Comparative Analysis of Monocrystalline, Polycrystalline and PERC Solar Cells— Evaluating Efficiency and Power Output Under Variable Conditions

Introduction:
Solar panels provide clean, renewable energy without harming the environment. This experiment focused on comparing the efficiencies of three specific types of solar cells: Monocrystalline, Polycrystalline, and PERC (Passive Emitter and Rear Cell). Each type of solar cell was tested using four different resistor values, and measurements of cell voltage and load current were taken at 20-minute intervals throughout the day to assess how variable sunlight affected performance. Additionally, this study aimed to evaluate the cost efficiency of each solar panel type, with the goal of either supporting or challenging previous findings on these solar cells.
Components and Methods:
Three types of solar cells—Monocrystalline, Polycrystalline, and PERC—were sourced online. The experimental setup included wires, a battery, a solar charger, load resistors, a breaker, voltmeters, and ammeters. To determine solar cell efficiency, two distinct circuits were designed. The first circuit was used to measure the efficiencies of the different cells, while the second circuit was designed to minimize fluctuations in data. In both setups, cell voltage and load current were recorded, and for the first circuit, cell current and charger voltage were also measured, all at 20-minute intervals.
Experimental Setup:
Each solar cell was connected to a V charger to monitor outputs such as Icell (Amps), Vcell (Volts), and Iload (Amps). Power output was calculated by multiplying Icell and Vcell. Key variables such as solar panel area, weather conditions, and overall efficiency were considered in the analysis. Resistor wattages were chosen according to electrical circuit design standards, with resistors rated at twice the estimated power load (e.g., a 50W estimated power required a 100W resistor).
Results:
The experiment revealed the relative efficiencies of Monocrystalline, Polycrystalline, and PERC solar cells. The PERC solar cell consistently outperformed the others, with a higher power-to-voltage ratio (Power-Vcell) across all load current (Iload) levels. Polycrystalline solar cells came in second, while Monocrystalline cells exhibited the lowest efficiency. The cost-efficiency of each type was also calculated, showing that while Monocrystalline cells had a higher raw efficiency, Polycrystalline cells were more cost-efficient. The relationship between power output and voltage was inverse across all cell types, allowing us to conclude that PERC solar cells are the most efficient, followed by Polycrystalline and Monocrystalline cells.
Conclusions and Future Work:
The study’s results indicate that PERC solar cells are the most efficient overall, with Polycrystalline cells being the most cost-effective. Between Monocrystalline and Polycrystalline, Monocrystalline cells demonstrated higher efficiency, but Polycrystalline outperformed in terms of cost-efficiency. Future research could explore several avenues for improvement, such as integrating an inverter to convert DC to AC voltage, or physically altering the structure of the solar cells to enhance performance. Additionally, optimizing cell design rather than merely collecting data from standard cells could provide deeper insights.
Acknowledgements:
This research was supported by a generous donation from Beckman Laser Institute Inc. to LS. The high school students (*) participated in the UCSD IEM OPALS internship. Special thanks to Dr. Shu Chien of UCSD Bioengineering and Dr. Lizhu Chen from CorDx Inc. for their contributions.