Solar panels experience significant power fluctuations during cloudy and rainy weather, primarily due to cloud cover causing a sharp drop in sunlight intensity, changes in spectral distribution, and frequent shifts in localized shadows. These fluctuations not only affect grid stability but can also reduce energy efficiency. To smoothly control output power, a comprehensive solution needs to be built from four dimensions: energy storage system configuration, intelligent control algorithms, equipment optimization, and system synergy.
Energy storage systems are the core means of smoothing power fluctuations. During cloudy and rainy weather, the output power of solar panels may fluctuate significantly in a short period as clouds move. In such situations, battery energy storage systems can absorb or release energy through rapid charging and discharging to fill the power gap. For example, when output power drops sharply, the energy storage system immediately releases electrical energy to maintain grid load balance; when output power recovers, excess energy is stored for later use. Furthermore, supercapacitors, due to their high charge and discharge rates, can assist battery systems in coping with high-frequency fluctuations, while flywheel energy storage is suitable for long-term, low-power smoothing. By coordinating multiple types of energy storage devices, power fluctuation requirements at different time scales can be covered.
Intelligent control algorithms are a key technology for achieving power smoothing. Control strategies based on low-pass filtering principles can effectively filter out high-frequency fluctuation components. This algorithm calculates the average power within a set time window and uses this value as the output target, thereby eliminating short-term fluctuations. For example, a first-order Butterworth low-pass filter can adjust its smoothing effect according to the filtering time constant; a larger time constant results in a smoother output curve, but requires greater energy storage capacity. Furthermore, combining power prediction technology allows for advance adjustment of the energy storage system's charging and discharging strategies, further enhancing the smoothing effect. Machine learning algorithms analyze historical data and environmental factors to predict future power change trends, enabling the system to proactively adjust.
Optimized equipment design can improve the adaptability of solar panels on cloudy and rainy days. Bifacial modules can increase power generation on cloudy and rainy days by capturing reflected light from the ground. Experiments show that monocrystalline silicon bifacial modules can achieve a 75% utilization rate of diffused light, significantly higher than single-sided modules. Simultaneously, modules with hydrophobic coatings on their surfaces reduce rainwater adhesion, preventing a decrease in light transmittance due to water accumulation. For example, a nano-hydrophobic coating allows water droplets to form perfect spheres and roll off, reducing residual water on the panel surface and maintaining power generation efficiency. Furthermore, optimizing the installation angle and orientation of components maximizes the reception of diffused light and reduces power loss caused by improper angles.
System coordinated control is essential for achieving smooth power output. In microgrids or distributed generation systems, solar panels need to operate in conjunction with other energy devices. For example, they can complement wind power generation, using the stability of wind energy to compensate for the intermittency of solar power; or they can be linked with diesel generators to provide backup power during extreme cloudy or rainy weather. Real-time monitoring of the status of each device through an energy management system (EMS) and dynamic adjustment of power distribution ensures stable overall system output. In addition, smart inverters can further reduce the impact of power fluctuations on the grid by dynamically adjusting operating parameters, such as adjusting output voltage and frequency according to sunlight intensity and grid demand.
The application of power conditioning equipment can improve power quality. Dynamic voltage regulators and static var compensators provide buffering, reducing voltage and frequency deviations caused by power fluctuations. For example, when the output power of solar panels drops sharply, dynamic voltage regulators can quickly increase the voltage to prevent equipment shutdown due to undervoltage; while static var compensators maintain a stable grid power factor by compensating for reactive power. These devices, in conjunction with energy storage systems and intelligent control algorithms, can construct a multi-level power smoothing system.
In the long term, technological innovation and material upgrades will continue to optimize power smoothing effects during cloudy and rainy days. New perovskite materials achieve a 28% conversion rate for ultraviolet light and can still operate even under rain cloud cover, increasing power generation on cloudy and rainy days. Graphene rain-generating batteries generate electricity through the reaction of raindrop salts with graphene, achieving a laboratory efficiency of 6.5%, providing new ideas for rainy day energy utilization. Furthermore, intelligent cloud-tracking systems use AI to predict cloud movement and dynamically adjust component angles to capture optimal diffused light, demonstrating improved power generation during rainy days in real-world testing. These technological breakthroughs will gradually reduce the impact of cloudy and rainy days on solar panel output.
From a policy and market perspective, subsidies for energy storage equipment, tax incentives, and improved grid connection standards can promote the widespread adoption of power smoothing technologies. For example, some regions offer subsidies for photovoltaic projects installing energy storage systems, reducing initial investment costs for users; while strict grid connection power fluctuation standards force companies to adopt smoothing control technologies. As technology matures and costs decrease, power smoothing control will become a standard feature of solar panel systems, facilitating the large-scale application of renewable energy.
