## 4 Analysis and Interpretation of Results
### Correlation Links Between Individual Production Sources and Residual Load
#### 4.3.2 Analysis of the Fracture Market  
The French electricity system is characterised by a high share of nuclear power and a relatively low penetration of wind and solar compared to a country like Germany. This structure is also reflected in the correlations between RES generation, residual load and electricity prices.  
Overall, correlations between wind and other variables are low:  
- Wind/Residual Load: r = +0.07  
- Wind/Price: r = \(-\)0.10  
The weak positive correlation of wind with residual load suggests that wind generation in France only moderately affects residual load. This effect can be attributed not only to the limited capacity of wind power plants, but also to the dominance of stable nuclear generation, which minimises the impact of short-term changes in wind conditions on the demand for other resources. The negative but weak correlation between wind generation and prices confirms that the impact of wind on pricing is limited and less pronounced than in countries with higher RES penetration.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Wind/Solar** & **Wind/Residual Load** & **Wind/Price** & **Solar/Residual Load** & **Solar/Price** & **Residual Load/Price** \\ \hline Germany & \(-\)0.15 & \(-\)0.49 & \(-\)0.41 & \(-\)0.16 & \(-\)0.09 & 0.82 \\ France & \(-\)0.14 & 0.07 & \(-\)0.10 & \(-\)0.09 & \(-\)0.04 & 0.58 \\ Poland & 0.01 & \(-\)0.32 & \(-\)0.14 & \(-\)0.01 & \(-\)0.01 & 0.56 \\ Slovakia & - & - & - & 0.00 & 0.07 & 0.61 \\ Czech Republic & \(-\)0.16 & 0.11 & \(-\)0.27 & \(-\)0.13 & 0.03 & 0.55 \\ Estonia & \(-\)0.06 & \(-\)0.14 & \(-\)0.13 & \(-\)0.03 & 0.06 & 0.58 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Correlation across countries.  
Correlations with solar generation are even weaker:  
* Solar/Residual Load: r = \(-\)0.09
* Solar/Price: r = \(-\)0.04  
The weak negative correlation between solar generation and residual load shows that solar generation has some, but small, direct effect on the decline in the need for conventional generation. The correlation between solar and electricity prices is almost zero and even goes positive in some years (e.g., in 2022 Solar/Price = +0.08), which may be due to specific seasonal or meteorological conditions.  
The most significant and consistent relationship is the correlation between residual load and electricity price:  
* Residual Load/Price: r = +0.58 (total)  
This relationship is expected as higher residual demand increases the need to deploy more expensive resources and hence prices. However, in some years there is a decrease in this relationship (e.g., in 2022 Residual Load/Price = +0.15), which may be related to increasing network flexibility, more cross-border flows or changes in demand patterns.  
Between 2023 and 2025 there is a significant change in correlation patterns:  
* Wind/Solar: r = \(-\)0.19 (2023), r = \(-\)0.18 (2024), r = \(-\)0.18 (2025)
* Wind/Residual Load: r = \(-\)0.18 (2023), r = \(-\)0.09 (2024), r = \(-\)0.43 (2025)
* Wind/Price: r = \(-\)0.34 (2023), r = \(-\)0.19 (2024), r = \(-\)0.42 (2025)  
The negative correlations between wind and residual load, as well as between wind and price, are deepening during this period. In particular, there is a sharp increase in the absolute value of the negative correlation in 2025 (Wind/Residual Load = \(-\)0.43; Wind/Price = \(-\)0.42). This trend suggests an increasing influence of wind on the decline in residual demand and prices, which may be due to faster wind capacity development, technological changes or enhanced flexibility of the electricity system.  
Also significant is the deepening negative correlation between solar generation and price in 2024 and 2025:  
* Solar/Price: r = \(-\)0.34 (2024), r = \(-\)0.35 (2025)  
This development shows that solar generation is also starting to have a more noticeable impact on market prices, especially during sunny hours with low demand.