Zoltan Varga

Mr. Zoltan Varga

Óbuda University, Budapest, Hungary
orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 October 2022 in Energies
Verified
Journal Article
Open access
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ZVZoltan Varga
Zoltan Varga
ERErvin Rácz
Ervin Rácz
In cases where a dye-sensitized solar cell (DSSC) is exposed to light, thermal energy accumulates inside the device, reducing the maximum power output. Utilizing this energy via the Seebeck effect can convert thermal energy into electrical current. Similar systems have been designed and built by other researchers, but associated tests were undertaken in laboratory environments using simulated sunlight and not outdoor conditions with methods that belong to conventional data analysis and simulation methods. In this study four machine learning techniques were analyzed: decision tree regression (DTR), random forest regression (RFR), K-nearest neighbors regression (K-NNR), and artificial neural network (ANN). DTR algorithm has the least errors and the most R2, indicating it as the most accurate method. The DSSC-TEG hybrid system was extrapolated based on the results of the DTR and taking the worst-case scenario (node-6). The main question is how many thermoelectric generators (TEGs) are needed for an inverter to operate a hydraulic pump to circulate water, and how much area is required for that number of TEGs. Considering the average value of the electric voltage of the TEG belonging to node-6, 60,741 pieces of TEGs would be needed, which means about 98 m2 to circulate water.

21 September 2025 in Energies
Verified
Journal Article
Open access
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ZVZoltan Varga
Zoltan Varga
MBMarek Bobcek
Marek Bobcek
ZČZsolt Čonka
Zsolt Čonka
ERErvin Rácz
Ervin Rácz
The dye-sensitized solar cell (DSSC) is a promising candidate, offering an attractive substitute for conventional silicon-based photovoltaic technologies. The performance advantages of the DSSC have led to a surge in research activity reflected in the number of publications over the years. To deliver data-driven analysis of DSSC performance, machine learning models have been applied. As a first step, a literature-based database has been developed and after the data preprocesses, Decision Tree (DT), Random Forest (RF), K-Nearest Neighbors (KNN), Support Vector Machine (SVM), xgboost (XGB), and Artificial Neural Network (ANN) algorithms were applied with stratified train-test splits. The performance of the models has been assessed via metrics, and the model interpretability relied on SHAP analysis. Based on the employed metrics and the confusion matrix, DT, RF, and KNN are the most accurate models for predicting DSSC efficiency on the developed dataset. Furthermore, it was revealed that synthesis temperature and the thickness of thin film were identified as the dominant drivers, followed by precursor and dye. Mid-tier contributors were morphological structure, electrolyte concentrations, and the absorption maximum. The results suggest that in optimizing the manufacturing process, targeted tuning of the synthesis temperature, the thickness of thin film, the precursor, and the dye are likely to improve the performance of the device. Therefore, experimental effort should concentrate on these factors.

1 August 2016 in International Journal of Hydrogen Energy
Verified
Journal Article
Closed access
RJRafael K. Járdán
Rafael K. Járdán
PSPeter Stumpf
Peter Stumpf
ZVZoltan Varga
Zoltan Varga
CEChristian Endisch
Christian Endisch
PSPéter Sipos
Péter Sipos
MSMiklós Simon
Miklós Simon

31 December 2022 in SYSTEM THEORY, CONTROL AND COMPUTING JOURNAL
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Journal Article
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ZVZoltan Varga
Zoltan Varga
ERErvin Rácz
Ervin Rácz
Amongst the several alternative resources, renewable energy source (RES) can provide continuous and clean energy. Furthermore, RESs have received a worldwide attention and an outstanding role is attributed to them. The sun energy can be exploited using light energy conversion applications such as photovoltaics. Dye Sensitized Solar Cell (DSSC) is third-generation photovoltaic device and a forwardlooking, easily producible solar cell. Nevertheless, buying a commercially available DSSC, datasheet and material information are unavailable. Thus, the purchased DSSC is a black box. The main motivation is that to develop a MatLab application which is able to determine the material information and parameters of the Dye Sensitized Solar Cell from some incoming parameters. The goal of the study is to describe the peration of the developed MatLab application which calculated the photogeneration rate in function of the thickness of the cell, the open-circuit voltage, and to illustrate its operation via an example. The photogeneration rate is solved using the numerical finite element method as a numerical procedure. In our model the Beer-Lambert law is implemented. The model takes into consideration the measured parameters of the light such as photoncount-wavelength spectrum, transmissionwavelength spectrum and irradiation intensity-wavelength spectrum. Furthermore, the open-circuit voltage is an elementary electric parameter of a solar cell.

12 August 2026 in Solar
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Journal Article
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Vladimír SzomosiVladimír Szomosi
Vladimír Szomosi
SBStanislav Baňački
Stanislav Baňački
JŠJúlius Šimčák
Július Šimčák
MBMarek Bobcek
Marek Bobcek
ZČZsolt Čonka
Zsolt Čonka
ZVZoltan Varga
Zoltan Varga
Deep networks dominate photovoltaic (PV) thermographic fault detection but need large annotated datasets and resist interpretation. We present a lightweight, interpretable infrared workflow combining support-vector-machine (SVM) module/background segmentation from four handcrafted features with an adaptive grid analysis labelling regions as nominal-intensity, high-intensity anomaly or low-intensity anomaly relative to a module-internal reference; the anomaly classes are inspection candidates, not confirmed faults. Evaluation used 21 close-range images of one 20 W module—recorded with the camera’s visible-light edge fusion active, so they are fused infrared/visible frames—and all 596 of a public five-sector UAV dataset. Segmentation against manual masks reached a mean intersection-over-union of 0.64; a feature ablation shows intensity statistics dominate, and an end-to-end Otsu pipeline gives almost the same high-intensity share (4.54% versus 4.50%): the SVM contributes reproducibility—removing the manual segmentation threshold, though not the empirical +48/−60 offsets—not accuracy. High-intensity regions concentrated in the module’s lower half, co-locating with a bus-bar defect known from hardware inspection—suggestive, not validated. The single-module, image-level close-range evaluation is optimistic, and the UAV shares, from a separately trained SVM, illustrate cross-domain application only. Segmentation runs at about 15 images per second on CPU. The method is a relative-intensity thermal screening workflow, not a validated defect-diagnosis or plant-health assessment method, and applies only where acquisition is controlled and the offsets are recalibrated for the target camera and palette.

2 September 2026 in Solar
Verified
Journal Article
Open access
PDF file
MBMarek Bobcek
Marek Bobcek
JKJozef Király
Jozef Király
Vladimír SzomosiVladimír Szomosi
Vladimír Szomosi
ZČZsolt Čonka
Zsolt Čonka
ZVZoltan Varga
Zoltan Varga
VĐVeljko Đurković
Veljko Đurković
Battery energy storage systems (BESSs) are increasingly coupled with photovoltaic (PV) generation, yet their deployment is governed by economics rather than by technical feasibility. This review synthesises 122 indexed Q1/Q2 studies (2016–2026) on the financial payback and return on investment of PV-coupled storage, extending the analysis to vehicle-to-grid (V2G) integration. Records retrieved from Scopus, Web of Science, IEEE Xplore, and the MDPI portal were screened to peer-reviewed journals, assigned to ten thematic clusters, appraised against a ten-criterion reporting-transparency rubric, and combined by narrative synthesis. Reported payback periods range from a few years to beyond the asset’s service life, and the levelized cost of storage spans roughly 170–350 USD/MWh. In the reviewed corpus, the retail-to-export price spread, the stacking of self-consumption, arbitrage, grid-service revenues, and degradation-aware operation each move returns in a consistent direction, whereas which of them binds hardest is a property of the case rather than a ranking the evidence supports. V2G is almost always analysed in isolation from stationary storage; an illustrative harmonised comparison indicates that it substitutes for stationary capacity rather than adding to it. The review maps the combined PV+BESS+V2G revenue stack and identifies an integrated, degradation-corrected, policy-sensitive economic model as the principal research gap.