Application of Hybrid and off grid energy storage inverter in photovoltaic energy storage system

Foreword: In recent years, with the decline of photovoltaic subsidies in various countries, the investment income of pure photovoltaic projects has declined, and photovoltaic energy storage system has become the choice of more and more people.
According to different applications, photovoltaic energy storage power generation system can be divided into four categories.

Off grid energy storage system.

Off grid power generation system

Grid connected energy storage system

Multi energy hybrid microgrid system

Parallel off-grid energy storage system is widely used in photovoltaic spontaneous self-use can not spare the grid, self-use price is much more expensive than the grid price, peak price is much more expensive than the trough price and other applications.

The PV parallel off-grid energy storage system is composed of PV array, Hybrid parallel off-grid energy storage inverter, battery pack, load, grid and so on. Photovoltaic array converts solar energy into electricity in the case of illumination, and charges the battery group by supplying power to the load through parallel and off-grid energy storage inverter; in the absence of illumination, the battery and the grid supply power to the AC load.

Compared with grid-connected generation system, the cost of off-grid integrated system is increased, but the application scope is wider and the function is more powerful.

The core part of the system is the Hybrid parallel off-grid energy storage inverter. By setting the inverter, a variety of working modes can be achieved. In this paper, the working mode of parallel-off-grid energy storage inverter is introduced, and a typical parallel-off-grid energy storage system is configured.

And the working mode of off grid energy storage inverters:

1. Self utilization mode: suitable for low subsidies and high electricity prices.

During the day when the sun is shining, the energy from the panels is supplied to the load first, and the excess energy is supplied to the battery to charge and then sold to the grid.
Priority: load > battery > Power Grid

1. battery power generation

2. load consumption

3. excess energy is stored in batteries.

4. the remaining energy is sold to the grid.

When the battery panel does not generate electricity at night, the battery first discharges to the load for use, and when the battery is used up, the grid supplies power to the load.

1. battery discharge

2. power supply to power grid

3. load consumption

2. Time mode: It is suitable for areas with large gap between peak and valley price. By setting the charging and discharging period of batteries manually, the peak and valley can be cut and filled, and the price difference between peak and valley can be earned. The higher the difference is, the higher the corresponding income will be.

When the electricity price is cheap, the load will be used by the power grid and the electricity stored on the battery board will be stored.

Priority: Battery > Load > Power Grid

When the electricity price is high, the battery will be used first.

Priority: load > battery > Power Grid

1. battery power generation

2. store energy in batteries.

3. load consumption

4. power supply to power grid