIBRATION AND PERFORMANCE OF TWO PYRANOMETERS PLACED ON TWO-AXIS SOLAR TRACKERS OF A PHOTOVOLTAIC PLANT
Isabel M. Moreno-Garcia, Rafael López-Luque, Marta Varo- Martínez, Victor Pallares-López, Isabel Santiago
Keywords: Renewable energy, photovoltaic, irradiance, pyranometer 1. Introduction
A photovoltaic (PV) system connected to the grid is mainly characterized for providing electrical energy in adequate conditions to be injected into the conventional distribution network. In these systems, the energy produced during the hours of sunshine is channeled directly (on-line) to the electrical grid. For a PV installation of this type to be dispatchable, one requirement is to have the entirely characterized, having always a precise knowledge of the state of operation of all the components that integrate it, such as photovoltaic modules or inverters (Santiago, 2017). In general, the operation of the different components of a PV installation is carried out by monitoring its operating parameters. Specifically, to analyze the behavior of photovoltaic generators, it is essential to monitor the irradiance (Woyte, 2014). The total irradiance in the plane of the PV field is defined as the radiant power, both direct and diffuse, affecting the unit of area of an inclined surface. The calibration of two pyranometers for succeeding installation in a PV plant with two-axis solar trackers is presented, as well as the performance of both when they were operational into the facility.
2. Materials and methods
The main advantages of having two irradiance measurements are the possibility of analyzing the effect of clouds in the production, and to ensure that the irradiance is always measured. For this end, two pyranometers were firstly calibrated and tested. For the calibration process, the two pyranometers were installed on the roof of the Department of Applied Physics of the University of Cordoba. A radiometric station that measures instantaneous irradiance from several pyranometers is avalible, storing data every 5 minutes. The pyranometers were mounted on a high pole to avoid shading. With the first measures the good operation of both devices could verified: the two measured the same and their values were practically equal to the rest of the installed sensors.
Pyranometer reference Pyranometer 1 Pyranometer 2
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Once calibrated, the pyranometers were placed with the same inclination and orientation as the PV panels of the installation, Figure 2(a). In this section, a snapshot of the monitoring system used for providing the state of the plant’s operation in real time is shown too, Figure 2(b). This
Calibration of the two pyranometers
Pyranometer of reference
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