Veröffentlichungen und Präsentationen

Irradiance is fundamental in the energy production of photovoltaic (PV) modules and models can be developed using just irradiance data. However, module temperature has also significant impact on the power output. In locations with high ambient temperatures PV module performance can be significantly reduced. The aim of this work is to explore ways, using COMSOL Multiphysics^®, in which natural ventilation can be enhanced and passive cooling can be achieved at increased wind speeds.

A 2-dimensional model of an elevated photovoltaic (PV) module to study the thermal efficiency, using a COMSOL Multiphysics^® simulation, is presented. A Stationary study with Laminar Flow Conjugate Heat Transfer Multiphysics selection is used. This selection is ideal for solving conservation of energy, mass, and momentum in fluids as well as conduction in solids. In order to solve these equations, this selection automatically includes the Heat Transfer in Solids, Fluid domain conditions, and the Laminar Flow interfaces. A stationary PARDISO solver is used together with Adaptive Mesh Refinement in order to reconcile edge effects.

The PV module is composed of several components including glass, Ethyl vinyl acetate, silicon cell, Tedlar^® film, and the metallic frame. All these components are modeled as rectangular objects to form the PV module. The silicon cell is the component of the PV module that transforms solar energy into electric energy and is the primary heat source in the model. The PV module is assumed to be surrounded by air at ambient temperature. The model takes into account various wind speeds, tilt angles, and design configurations to explore optimal results. Varying these parameters has a noticeable impact on the thermal efficiency of a photovoltaic module where the results are consistent with literature involving both numerical and experimental studies.

The model proposed in this work has been proven useful in the prediction of the thermal behavior of a PV module and the cell temperature under operating conditions.

The Ross coefficients estimated by the proposed COMSOL Multiphsics^® model for the prediction of temperature from irradiance are within the range found in experimental studies.

Tilt angle has an important impact on the module temperature. It has been shown that there is more than 10 K decrease in the cell temperature when the tilt angle of the module varies from 10^o to 70^o. The change is larger for small tilt angles than for large angles, with the temperature of the upper edge being, in all cases, higher than that of the lower edge as expected. Similar behavior has been observed in related research. 

As expected when the wind speed rises, the temperature decrease is stronger in the module without frame. However, due to convergence and computational time, wind it has only been possible to do simulations with wind speeds up to 2 ms^-1.

Further work will focus in simulations with higher wind speeds and in the examination and quantification of the effect that factors, such type of ground cover, morphology of the ground and distance from the ground have on the thermal behavior of the PV module.