# Progress in Improving Photovoltaics Longevity
## 5 Discussion
For example, at the moderate climate of Brighton with global horizontal irradiation of 1195 kWh/m\({}^{2}\)/year, the correlation coefficient between PV output, absolute, or normalized to incident radiation and low humidity increase has not been found significant [214]. However, humidity is an important parameter of solar module degradation. Intense degradation in hot and humid areas with high humidity and temperature has been observed for c-Si modules [215]. As moisture infiltrates into the PV panel, EVA, the most common encapsulant for c-Si, is hydrolyzed with acetic acid by-product, causing corrosion of silver grids and an increase in the Rsh of PV modules. Also, sticky and cementing dust layers are created on PV surfaces in high relative humidity conditions, resulting in soiling and lower output, which can be recovered by proper cleaning methods. Therefore, long-term PV exposure in a humid atmosphere can lead to the corrosion of the modules due to moisture ingress into the solar cell. Successful mitigation of photo-degradation, particularly due to UV exposure, is crucial for the long-term stability of PV systems. To reduce the photo-degradation rate, an optimization of the material bandgap of the cells for the minimization of UV light absorption is suggested. Advanced materials with a tailored bandgap for the absorption of visible and IR light and the reflection or inhibition of UV radiation are essential. Additionally, glass layers or UV-blocking coatings offer a combination of enhanced protection against harmful UV rays and maintenance of solar cells' integrity. The application of these strategies can prolong the expected lifetime of PV modules and ensure their quality performance, particularly in areas with intense UV exposure. Another ongoing challenge is adopting a holistic approach to PV systems in terms of cost-effectiveness and reliability. Material selection and innovative manufacturing technologies are extremely complicated, and their interaction and seamless integration with the adjacent module components should be properly evaluated. The current focus in the PV technology sector is on balancing cost-effectiveness. Prioritizing advanced technology that exhibits either lower cost at the same efficiency level or higher efficiency at the same cost is vital for ensuring PV longevity [216]. Achieving a longer lifespan of PV modules can also limit their environmental impact to a great extent by diminishing the need for new module production for replacement purposes. A longer lifetime will be proven an environmentally friendly investment by significantly reducing module recycling and PV waste. As PV technology continues to evolve and new materials are introduced, a detailed understanding and evaluation of the module's reliability remains crucial. The constant emphasis on testing procedures and identification of potential failure modules is the key to ensuring that technological breakthroughs enhance the longevity of solar energy systems. The implementation of the PV reliability learning cycle, depicted in Figure 8, is a standard procedure for increasing the PV lifespan and improving their longevity [153]. The cycle starts with the observation and diagnosis of PV product operations in the field, followed by failure analysis and modeling to understand the degradation mechanisms. This leads to the development of physical models, new characterization and prognostic tests, and the design of new products. However, the long period of each learning cycle does not coincide with the short-length period of new cells and modules and necessitates reliable accelerated tests, advancing monitoring methods with sensible and embedded sensors, and feedback loops of big data analysis with the help of artificial intelligent methods. Although the operational guarantee of current photovoltaics is 30 to 35 years, PV modules continue to operate at high fractions of their expected outcome and are economically viable even after this period [37].