Introduction to Four Application Scenarios of PV + Energy Storage Systems
PV + energy storage, simply put, combines solar power generation with battery storage. As grid-connected PV capacity continues to increase, its impact on the power grid grows, creating greater growth opportunities for energy storage.
PV combined with energy storage offers numerous benefits. First, it ensures more stable and reliable power supply. The energy storage device acts like a large battery, storing excess solar electricity. When sunlight is insufficient or electricity demand is high, it can provide power, ensuring an uninterrupted electricity supply.
Second, PV plus energy storage makes solar power more economical. Through optimized operation, it enables higher self-consumption of electricity, reducing the cost of purchasing power from the grid. Moreover, the storage device can participate in ancillary service markets to generate additional revenue. The application of energy storage technology makes solar power generation more flexible, meeting various electricity demands. Simultaneously, it can work with virtual power plants to achieve complementary multi-energy integration and coordinated supply and demand.
Unlike pure grid-connected power generation, PV energy storage requires adding storage batteries and battery charging/discharging devices. Although this increases the initial cost, it significantly broadens the application scope. Below, we introduce four PV + energy storage application scenarios based on different applications: Off-grid PV energy storage, Grid-tied with backup PV energy storage, Grid-tied PV energy storage, and Microgrid energy storage system scenarios.
1. Off-grid PV Energy Storage Application Scenario
Off-grid PV energy storage power generation systems can operate independently without relying on the grid. They are widely used in remote mountainous areas, non-electrified regions, islands, communication base stations, streetlights, and other locations. The system consists of a PV array, an integrated PV inverter-charger controller, a battery bank, and electrical loads. The PV array converts solar energy into electricity during sunlight hours, powering the loads through the integrated inverter-charger and charging the battery bank. During periods without sunlight, the battery bank supplies power to AC loads via the inverter.
Off-grid PV power generation systems are specifically designed for areas without grid access or experiencing frequent power outages, such as islands and ships. These systems do not depend on the main grid, operating on a “store while use” or “store first, use later” mode, essentially serving as a critical power source. For households in non-electrified or frequently blackout areas, off-grid systems offer strong practicality.
2. Grid-tied with Backup PV Energy Storage Application Scenario
Grid-tied with backup PV energy storage systems are widely used in areas experiencing frequent power outages, or where self-consumed PV power cannot be fed back into the grid (no net metering), places with high self-consumption electricity tariffs, or where peak electricity prices are significantly higher than off-peak prices.
The system comprises a PV array formed by solar modules, a solar grid-tied/off-grid hybrid inverter, a battery bank, and loads. The PV array converts solar energy into electricity during sunlight hours, powering the loads through the solar hybrid inverter and charging the battery bank. During periods without sunlight, the battery bank supplies power to the hybrid inverter, which then powers the AC loads.
Compared to grid-tied systems, hybrid systems add charge/discharge controllers and batteries, increasing system costs by approximately 30%-50%, but they offer a broader application scope. Firstly, they can be set to output at rated power during peak electricity price periods, reducing electricity bills. Secondly, they can charge during off-peak periods and discharge during peak periods, profiting from the peak-valley price difference. Thirdly, when the grid fails, the PV system continues operating as a backup power source; the inverter can switch to off-grid mode, allowing the PV and batteries to power the loads via the inverter. This scenario is currently more widely applied in developed countries overseas.
3. Grid-tied PV Energy Storage Application Scenario
Grid-tied energy storage PV power generation systems typically operate using an AC-coupled approach with PV + storage. The system can store excess generated electricity, increasing the self-consumption ratio. PV is applied in scenarios such as ground-mounted PV with storage and commercial/industrial PV energy storage. The system consists of a PV array formed by solar modules, a grid-tied inverter, a battery bank, a Power Conversion System (PCS) for charging/discharging, and electrical loads. When solar power is less than the load power, the system is powered by both solar energy and the grid. When solar power exceeds the load power, part of the solar energy powers the load, while the rest is stored via the controller. Simultaneously, the energy storage system can be used for peak-valley arbitrage, demand charge management, and other scenarios, adding revenue streams.
As an emerging clean energy application scenario, grid-tied PV energy storage systems are receiving significant attention in China’s new energy market. This system integrates PV generation, energy storage devices, and the AC grid, achieving efficient utilization of clean energy. It offers several major advantages:
Improves PV Utilization: PV generation is significantly affected by weather and geographical conditions, leading to generation fluctuations. Energy storage devices can smooth the output power of PV generation, reducing the impact of fluctuations on the grid. Additionally, storage can provide energy to the grid under low-light conditions, enhancing PV utilization.
Enhances Grid Stability: Grid-tied PV energy storage systems enable real-time grid monitoring and regulation, improving operational stability. During grid fluctuations, the energy storage device can respond rapidly, providing or absorbing excess power to ensure stable grid operation.
Promotes New Energy Integration: With the rapid development of new energy sources like PV and wind, integration challenges are becoming increasingly prominent. Grid-tied PV energy storage systems can enhance the grid’s capacity to integrate and absorb new energy, alleviating peak-shaving pressure. Through the dispatch of energy storage devices, the output of new energy power can be smoothed.
4. Microgrid Energy Storage System Application Scenario
As an important energy reserve device, microgrid energy storage systems play an increasingly vital role in China’s new energy development and power system. With technological advancements and the proliferation of renewable energy, the application scenarios for microgrid energy storage systems continue to expand, primarily including the following two aspects:
Distributed Generation and Storage Systems: Distributed generation involves establishing small-scale power generation equipment near the user side, such as solar PV or wind power. Excess generated electricity is stored via the energy storage system to provide power during peak demand periods or grid failures.
Microgrid Backup Power: In remote areas, islands, and other locations where grid access is difficult, microgrid energy storage systems can serve as backup power sources, providing stable electricity supply locally.
Microgrids, through multi-energy complementation, can fully and effectively leverage the potential of distributed clean energy, mitigating disadvantages such as small capacity, unstable generation power, and low reliability of independent power supply. They ensure the safe operation of the power grid, serving as a valuable supplement to the main grid. Microgrid application scenarios are more flexible, ranging in scale from several kilowatts to tens of megawatts, with a broader application scope.