# Progress in Improving Photovoltaics Longevity
## 4 Results
### PV Longevity Improvement
#### 4.4.1 Knowledge Improvement  
The first commercial PV modules, back in the 1980s, had an estimated operational lifetime of 10 to 15 years [146; 147]. In the 1990s, the average lifetime was increased to around 20 years, mainly due to the transition from mono(poly)crystalline Si to thin-film materials, such as CIGS (Copper Indium Gallium Selenide), CdTe (Cadmium Telluride) and amorphous silicon (Si) [148]. This technological leap, in combination with advances in manufacturing protocols and enhanced encapsulation materials, upgraded the durability of PV modules. The establishment of testing procedures in the early 2000s for the evaluation of the reliability of PV modules led to a lifetime of 20 to 25 years [149; 150], as the majority of degradation mechanisms, such as environmental stress factors, could be detected at an initial phase. In the 2010s, the PV industry witnessed huge improvements and innovations, with the introduction of bifacial modules, perovskite materials, and enhanced anti-reflective coatings, which promised improved efficiency and lower degradation rates. These breakthroughs raised the expected lifetime of the PV modules from 25 to 30 years [151; 152]. Nowadays, PV manufacturers constantly attempt to further expand the boundaries of the module's lifetime. Higher efficiency and durability are ensured by data analysis, field and remote real-time monitoring, as well as maintenance procedures. The progress made so far, as well as the advancements that are yet to be achieved, aim at extending the PV module's lifespans into the 30-40-year range [153; 154]. In Tables 7 and 8, a synopsis of photovoltaic systems' lifetime data over time is presented, based on literature sources and references and warranty data from different manufacturing companies [155], respectively. In Figure 5, the data for PV module lifetime from Tables 7 and 8 in a common diagram are depicted. The time axis is divided into decades, and the selected data points are depicted with corresponding error bars in both horizontal and vertical axes. The increasing trend of the curves reflects the ongoing development efforts and research focused on PV technology. The two curves have good correspondence, and now the scientific community is eager to observe whether the projected PV lifetime will live up to its expectations and break the 30-40-year barrier. Despite progress and advancements, numerous challenges along with scientific gaps remain, indicating the areas where both the available bibliography and the scientific research are incomplete. The longevity of a PV module has great expansion potential under the prism of knowledge improvement and overall design, which could guarantee enhanced cost-effectiveness and sustainability. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Decade** & **Lifetime According to Literature [Years]** & **References** \\ \hline
1980–1990 & 10–15 & [146; 147] \\
1990–2000 & 15–20 & [148] \\
2000–2010 & 20–25 & [149; 150] \\
2010–2020 & 25–30 & [151; 152] \\
2020–2030 & 30–35 (the range 30–40 years is the desirable goal) & [153; 154] \\ \hline \hline \end{tabular}
\end{table} 
Table 7: The increment in PV module’s lifetime over time, according to literature sources. Detailed insight and a full understanding of some degradation mechanisms, such as PID, TID, UV exposure, and LID, are still lacking. The key to improving PV module longevity is identifying these degradation processes and employing appropriate mitigation strategies. In Table 9, a comprehensive overview of the incomplete knowledge of these degradation mechanisms is presented, while several material advancements for their mitigation are also highlighted. \begin{table}
\begin{tabular}{c c c} \hline
**Decade** & **Warranty PV Lifetime Data [Years]** & **References** \\ \hline
1980–1990 & 5–15 & \\
1990–2000 & 15–25 & \\
2000–2010 & \(\sim\)25 & \\
2010–2020 & 25–30 & \\
2020–2030 & 30–35 & \\ \hline \end{tabular}
\end{table} 
Table 8: The increment in PV module’s lifetime over time, according to warranty data from different manufacturing companies [155].