As photovoltaic (PV) technologies evolve, understanding their environmental implications is crucial for a sustainable energy transition. IEA PVPS Task 12 analyzes the environmental impact of passivated emitter and rear cell (PERC) technology in PV installations in comparison to the monocrystalline silicon technology (AI-BSF) and the trend towards installing horizontal singla-axis tracker systems as opposed to fixed tilt systems. Primary data from one PERC and tracker manufacturer enable this study’s conclusions. Using the life cycle assessment (LCA) methodology, the study compares two locations in Italy with different irradiation patterns to evaluate the sensitivity to solar irradiation. The findings reveal that PERC technology and horizontal single-axis tracker systems demonstrate lower environmental impacts compared to Al-BSF and fixed tilt configurations.
IEA-PVPS
In 2022, the global solar photovoltaic (PV) generation experienced an unprecedented surge, marking a record increase of 270 TWh and reaching nearly 1 200 TWh worldwide. This remarkable growth underscores the pivotal role of solar energy in meeting the escalating global electricity demand while simultaneously mitigating greenhouse gas emissions. The driving force behind this was the establishment of new manufacturing capacities, alongside the transition from aluminum-back surface field (Al-BSF) cell technology to the more advanced passivated emitter and rear cell (PERC) technology around 10 years ago. The emergence of PERC as the standard technology is marked by its distinguishing features: an additional dielectric passivation stack on the rear of the cell and its possible bifaciality. This technology has replaced older cell structures like Al-BSF, primarily due to its improved efficiency gains in both PV cells and modules, leading to an increase in the nameplate power of modules. Moreover, there has been a notable rise in the adoption of Horizontal Single Axis Tracker systems, which offer higher kWh production per kW installed compared to fixed-tilt systems across various geographical locations. This shift towards more efficient and productive PV systems underscores a commitment to sustainable energy solutions.
Environmental Impact Assessment
While the energy production aspects of PV technologies have been extensively studied, a comprehensive understanding of their environmental footprint is essential. IEA PVPS Task 12 Experts have been employing their life cycle assessment (LCA) methodology to evaluate the environmental impacts associated with PERC technology in comparison to AI-BSF technology. By utilizing primary data from an Italian manufacturer, the report “Environmental Life Cycle Assessment of Passivated Emitter and Rear Contact (PERC) Photovoltaic Module Technology” provides an in-depth analysis of the complete life cycle of PV systems, encompassing manufacturing, installation, operation, and end-of-life phases. While based on analysis of data from only one manufacturer, the findings suggest that the transition from Al-BSF to PERC technology results in significant reductions in greenhouse gas emissions, energy consumption, and resource depletion throughout the life cycle of PV systems.
“The main thrust of our report is to analyze the impacts of the dominant technology in photovoltaics, using the LCA methodology and incorporating primary and up-to-date data,” Pierpaolo Girardi, co-Author of the report said. “This approach allows us to assert that electricity generated by PERC technology manufactured by an Italian company has a carbon footprint lower by 15% compared to electricity production with the currently most installed photovoltaic technology (Al BSF), and a 96% reduction compared to electricity produced by a typical Italian natural gas combined cycle power plant.”
Life Cycle Assessment Methodology
LCA is a structured, comprehensive method of quantifying material- and energy-flows and their associated emissions caused in the life cycle of goods and services. The ISO 14040 and 14044 standards provide the framework for LCA. IEA PVPS Task 12 subsequently developed guidelines, now in their 4th edition, to provide guidance on assuring consistency, balance, and quality to enhance the credibility and reliability of the results from LCAs on photovoltaic (PV) electricity generation systems.
Unveiling the Environmental Footprint
In their report, the Task 12 experts analyze two possible designs: (1) modules mounted on a horizontal single-axis tracker and (2) modules installed on a fixed structure. In addition, two possible PV locations with different irradiance levels are considered: one in the north of Italy and the other in the south of Italy; results shown here represent those for Southern Italy. The results, based on primary data from one manufacturer, are impressive:
- Greenhouse Gas Emissions: Transitioning from Al-BSF to PERC technology can lead to a reduction in greenhouse gas emissions per kWh produced across both locations. The additional passivation layer in PERC cells enhances energy conversion efficiency, thereby reducing the carbon intensity of electricity generation. Furthermore, the adoption of single-axis solar tracker systems amplifies this environmental benefit, as the increased energy yield per kW installed translates into lower emissions per unit of electricity produced.
The new IEA PVPS Task 12 report analyzes in detail the greenhouse gas emissions associated with using the PERC technology (see Fig. 1 for an example)