A preparatory activity concerning the design phase of both the modules and the experimental apparatus for the VIPV application has been carried out. To identify the most suitable technology for the VIPV application, RSE foresees to compare the performance of PV modules made up of multi-junction (MJ) cells based on III-V compounds and made up of silicon. Concerning the formers, RSE started developing the design of the MJ cell structure, InGaP/InGaAs/Ge. In this modeling phase, CESI collaborated with RSE developing the metal grid design of the device.

The simulation results show that the triple junction cell should have a conversion efficiency value above 30%. From the modeling of the device, it was possible to make a prediction of the performance of the MJ module, in relation to the electrical connection scheme adopted for the cells. Concerning the silicon modules, two flexible prototypes have been developed, with an electrical layout optimized for VIPV technology. The modules were installed on a “photovoltaic roof rack” and subjected to initial tests in operating conditions, characterized by partial shading with the vehicle stationary condition.

A portable I-V tracer was preliminarily designed and built to acquire the current-voltage (I-V) curves of the PV modules integrated on the vehicle. The I-V tracer device includes a test circuit to vary the load, an I-V curve measurement and acquisition system, and a control system to automate the measurement and data storage process. The system can cyclically and continuously measure the I-V curves of PV modules with scanning and saving times in the order of milliseconds.

An experimental validation of the measurement system with a capacitive test circuit has been carried out, highlighting the importance updating the system with a DC-DC converter with Ćuk type resistive load, which will, therefore, be implemented in the next year. Eventually, a specific software has been developed that allows simulating the behavior of different MPPT algorithms in highly perturbed dynamic conditions. The software is also able to replicate the electrical behavior of the PV modules under test, generating I-V curves with variations at 500 ms intervals.

The research activity carried out will allow starting the experimental testing activities of PV modules on a moving vehicle in various scenarios, both urban and extra-urban, with the aim of identifying the PV technology and the MPPT algorithm best performing for the VIPV application.

The Report is available on the Italian site