Solar photovoltaic (PV) energy systems are a fundamental component of sustainability due to their demonstrated environmental [1] and economic [2] advantages. When compared with other energy generation technologies, solar PV systems present reduced environmental impacts: although the manufacture and disposal of PV panels and materials emit greenhouse gases (GHG), these are usually much lower than their fossil-fuel counterparts [3].

PV systems need energy and raw materials for manufacture, transportation, installation and final disposal. Each of these phases needs to be evaluated so that the environmental impacts can be estimated throughout the lifetime of the energy systems [4,5]. Advances in manufacturing processes and end-of-life scenarios (increased recycling, for example) can further reduce component-related emissions, consequently reducing the overall impact associated with PV systems. This increases the potential for using PV systems to generate low-carbon electricity and realize environmental benefits regarding avoided emissions [6].

The transition to low-carbon electricity generation has become a central focus of global energy policy, driven by the urgent need to mitigate climate change. This shift has been reinforced by international agreements such as the Paris Agreement, which commits signatory countries to reduce greenhouse gas emissions and promote sustainable energy systems [7]. Decarbonizing the electricity sector—through the adoption of renewable energy sources like solar, wind, and hydro—is essential to meeting global climate targets [8,9]. Consequently, national governments and regulatory bodies have implemented a range of policies and incentives to accelerate the deployment of low-carbon technologies, including feed-in tariffs, renewable portfolio standards, and carbon pricing mechanisms [10].

Brazil’s electricity matrix is predominantly composed of low-carbon energy sources, with a significant share derived from hydroelectric power, biomass, wind, and solar energy. According to the Brazilian Energy Research Office (better known by its acronym in Portuguese, EPE), more than 80% of the country’s electricity generation in recent years has originated from renewable or low-emission technologies, positioning Brazil as one of the global leaders in low carbon energy production [11]. This reliance on low-carbon energy sources is critical for meeting both international and domestic climate commitments. In particular, the Paris Agreement—ratified by Brazil in 2016—establishes legally binding objectives to limit global warming to well below 2°C above pre-industrial levels, with efforts to limit the increase to 1.5°C [7]. To support these targets, Brazil has developed national frameworks, including its Nationally Determined Contributions (NDCs) and the Ten-Year Energy Expansion Plan 2034, which outlines strategies for expanding renewable energy capacity, improving energy efficiency, and reducing GHG emissions [12]. These initiatives underscore the strategic role of low-carbon electricity in achieving climate resilience and sustainable development.

Increasing the efficiency of PV systems is highly relevant today because it impacts not only the performance and economics of the systems but also the sustainability and viability of projects. By focusing on reducing environmental impacts, higher efficiency means a smaller area is needed to install a PV system [13]. This is beneficial for land conservation and can reduce the environmental impact associated with the installation of large solar systems. Higher efficiency also means fewer panels are required, reducing the use of materials and resources in manufacturing and the amount of waste generated [14].

Enhancing the efficiency of solar PV systems is crucial for advancing solar energy adoption. Coating technologies, particularly anti-reflective and self-cleaning films, have shown significant promise in improving PV panel performance. Anti-reflective coatings can reduce light loss and increase the amount of light absorbed by PV panels [15], and self-cleaning coatings can reduce the need for manual maintenance and improve efficiency [16].

A study conducted in Morocco [17] demonstrated that an anti-reflective coating improved the annual performance ratio and energy yield of solar panels by 2% and 5.5%, respectively, under desert conditions. Additionally, there was a 2.7% reduction in the levelized cost of energy, indicating a more cost-effective energy generation process. The study of Ben Gouider Trabelsi et al. [18] explored the use of silicon dioxide (SiO₂) and zirconium dioxide (ZrO₂) as an anti-reflective coating for polycrystalline silicon solar cells and obtained minimized reflection losses and enhanced light absorption properties.

Regarding self-cleaning coatings, a polydimethylsiloxane/SiO₂ nanocoating demonstrated a 30.7% increase in panel efficiency compared to uncoated panels [19]. The coated panels exhibited reduced dust accumulation, leading to sustained energy output. Research on another nanocomposite coating revealed that it enhanced the durability, superhydrophilicity, and photocatalytic activity of the panels [20]. The coating maintained its effectiveness over a period of more than three years, resulting in approximately a 3% increase in power generation over 420 days.

Self-cleaning coatings have been in the research spotlight due to the easiness of manufacture and integration within solar energy systems [21]. Although suitable cleaning methods are used to regularly remove the dust deposited (e.g., manual or automatic cleanings), passive surface treatments decrease the losses associated with dust accumulation on the glass surface and power generation efficiency increases accordingly [22]. The losses associated with dust deposition on solar PV systems have been well studied, and can reach up to 70% [23]. The study of Zhao and Lu [24] verified that dust deposition on the coated glass sample was significantly lower compared with the bare glass sample, and the self-cleaning efficiency of super-hydrophilic coating reached more than 92%. The utilization of a spectral filter, employing ZnO-water nanofluid, was the focus of [25], who obtained an increase of 11.2% in electrical performance. Although the presence of dust decreased the outlet temperature of the filter, it led to a 66.79% improvement with the adoption of the self-cleaning method. A self-cleaning and transmission-enhancing multifunctional coating was fabricated through the sol-gel method by [26], and the results demonstrated that the coating exhibited superhydrophilic characteristics and outstanding anti-fogging performance. Also, there was a 1.24% increase in power generation, confirming the positive effects regarding dust and dirt elimination from the surface of PV panels and enhance power generation efficiency. A superhydrophobic composite coating with transparency, long-term durability and self-healing properties was developed by Xiang et al. [27], who verified that the maximum output power of the coating-covered photovoltaic panels increased by 2.03%. This represents a promising solution for the sustainable maintenance of solar infrastructures by integrating preventive self-cleaning with damage-responsive self-healing mechanisms in a synergistic manner.

Nevertheless, with the technological advances in solar coatings and PV panels, and considering their lifecycle, it is essential to understand the environmental repercussions. The current phase of technological development presents a critical window of opportunity to implement strategic adjustments that can significantly reduce potential negative impacts. At this early stage, innovations are still flexible and adaptable, making it far easier and more cost-effective to incorporate sustainable practices, ethical considerations, and safety measures before these technologies are scaled up and widely adopted in the global market [28].

Currently, one of the most widely used methodologies to analyze the environmental impact of products and energy systems is Life Cycle Assessment (LCA). LCA provides a comprehensive framework for evaluating the potential environmental impacts and associated liabilities of a product, process, or activity throughout its entire life cycle—from raw material extraction to end-of-life disposal [29]. By quantifying these impacts LCA enables meaningful comparisons between alternative products or processes. This evidence-based approach supports informed decision-making by highlighting trade-offs, identifying opportunities for improvement, and guiding the selection of more sustainable and responsible options. An additional criterion often employed to evaluate energy systems is the environmental payback. This concept refers to the duration required for the embedded GHG emissions—those generated during the manufacturing, transportation, and installation phases—to be offset by the system’s operational emissions savings [30]. Essentially, it represents the time needed for a technology to “amortize” its initial environmental debt through its ongoing, lower-impact operation.

Fonseca and Carvalho [30] assessed the greenhouse gas payback time (GPBT) of a wind turbine installed in the Brazilian Northeast. Their LCA revealed that the wind turbine had an emission factor of 0.0083 kg CO₂-eq/kWh and a GPBT of 276 days, underscoring the rapid environmental benefits of wind energy in the region [31] evaluated the environmental payback of a wind turbine across different locations in the Brazilian Northeast, concluding that the wind turbine could offset its manufacturing-related carbon emissions within the first two years of operation in all analyzed locations. The study of Chen et al. [32] reported that the GPBT of PV systems in China, the largest manufacturing and installation country, have decreased from 2.89 to 0.83 years from 2009 to 2019. In the USA, Grant et al. [33] reported on the GPBP for all 50 states considering the regional differences in solar potential and electricity mixes. The lowest GPBP was around 2 years for Colorado, Indiana, Missouri, New Mexico, Utah, West Virginnia, and Wyoming. The highest GPBT was 113 years for the state of Vermont due to its low carbon electricity grid, with 60% hydroelectricity 20% wood and 20% other renewables. The authors concluded with the remark that choosing solar PV locations with shorter GPBT will result in more pronounced environmental benefits and that LCA and GPBT should be combined to measure the sustainability and prioritization of solar PV systems compared to prioritizing using solar potential alone. On a broader perspective, Xie et al. [34] calculated the pollutant payback time of Chinese multi-crystalline photovoltaic production, including chemical oxygen demand, chloride, fluoride, ammonia gas, nitric oxide, sulfur dioxide, hydrogen chloride, hydrogen fluoride and carbon dioxide. The latter was 0.884 years, but most of the pollutants could be paid back within the expected lifetime of the PV system.

In the light of the above, the objective of this study is to present an environmental performance analysis concerning a 16.4 MW monocrystalline PV system installed in João Pessoa, Northeastern Brazil, which is one of the highest solar-irradiated cities in the world. The study presented herein employs LCA to quantify GHG emissions, empirical equations to calculate the electricity output of the system, and the GPBT concept. A state-of-the-art nano-silica-based self-cleaning coating has been investigated as a strategy to enhance PV system efficiency by mitigating particulate deposition and reducing water consumption associated with manual or mechanical cleaning. The performance of this advanced surface treatment is evaluated in terms of its potential to increase energy yield and lower the life cycle environmental impact of PV installations. A comparative analysis between uncoated (baseline) and coated PV modules is conducted to assess the extent to which such surface-engineering innovations can accelerate progress toward more sustainable solar energy systems, particularly in regions characterized by high solar irradiance and harsh environmental conditions.

This section begins with an explanation of the LCA procedure and detailed construction of the inventory for the reference (uncoated system). All equipment and materials employed are listed, along with the considerations made for the end-of-life scenario of the PV system. Then the calculation procedure for electricity production is thoroughly explained, followed by the payback concept. The section ends with the inventory for the coating.

Table 3 shows the carbon footprint for each part of the uncoated and coated PV systems. Due to the reduction in the number of panels in the coated system, all other components were adjusted accordingly (except for the administrative building).

Table 3 shows the installation accounted for the highest percentage of emissions from the PV system, with approximately 89% referring to the panels alone in the case of the uncoated system and 88% for the coated system. The frame, cables, etc. (which refers to the structure and grounding system) account for 4.65% and 4.87% of the uncoated and coated systems, respectively. Table 4 presents the contribution of some materials to the overall GHG emissions.

As for the contribution of O&M, it has 2.07% of total emissions, of which 1.11% refers to the replacement of panels during the 25 years of operation of the PV system. When adding this percentage to the value related to PV panels, approximately 90% of emissions refer to PV panels only.

Regarding the calculations of electricity generation, based on Eqs. (1)–(3) and climate data for João Pessoa, the result is 759,039.86 MWh in 25 years. The calculations consider the monthly averages (for each climatological variable), calculated based on daily data from the entire period of data available and evaluating the annual degradation. Fig. 1 shows the electricity production results.

From Fig. 1, it is observed that there is a sharper decrease in production between year 0 (zero) and year 1, as the degradation rate for the first year is higher. For the following years, an almost linear decline is shown.

Considering the Brazilian electricity mix and applying the method of Carvalho and Delgado [56], the GHG emissions associated with electricity consumption from the Brazilian electrical grid are 0.140 kg CO₂-eq/kWh consumed. With the electricity production (E_plant,tot25 = 759,039.86 MWh) and LCA results (Emissions_PV25 = 22,534,773 kg CO₂-eq), it is possible to calculate the emission factor of the PV system as 0.02969 kg CO₂-eq/kWh.

Fig. 2 shows the payback time for the uncoated PV system in João Pessoa. The point at which the line cuts the horizontal axis is the point that represents the system’s payback value for that location. The payback time of the uncoated PV system was 5 years and 1 day for João Pessoa.

The PV system benefits from a reduced installation area due to the enhanced efficiency achieved by applying a self-cleaning coating. Despite the reduced footprint, it maintains consistent electricity production throughout its lifetime, generating a total of 759,032.86 MWh. When dividing the overall emissions, Emissions_FV25 = 21,511,317 kg CO₂-eq, by the total electricity production, a carbon emission factor of FE_FV = 0.02834 kg CO₂-eq/kWh is obtained. The GPBT for the coated PV system in João Pessoa is 4 years, 1 month and 26 days (Fig. 3). The application of a self-cleaning coating reduced the environmental payback period by roughly four months compared to the uncoated system. Additionally, the enhanced efficiency achieved with the coating decreased the area required for system installation.

Schultz and Carvalho [43] obtained an environmental payback period of 5 years, 8 months, and 1 day. This result may have been influenced by variations in installation location and the use of earlier versions of methods and databases. Although the same PV system is considered, a different location is used. Also, the Ecoinvent database and the IPCC method used by Schultz and Carvalho [43] were from earlier versions of the Ecoinvent database and the 2013 IPCC method, while this study used the updated 2021 versions, ensuring more accurate and current data for the analysis. The energy equations used were also slightly different than those employed herein. Despite differences in the study results, due to each system’s specific characteristics, the environmental payback period is significanty shorter than the lifetime of the PV system. This fact reaffirms the environmental advantage of PV technologies, which is in line with international commitments established by agreements such as COP28, which aim to reduce GHG emissions.

Another parameter that can be applied to evaluate a renewable energy system is the lifetime avoided GHG emissions, expressed in t CO₂-eq/kW_p. Considering the lifetime avoided emissions for the uncoated PV system, these are 61,195,053.88 kg CO₂-eq, which leads to 61,195 t CO₂-eq/10,570 kW_p = 5.79 t CO₂-eq/kW_p. For the coated system, the avoided emissions are 62,988,155.92 kg CO₂-eq, which leads to 5.98 t CO₂-eq/kW_p.

Lamnatou et al. [58] obtained 9.1 t CO₂-eq/kW_p for a 150 kW_p PV plant with hydraulic storage installed in Catalonia, comparing the supplied electricity with the electricity mix of Spain. Gaiddon and Jedliczka [59] also presented lifetime avoided CO₂ emissions (not GHG emissions) for rooftop PV systems in several countries: 2.4 t CO₂/kW_p for France, 33.3 t CO₂/kW_p for Australia, 5.7 t CO₂/kW_p for Austria, 15.9 t CO₂/kW_p for Spain, and 0.2 t CO₂/kW_p for Switzerland. There is an extremely wide range of avoided emissions, which highly depend on the global irradiation of the site and the local electric grid composition.

Regarding the concept of GHG payback, from Eq. (5) it can be seen that it depends strongly on the emissions associated with the local supply of electricity. In Brazil, there have been slight fluctuations in the composition of the National electricity mix in recent years, which have led to changes in GHG emissions. Fig. 4 shows the GHG emissions associated with the Brazilian national electric grid for 2019–2023, based on its composition of generation technologies.

Although the concept of GHG payback is well-established, an adaptation can be implemented to accommodate energy transition efforts and better represent changes in electricity mixes throughout time. Fig. 4 illustrated that the emission factor of the Brazilian electric grid has changed considerably in recent years. In 2023, the emission factor was 0.140 kg CO₂-eq/kWh, whereas in 2021, it was notably higher at 0.268 kg CO₂-eq/kWh. This would lead to a markedly different environmental payback time, reducing it by approximately two years when considering the lower emission factor of 2023.

Future discussions could explore the potential benefits of increased solar radiation in Northeastern Brazil due to the intensification of climate change, and the association of such findings with air temperature, as pointed by Santos et al. [60]. Also, additional parameters can be investigated to enhance further the results obtained herein, as Ferreira et al. [61] proposed a method to rank the top locations for wind, solar and hybrid electricity generation potential. The IP-PB method [61] can be applied to different regions of the world for the same purpose. A detailed cost-benefit analysis could also be an interesting complementary study, regarding how the initial investment costs for the coating compare to the long-term savings from reduced cleaning frequency and increased efficiency over the system’s 25-year lifespan.

In urban settings where space is at a premium, the reduction in required PV panel area due to the application of solar coatings has several planning and land-use implications. Because smaller arrays can be installed for the same output, building rooftops can host smaller PV systems to meet energy demands, leaving additional space for other uses (e.g., green roofs, recreational areas, HVAC equipment). Also, some rooftops can integrate PV with rooftop farming, gardens, or shaded seating, supporting multifunctional urban infrastructure. An interesting study by Montealegre et al. [62] has characterized building rooftops with LiDAR and Cadastral data, to assess the potential of food-energy-water systems on the rooftops of buildings in Spain. If less PV panel area is required, rainwater harvesting and food production alternatives can also be implemented, contributing to the concept of sustainable and intelligent cities.

It is also important to consider regional variability when assessing the effectiveness of self-cleaning solar coatings. In desert regions, where dust often contains larger, abrasive particles like silica, coatings will wear out faster or become less effective [63]. In industrial [64] or coastal regions [65], where particles can include soot, salt, or heavy metals, the adhesion and chemical interaction with coatings can differ significantly. In coastal regions there is also the effect of humidity [66]. Frequent, moderate rainfall can aid the cleaning function but in arid or low-rainfall areas, the cleaning action is minimal, potentially leading to long-term accumulation and reduced coating efficacy. Heavy rains, though less frequent, can sometimes wash away loose dust but may also lead to spotting or streaking if not uniformly distributed [67]. Regarding the limitations in extrapolating results, a coating that performs well in a temperate, high-rainfall area may be ineffective in a dry, dusty environment. Also, durability can vary, as the coating lifespan and cleaning performance can degrade faster in harsher climates due to abrasion or UV exposure. There could also be maintenance differences, and in some areas, periodic manual cleaning may still be necessary to maintain optimal performance. Also, regarding real world settings, lab or pilot studies may not account for cumulative environmental stressors experienced over a 25-year system lifespan in different regions.

Considering that some regions are more sensitive or vulnerable to climate change, future climate trends can affect the predictions of energy generation. This has been investigated by Medeiros et al. [50], who verified the influence of climatic variability on the electricity generation potential by renewable sources in the Brazilian semi-arid region. In their study, Ref. [50] showed that annual solar PV electricity production remained relatively stable over the years despite rising temperatures, possibly due to slight reductions in cloud cover offsetting negative impacts. However, production was consistently higher when analyzing only the first 10 years of the data, suggesting a subtle downward trend that could become more significant in the future and should be accounted for in PV system design.

The adoption of coated PV panels can play a pivotal role in enhancing the efficiency and longevity of solar installations. In regions like Brazil, where solar energy potential is abundant, optimizing PV system performance is crucial for meeting renewable energy targets. The Brazilian installed solar capacity has reached 50 GW in 2024, according to the Brazilian Solar Energy Association [68], accounting for 22.2% of Brazil’s total installed electricity capacity, making it the country’s second-largest generation source. The widespread adoption of self-cleaning coated PV systems could further accelerate this growth by enhancing system performance and reducing operational costs. This would contribute to a more sustainable and resilient energy matrix, aligning with Brazil’s NDC commitments. Brazil has committed to reducing its net greenhouse gas emissions by 59% to 67% by 2035, compared to 2005 levels, according to its Nationally Determined Contribution (NDC) submitted to the United Nations Framework Convention on Climate Change (UNFCCC) [69]. Achieving these rather ambitious goals necessitates significant advancements in renewable energy deployment, particularly solar PV systems; and as shown herein, solar coatings can improve energy production by PV panels and even reduce maintenance costs due to the decreased accumulation of dust and other particulate matter.

While self-cleaning coatings can offer technical and environmental benefits, the social implications can significantly influence how widely and effectively they are adopted. This is an important and often overlooked aspect of technological adoption. There could be an impact on local maintenance job markets. The application of solar coatings on PV panels will lead to a decrease in the frequency of manual cleaning [70,71], which could reduce the demand for maintenance labor, particularly in more vulnerable regions where PV cleaning jobs are a significant source of local employment [72]. This could create concerns about job displacement among workers currently employed in PV maintenance, especially in rural or developing areas. Nevertheless, this could lead to a demand for new skills (e.g., installation and monitoring of coated systems), offering opportunities for upskilling and more specialized employment. Overall, the use of solar coatings can be a positive influence: if framed as a way to reduce water use, lower maintenance costs, and improve energy access, adoption may increase—especially in water-scarce or remote areas. In sum, for self-cleaning PV coatings to contribute effectively to national energy and climate goals, policies should address not only technological performance but also the social and economic dimensions of adoption.

This paper presented a detailed life cycle inventory for a self-cleaning coating applied to PV panels to improve performance. The study focused on a 16.4 MW solar PV system, comparing the GHG emissions of both the uncoated and coated systems. The PV system was found to generate 759.04 GWh of electricity over its 25-year lifetime. The uncoated system resulted in 22,534,773 kg CO₂-eq of emissions, while the coated system emitted 21,511,317 kg CO₂-eq. These figures lead to emission factors of 0.02969 kg CO₂-eq/kWh for the uncoated system, and 0.02834 kg CO₂-eq/kWh for the coated system. The payback time of the uncoated PV system was approximately 5 years, whereas the coated system’s payback time was 4 years, 1 month and 26 days.

It was demonstrated that the PV system benefited from an increase in efficiency, due to the coating, which also led to a reduction in the required area for installation. Additionally, the results demonstrated that PV systems have the potential to mitigate climate change, being a promising tool for reducing environmental impacts. When integrated into broader initiatives aimed at reducing environmental impacts and fostering sustainable urban development, PV systems offer strategic advantages in advancing sustainability.