Utilizing a single inverter to power the load, thereby saving costs

Fewer components, lower costs, and reduced maintenance requirements

Higher efficiency due to the lack of multiple inverters of electrical energy (less energy loss)

The cable between BESS and PV is shorter, which helps to reduce losses

Not suitable for modification (requires replacing existing inverters; in many cases, reconfiguring photovoltaic array wiring; complex installation based on existing photovoltaic systems)

Comparison of technical routes for parallel and offline systems

There are many technical routes for parallel off grid optical storage systems, including solar modules, controllers, inverters, batteries, loads, and other equipment. According to the method of energy aggregation, there are currently two main topologies: DC coupling and AC coupling.

01 DC coupling

The direct current generated by photovoltaic modules is stored in the battery pack through the controller, and the power grid can also charge the battery through a bidirectional DC-AC converter. The convergence point of energy is at the DC battery end

The working principle of DC coupling: When the photovoltaic system is running, the MPPT controller is used to charge the battery; When there is a demand for electrical load, the battery will release electricity, and the magnitude of the current is determined by the load. The energy storage system is connected to the power grid, and if the load is small and the battery is fully charged, the photovoltaic system can supply power to the grid. When the load power is greater than the photovoltaic power generation power, the power grid and photovoltaic can simultaneously supply power to the load. Because photovoltaic power generation and load electricity consumption are not stable, they rely on battery balancing system energy.

02 AC coupling

The direct current generated by photovoltaic modules is converted into alternating current through an inverter, which is directly fed to the load or sent to the power grid. The power grid can also charge the battery through a bidirectional DC-AC bidirectional converter. The convergence point of energy is at the communication end.

The working principle of AC coupling: including photovoltaic power supply system and battery power supply system. The photovoltaic system consists of a photovoltaic array and a grid connected inverter; The battery system consists of a battery pack and a bidirectional inverter. These two systems can operate independently without interfering with each other, or they can form a microgrid system independent of the large power grid.