Researchers in Spain developed a new model incorporating dynamic shading conditions in Madrid to evaluate yield and test control algorithms for vehicle-integrated PV (VIPV) systems.
Researchers from Spain’s Technical University of Madrid (UPM) have developed a model framework to simulate the performance of vehicle-integrated photovoltaic (VIPV) modules under realistic dynamic shading and seasonal conditions. The demonstrator model, based on urban conditions in Madrid, can calculate yields but can also be used to evaluate alternative maximum power point tracking (MPPT) algorithms.
The team combined simulation with high-resolution video recordings of predefined and characterized routes captured at different times of the year, to incorporate seasonal and daily variability. These were supplemented with meteorological data, vehicle positions and orientation, to estimate the radiation distribution affecting simulated PV modules.
“The novelty of the vehicle-integrated photovoltaic (VIPV) study is the focus on using the same routes throughout the seasons to understand the variation in radiation patterns and thus calculate the energy yield of VIPV modules in the same landscape,” said Ricardo Moruno Lobato, corresponding author of the study. pv magazine. “Given the high speed of light fluctuations, we used a high frames per second (fps) camera to record a video of the shadow profiles and then simulated a PV module under those same shadow profiles to evaluate its behavior.”
The recording had a frame rate of 240 fps. The simulated PV module was small in size to represent one sub-module of a larger system that could follow a distributed MPPT layout in which “each sub-module is linked to its own DC/DC converter with independent MPPT algorithms,” according to the research team.
According to the research, images were captured, transformed, segmented and converted into a temporary array of matrices of the shadows cast on each of the cells of the module. The framework integrated dynamic shading, irradiation and thermal modeling, IV curve estimation and electrical simulation of two common interconnection schemes, series and total-cross-tied (TCT).
The researchers evaluated the yield over five different routes near the UPM campus. Three routes in winter: morning (WM), afternoon (W-Mid) and afternoon (WA), and two in summer: morning (SM) and afternoon (SA). According to the study, the routes followed similar ranges and distances to ensure comparability. In addition, four predefined zones are included: dense trees, scattered trees, open low-rise and open mid-rise to reflect the roadside foliage and the height of the buildings.
“As for the electrical model, we used a two-diode model, although similar results can be achieved with a single diode,” says Moruno Lobato. He also said the team is using a “simplified flat-plank thermal model” to cover general trends, but noted that in reality an improved model is needed to be validated with experimental data.
Once the full set of IV curves were available, an ideal or lossless DC-DC converter with an integrated MPPT algorithm was simulated. Three MPPT algorithms were evaluated: fixed-voltage control; Perturb & Observe (P&O) and Artificial Neural Network (ANN).
“The results indicated that, if properly tuned, the P&O algorithm can achieve efficiency levels comparable to those of conventional PV applications for a substantial portion of the total energy harvested during vehicle movements,” explains Moruno Lobato. “Scenarios where dynamic conditions significantly hinder performance, and where an ANN-based method could provide an advantage, in most cases represent only a small portion of the total potential energy along a route (11-38%), with the exception of the W-Mid route (57%).”
They also said that “significant zonal and seasonal variations” affect the module’s performance, and that the main factor “hindering the performance ratio is the shading factor, which relegates other factors to a secondary role.”
The researchers concluded that their framework supports the simulation of different cell interconnection schemes and MPPT algorithms under identical irradiation and temperature conditions. “In addition, it provides access to the spatiotemporal evolution of shadow shapes and their distribution across categorized urban environments, representing a significant advance for the analysis of realistic dynamic shadows in VIPV applications,” they said.
Additional results and details of the study can be found in “Comprehensive VIPV energy harvest and MPPT evaluation under realistic dynamic shading in urban environments,” in Solar energy materials and solar cells. A team from Solar Added Value, a spin-off company of UPM, also participated in the study.
Noting that the outcome of the study “could provide key data for future VIPV studies,” Moruno Lobato said the research group is working on evaluating VIPV for buses based on data from radiation sensors of several bus lines in Madrid.
This content is copyrighted and may not be reused. If you would like to collaborate with us and reuse some of our content, please contact: editors@pv-magazine.com.
Popular content
