Evaluating solar photovoltaic power efficiency based on economic dimensions for 26 countries using a three-stage data envelopment analysis

This paper proposes a new concept for solar photovoltaic (PV) power efficiency and explores a new direction by considering such efficiency at the national level and from a macro perspective. Solar PV power efficiency is defined in this study as a measure of investment in, and management and development of, solar PV generation in each country, along with the efforts made to increase such investment and implement development measures. Solar PV power efficiency is considered instrumental in addressing climate change and achieving sustainable development. Therefore, its assessment is of interest to the vast majority of economies. This study used economic dimensions to analyze solar PV power efficiency and its influencing factors in 26 countries from 2000 to 2020 in a three-stage data envelopment analysis. The results show that, first, the overall solar PV power efficiency of the 26 countries is 0.762, which leaves significant room for improvement, and that most of the countries with high average solar PV power efficiency are high-income. Second, increasing GDP per capita and lowering carbon dioxide emissions contribute to higher solar PV power efficiency. The proportion of the urban population in the total population also impacts solar PV power efficiency. Third, the extent to which external environmental variables affect solar PV power efficiency varies across countries. The 26 countries considered generally had higher average solar PV power efficiency in the third stage than in the first stage, indicating that external environmental variables can lead to an underestimation of solar PV power efficiency. The range of difference varies by country; Mexico, Morocco, Australia, Japan, and South Korea saw the most significant increases in solar PV power efficiency, all exceeding 0.3. In addition, this study makes several measures to improve solar PV power efficiency. Overall, the findings contribute to understanding the trends and influencing factors of solar PV power efficiency in 26 countries and can provide a new calculation method for studying solar PV power efficiency.