Empirical Results
The empirical analysis of this paper adopts Stata15.0 statistical software to perform fixed effect regression analysis, with the purpose of evaluating the overall impact of explanatory variables including core explanatory variables and control variables on regional GDP (Y). Through detailed regression analysis, the model shows that after all control variables are included,
The F-test value of 68.82 (
p < 0.01) indicates that the regression model as a whole is statistically significant, meaning that the group of explanatory variables jointly explain variations in regional GDP at a high level of confidence. This does not imply individual causality but suggests that the model captures meaningful associations between the independent variables and regional economic outcomes. As shown in
Table 8 below. In addition, the pseudo-judgment coefficient (R
2) of the model is 0.8622, which means that the variables included in the model can explain 86.22% of the variation in regional GDP, while the remaining 13.78% of the variation has not been explained by the model. This indicates that there may be other important variables or external factors not considered in the model, which may also have an impact on regional GDP. Despite this unexplained variation, the overall significance of the model ensures the validity and applicability of the chosen set of variables in explaining regional GDP.
Firstly, according to the regression analysis in
Table 8 above, regarding the influence of the core explanatory variable photovoltaic power generation (X1) on the regional GDP (Y) of each region in Qinghai Province, we observe that the regression coefficient of photovoltaic power generation is 1.727, which has a significant positive impact and is statistically significant at the level of 5%. This shows that when other conditions remain unchanged, each additional unit of PV power generation in each region of Qinghai Province will increase the regional GDP by 1.727 units on average. The reason may be that with the gradual rise and further development of photovoltaic power generation, photovoltaic power generation drives the scale of related industries to gradually increase, and then drives the improvement of local fiscal revenue and gross national product. In addition, the development of large-scale PV may be closely related to regional policy support, technological progress, and market demand growth, which together act on the upgrading of regional economic activities. With the expansion of the photovoltaic construction scale, the increase in photovoltaic power generation, and the gradual reduction in cost, photovoltaic power generation will become a key driving force to promote the optimization of economic structure and green and low-carbon development of Qinghai Province.
Secondly, in terms of the influence of the control variables of total import and export trade (X2) and fixed asset investment growth rate (X3) on the GDP of each region in Qinghai Province, this paper analyzes the influence of the two variables of total import and export trade (X2) and fixed asset investment growth rate (X3) on the GDP of each region in Qinghai Province. The regression coefficients of the total import and export trade volume and the growth rate of fixed asset investment are 0.674 and 0.487, respectively. With every unit increase in the total import and export trade of each region in Qinghai province, the GDP of each region in Qinghai province will increase by 0.674 units accordingly. However, the regression coefficient of the growth rate of fixed asset investment fails to pass the significance test, indicating that the growth rate of fixed asset investment is not the core cause of the changes in regional GDP. Thirdly, the regression coefficients of the influence of the total fiscal revenue (X4) and the local public budget revenue (X5) on the regional GDP of Qinghai Province are 1.156 and 1.658, respectively. It shows that the regression results of the variables of total fiscal revenue (X4) and local budget revenue of public finance (X5) are significant, that is, both total fiscal revenue (X4) and local budget revenue of public finance have a significant positive impact on the GDP of all regions in Qinghai Province. Moreover, the influence degree of the local public finance budget revenue on the regional GDP of Qinghai Province is greater than that of the total fiscal revenue on the regional GDP of Qinghai Province. Finally, the influence of the control variable, the number of female employees in non-private units (X6), on the GDP of each region in Qinghai Province is analyzed. The regression coefficient of the number of female employees in non-private units is significantly positive, indicating that the higher the number of female employees in non-private units is, the higher the GDP of each region is.
In order to explore whether there are regional differences in the impact of provincial photovoltaic power generation on regional economic development, eight prefecture-level cities in Qinghai Province are divided into developed regions and underdeveloped regions according to the level of economic development and regional distribution, as shown in
Table 9 below:
In order to further explore the impact of the level of regional economic development on the analysis results, this study divides the samples into two sub-samples according to the level of regional economic development: developed regions and underdeveloped regions. This subsample regression analysis method allows us to examine in detail how the level of economic development moderates the relationship between PV generation and gross regional product. Regression 1 and Regression 2 in
Table 10 and
Table 11 below present the results of the regression analysis for developed and less developed regions, respectively. This sub-sample regression analysis can not only reveal the difference in the impact of photovoltaic power generation on regional GDP under different economic development backgrounds but also help to formulate more accurate regional economic policies. For example, if the economic benefits of photovoltaic power generation are found to be more significant in less developed regions, policy makers may consider increasing support for photovoltaic projects in these regions to promote rapid local economic development. On the contrary, if the contribution of PV to economic growth is greater in developed regions, it may be necessary to further optimize the energy mix and improve the application efficiency of PV technology in these regions. Through this sub-sample analysis, the regional economic effects of PV power generation can be more accurately identified and utilized to provide a basis for sustainable development policies.
According to the results of heterogeneity analysis in
Table 10 and
Table 11, the positive impact of photovoltaic power generation on regional economic development is significantly different between developed and less developed regions. The regression coefficients of the core explanatory variable photovoltaic power generation in regression result 1 (developed regions) and regression Result 2 (underdeveloped regions) are 2.098 and 0.864, respectively, which indicates that each unit increase in photovoltaic power generation in developed regions can increase regional GDP by 2.098 units, while in underdeveloped regions, The same increase results in an increase of only 0.864 units in the gross product. This indicates that the economic utilization efficiency of PV energy is higher in more economically developed regions, which may benefit from a more mature market structure, more advanced technical support, and more efficient energy utilization strategies. In general, photovoltaic power generation has a significantly positive effect on regional economic development, in which provincial photovoltaic power generation in developed regions has a greater impact on regional economic development and provincial photovoltaic power generation in underdeveloped regions has a lower impact on regional economic development.
The control variable analysis further reveals other drivers of regional economic development. In developed regions, the growth rate of fixed asset investment significantly contributed to economic growth, which may reflect that infrastructure and capital investment remain key drivers of economic growth in more mature economies. However, in less developed regions, although the growth rate of fixed asset investment does not have a significant positive economic impact, this may indicate that the economic growth of these regions depends more on other factors, such as labor cost advantage, natural resource utilization, or government policy support. Therefore, according to the results of the analysis, the PV development policy should be customized according to the economic development level and market conditions of the region to ensure the maximum benefit of PV energy investment. For developed regions, the energy structure should be optimized and the application efficiency of photovoltaic technology should be improved. For less developed regions, more attention may be needed to infrastructure construction and improve technical support and financial input for local photovoltaic projects to improve energy efficiency and economic growth potential in these regions.
In order to further explore whether there is a nonlinear relationship between photovoltaic power generation and regional economic development, the quadratic term of photovoltaic power generation is introduced into the model (photovoltaic power generation * photovoltaic power generation) to conduct regression analysis on the data again. The regression results are shown in
Table 12 below.
According to the regression coefficients of the quadratic term and photovoltaic power generation, it can be seen that the regression coefficients of the two variables are significant, which indicates that photovoltaic power generation has a significantly positive effect on regional economic development within a certain range. When the value of photovoltaic power generation is greater than a certain range, photovoltaic power generation has a significantly negative effect on regional economic development. The critical value is (b/−2a) = (4.982/2/0.0611) = 40.77, which indicates that when the photovoltaic power generation is less than 40.77, the photovoltaic power generation has a significantly positive effect on regional economic development. When the photovoltaic power generation is greater than 40.77, the photovoltaic power generation has a significantly negative effect on regional economic development.
Further explore the results of regional differences in regional economic development according to the interaction item photovoltaic power generation * photovoltaic power generation, as follows:
According to the analysis results in
Table 13 and
Table 14, the interaction term and photovoltaic power generation in regression result 1 (in more developed regions) are not significant, which means that there is no inverted U-shaped relationship between photovoltaic power generation and regional economic development. The interaction term and photovoltaic power generation in the regression results (in underdeveloped areas) are significant, which means that there is an inverted U-shaped relationship between photovoltaic power generation and regional economic development, and the critical value is (b/−2a) = (48.19/2/11.6) = 2.08.