With the acceleration of the global energy transition, 'photovoltaic + energy storage' has become a highly promising green energy solution. This system, by integrating solar power generation with energy storage devices, not only enhances energy utilization efficiency but also effectively resolves the intermittency and instability issues of photovoltaic power generation. The integration of photovoltaic and energy storage has become a standard feature for an increasing number of photovoltaic developments. The combination of energy storage will bring long-term and sustainable development momentum to photovoltaic power.

First of all, the core components of a photovoltaic system are solar panels and inverters. Inverters can convert solar panels into alternating current for daily use, providing clean electricity for households, businesses or power grids. However, due to the discontinuity of sunlight, photovoltaic power generation cannot operate normally at night or in rainy and cloudy weather. To solve this problem, energy storage batteries are key. So how to integrate photovoltaic and energy storage? Below, we will introduce several solutions respectively based on different application scenarios and capacity requirements.

Photovoltaic grid-connected energy storage system solution

Photovoltaic energy storage integration method: DC coupling

Working logic: When the solar power is greater than the load power, part of the solar power is converted into alternating current through the inverter to supply power to the load, and the remaining inverter will store the electrical energy in the battery. When the solar power cannot meet the load requirements, the inverter converts the electrical energy stored in the battery to supply the load, ensuring the continuity and stability of the entire system's operation.

Application scenarios: It is applied in scenarios where the surplus of photovoltaic power generation and self-consumption cannot be fed to the grid, the self-consumption electricity price is higher than the feed-in electricity price, and the peak electricity price is more expensive than the flat electricity price.

Advantage: During the day when the sunlight is strong and the electricity consumption is not high, it stores the excess electricity generated to increase the proportion of self-generated and self-consumed electricity.

Photovoltaic energy storage integration method: DC coupling

Working logic: When the solar power is greater than the load power, part of the solar power is converted into alternating current through the inverter to supply power to the load, and the remaining inverter will store the electrical energy in the battery. When the solar power cannot meet the load requirements, the inverter converts the electrical energy stored in the battery to supply the load, ensuring the continuity and stability of the entire system's operation.

Application scenarios: It is applied in scenarios where the surplus of photovoltaic power generation and self-consumption cannot be fed to the grid, the self-consumption electricity price is higher than the feed-in electricity price, and the peak electricity price is more expensive than the flat electricity price. Advantage: During the day when the sunlight is strong and the electricity consumption is not high, it stores the excess electricity generated to increase the proportion of self-generated and self-consumed electricity.

Photovoltaic grid-connected and off-grid energy storage system solutions

Working logic: 

Under the condition of sunlight, the photovoltaic array converts solar energy into electrical energy, which is then supplied to the load through the integrated machine and charges the battery pack at the same time. When there is no sunlight, the battery supplies power to the solar control inverter integrated machine and then to the AC load. When the power grid is out of power, it switches to off-grid mode and supplies power to important loads through backup power mode. When the power grid is restored, it switches back to grid-connected operation.

Application scenarios: 

Mainly applicable to situations where the power grid is unstable and has significant loads, or where self-generated and self-consumed photovoltaic power cannot be fed to the grid with surplus power, where the self-consumption price is much higher than the feed-in price, and where the peak price is much higher than the off-peak price, etc.

Advantages:

It can utilize the battery to store the electricity converted by the photovoltaic array, increasing the proportion of self-generated and self-consumed electricity. It can also charge the battery during off-peak hours and use it during peak hours to reduce electricity bills. Most importantly, when the power grid is out of power, it can switch to off-grid operation and be used as a backup power source.

Photovoltaic off-grid energy storage system solutions

Working logic:

It operates independently without relying on the power grid, converting direct current into household alternating current under sunlight conditions to supply power to the load and charge the battery pack at the same time. When there is no light, the AC load is powered by the battery through the inverter.

Application scenarios:

Widely used in remote mountainous areas, areas without electricity, islands, communication base stations and street lamps, etc. It is mainly used in areas without power grids or areas with frequent power outages.

Advantages:

It is not restricted by geographical location, does not rely on the power grid, has a wide range of applications, and can be installed and used as long as there is sunlight.

Photovoltaic microgrid energy storage system solution

Working logic: 

It can operate either in parallel with the external power grid or in isolation. The photovoltaic array converts solar energy into electrical energy under the condition of sunlight, supplies power to the load through the inverter, and charges the battery pack at the same time through the PCS energy storage converter. When there is no light, the battery supplies power to the load through the PCS energy storage converter.

Application scenarios: 

It is suitable for places with a large number of people living on islands and in remote mountainous areas to establish small and medium-sized distributed power sources

Advantages:

It encompasses all applications of both off-grid and grid-connected systems, features multiple working modes, maximizes the utilization of photovoltaic power, and reduces the user's reliance on the power grid. The microgrid system can fully and effectively tap the potential of distributed clean energy, reduce unfavorable factors such as unstable power generation and low reliability of independent power supply, ensure the safe operation of the power grid, promote the upgrading and transformation of traditional industries, and play a huge role from the perspective of economy and environmental protection.

The 'photovoltaic + energy storage' integrated solution achieves efficient energy utilization and stable output by diversifying the organic combination of photovoltaic power generation systems and energy storage systems. In addition to technological innovations, active explorations have also been made in business models. By introducing energy storage facilities, photovoltaic power generation projects can achieve various value-added services such as peak-valley electricity price arbitrage and demand-side response, thereby enhancing the economic viability of the projects. Meanwhile, energy storage systems can also serve as an important component of virtual power plants (VPPS), participating in auxiliary services such as frequency regulation and peak shaving for the power grid, further enhancing the market competitiveness of photovoltaic power generation.

In the future, with the continuous advancement of energy storage technology and the further reduction of costs, the 'photovoltaic + energy storage' integrated solution will become more widespread, providing strong support for the green and low-carbon transformation of global energy. The government, enterprises and all sectors of society should make joint efforts to promote the research and application of relevant technologies and accelerate the construction of a clean, safe and efficient energy system.