Improved Electrical Model and Experimental Validation of the PVMD Toolbox

Abstract

In the field of photovoltaics, tandem cells have emerged as a promising technology with high power conversion efficiencies. The academic society grew interest toward this technology due to its high generation capabilities at low production costs. For the time being, most of the research efforts are limited to the lab performance of these cells. However, real life performance studies allow for better understanding of the design effects and yield potentials of this technology. The commercially available yield prediction tools do not involve energy yield prediction models for tandem modules. In addition, they fall short at modelling all the aspects influencing the PV energy yield. The PVMD Toolbox, developed by the Photovoltaic Materials and Devices group at Delft University of Technology, is proposed to serve this need. This thesis presents the work done to develop version 4 of the toolbox. A calibrated lumped element model (CLEM) was developed to simulate the electric performance at the cell level. The CLEM combines the accuracy of physical models with the speed of lumped-element models to generate hundreds of thousands of simulations within a single minute. Additional models were implemented in the toolbox to account for the effects of cell interconnections and metallization on the energy output. Besides, a cell mapping algorithm was developed to reduce the AEY simulation time. This algorithm proved beneficial by reducing the number of required electric simulations by 86% at the small cost of 0.226% bias. Afterwards, the accuracy of the thermal and electric models was validated against two datasets. The simulated results showed a great agreement to the measurements with total energy yield deviations from the measurement of 2.65% and 4.15%, compared to 7.43% in version 3. Therefore, version 4 of the toolbox offers more accurate simulations with a reduced computation speed by a factor of 45.
The CLEM and cell interconnection models were utilized to perform energy yield simulations on tandem modules. Case studies were performed on c-Si/tandem modules to investigate the implications of design choices. After optimizing the STC output of four design options, the toolbox was used to simulate the energy yield for each of them. Then, the optical and electric performance of the modules were studied. The tandem modules proved advantageous, with energy yield increase ranging between 12.91% and 27.13% compared to SHJ modules. In addition, specific yield computations confirmed the sensitivity of tandem modules to meteorological conditions. The final result of this thesis is a first-time combination of modelling spectral irradiance, thermal, and cell and module electric aspects for energy yield simulations of tandem modules.