Inverters are very important in modern energy systems, especially in renewable energy systems.  The main function of the inverter is to convert the direct current generated by a DC power source such as a photovoltaic panel, fuel cell, or lithium battery to alternating current compatible with the grid and connect it to the grid.How to realize the current flow into the grid has become a problem that many people are concerned about in this process.The potential difference, potential difference, and the working principle of the inverter will be explained to answer this question better and to explore the grid-connected photovoltaic inverters, fuel cells, or lithium batteries, as well as the current limiting function of the inverter.
 

1. In which way does the grid-connected inverter achieve current flow to the grid?

The grid-connected inverter's essential role includes converting DC into AC and ensuring that the output AC can be fed smoothly into the grid.Voltage matching and frequency synchronization are the working principles of an inverter.The AC voltage generated by the inverter needs to be consistent in terms of amplitude, frequency, and phase with the grid voltage.If the inverter's AC output voltage is incompatible with the voltage at the grid, then it cannot smoothen the current flow into the grid and may even affect the stability of the latter.
 
The flow of current follows the basic principle of potential difference: only when there is a voltage difference between two points can the current flow from the place where the voltage is high to the place where the current is low.In other words, for grid-connected inverters, it means the output AC voltage of the inverter needs to keep a certain potential difference from the grid voltage.Specifically, when the output voltage of the inverter is higher than the grid voltage, the current will flow from the inverter into the grid;  When the grid voltage is higher than the output voltage of the inverter, the current will not flow into the grid, and the inverter needs to adjust its output voltage to ensure that the current can flow into the grid smoothly.
 
Moreover, it has to track the frequency and phase of the grid in real-time to ensure synchronization.The current of the grid and the current output of the inverter should keep the same frequency and phase, so that when the current flows into the grid, it would not cause any phase difference that results in grid fluctuations.  Therefore, the inverter ensures the output AC can flow steadily into the grid by regulating voltage, frequency, and phase.
 
2.Is potential or potential difference needed to create the flow of current into the grid?
Yes, the flow of electricity is essentially driven by a potential difference or potential difference.  Potential difference is the difference between two potentials, and the voltage difference means the voltage difference between two points.  In the application of a grid-connected inverter, the voltage difference between the inverter and the grid determines the direction of current flow.  Only when there is a certain potential difference between the output voltage of the inverter and the grid voltage, the current will flow to the grid.The inverter guarantees that this voltage difference is within the appropriate range by adjusting the output voltage to meet its purpose of allowing current flow to the grid.
 
3.Whether the photovoltaic grid-connected inverter can connect with the fuel cell or lithium battery assumed hereinbelow to realize the grid power generation:
Photovoltaic grid-connected inverters can be connected not only to a photovoltaic panel system but also to other types of DC power supplies, like fuel cells or lithium batteries, for grid-connected power generation.The basic working principle is the same: direct current is converted into alternating current compatible with the grid through an inverter.
 
The output characteristics of fuel cells and lithium batteries are similar to those of photovoltaic cells: both provide DC power, but their voltage and current output may be different.Normally, the output voltage of a fuel cell is seriously affected by the change of the load, and the voltage of a lithium battery may change with the charging state and the health state of the battery.  Therefore, when these energy systems are interfacing with the grid, an inverter requires sufficient flexibility in adjusting the voltage and current output so it can precisely match the voltage, frequency, and phase of the grid.
 
Generally speaking, photovoltaic grid-connected inverters can be connected to the grid with fuel cell and lithium battery systems, provided that the inverter can effectively convert direct current from different power sources into alternating current suitable for the grid and can cope with the challenges of fluctuations in battery or fuel cell output.
 
4.When grid-connected power generation is realized, can the inverter limit the current?
Current limiting is an important function of the grid-connected inverter, especially in the process of grid power generation.The inverter can monitor the current and voltage load of the grid and achieve current limiting by adjusting the output power.When the battery is highly charged or the power grid load is large, the inverter automatically adjusts the output to avoid too much current entering the power grid to prevent overload of the power grid load or damage to the device.
 
The limiting function of the current, provided in the inverter, controls it internally with an algorithm in such a way that the output current does not exceed the maximum allowed by the grid.For example, when voltage fluctuations or load changes occur within the grid, an inverter automatically reduces output power to avoid unnecessary current fluctuations and maintain grid stability.
 
In other words, the current limiting role of the inverter ensures that safety and stability are maintained in the power grid and prevents excessive power grid load or equipment damage that might be caused by the excessive output current of the inverter.

The grid-connected inverter works by adjusting the output voltage, frequency, and phase to guarantee it is synchronized with the grid voltage, hence enabling the flow of current into the grid.It does depend on the potential difference or voltage difference, and it is then that the current will flow smoothly into the grid;that is if an appropriate voltage difference exists between inverter output voltage and grid voltage.The photovoltaic grid-connected inverter can not only be connected to the grid with the photovoltaic panel but also DC power sources such as fuel cells and lithium batteries.Therefore, the inverter has to be adaptable enough to deal with fluctuations from different power sources.Finally, the current limiting function of the inverter can effectively prevent the grid load from being too large, and ensure the safety and stability of grid-connected power generation.