Why do photovoltaic off-grid systems need to be equipped with energy storage iron phosphate lithium ion batteries?

In photovoltaic off-grid systems, lithium-ion batteries storing iron phosphate account for a large proportion. Their cost is similar to that of solar modules, but their life is much shorter than that of solar modules. The task of lithium-ion batteries storing iron is to store energy, ensure the stability of system power, and ensure the load power at night or in cloudy and rainy days.

1. Photovoltaic power generation time and load power consumption time are not necessarily synchronized, photovoltaic off-grid system, input is a component, used for power generation, output is connected to the load. Photovoltaic power generation is in the daytime, there is sunlight to generate electricity, often at noon, the highest power generation, but at noon, the demand for electricity is not high, many households use off-grid power station electricity at night, then how to do during the day, the energy storage device is to store iron phosphate lithium ion battery. Wait until peak demand, like 7 or 8 p.m., to release the power.

2. photovoltaic power and load power is not necessarily the same, photovoltaic power is affected by radiation, is not very stable, and the load is not stable, like air conditioning, refrigerator, starting power is very large, usually less running power, if photovoltaic straight load, it will cause system instability, voltage rise and fall. The energy storage battery is a power balancing device. When the photovoltaic power is greater than the load power, the controller sends the excess energy to the battery pack for storage. When the photovoltaic power cannot meet the load requirements, the controller sends the electric energy of the battery to the load.

3. High cost of off-grid system. The off-grid system consists of photovoltaic array, solar controller, inverter, battery pack, load and so on. Compared with grid-connected systems, there are more batteries, which account for 30-40% of the cost of generating a system, almost as much as components. And the battery life is not long, lead-acid batteries are generally in 3-5 years, lithium ion batteries are generally in 8-10 years.