Analysis of mesh screens for outdoor i-v curve measurements of pv modules at several irradiance levels

Mesh screens can be installed over a photovoltaic (PV) module to provide varying degrees of outdoor solar irradiance for I-V curve measurements. In such tests, it is often not possible to cover the PV module and the irradiance sensor with the mesh screen at the same time, requiring the transmissivity of the mesh to be accurately measured beforehand. This paper describes a measurement method and evaluates the uncertainty in determining the transmissivity of mesh screens used to attenuate solar radiation on PV modules. The method involves modeling the short-circuit current of the PV module as a function of irradiance and temperature indoors and measuring the transmissivity of mesh screens outdoors. Two mesh screens with nominal transmissivities of 50 % and 70% were assembled and used in single-layer and double-layer configurations, resulting in four different mesh filters. The transmissivity of each configuration was measured under four different conditions obtained by combining two angles of incidence for solar radiation - normal and 30 degrees - and using two PV modules, one with monocrystalline and the other with polycrystalline silicon cells. The proposed measurement method succeeded in measuring the transmissivity and determining the optimal sample size for all mesh screen configurations, taking 5 to 7 measurements to obtain an uncertainty of less than 1%. The work highlights the importance of measuring the transmissivity of mesh screens and provides valuable results for future research using this method to study the performance of PV modules at low irradiance levels.