The role of lithium batteries in solar off-grid systems

Why should the photovoltaic off-grid system be equipped with energy storage lithium iron phosphate battery? Energy storage batteries in the off-grid system is essential, solar panels through the controller to the storage battery charging, by the lithium iron battery through the off-grid inverter inverter output for the user to use, energy storage batteries in the photovoltaic off-grid system more commonly used is lithium iron phosphate batteries, lead-acid batteries and so on.

PV off-grid system composition

PV modules, off-grid inverters (including PV chargers/inverters), storage batteries (lead-acid/colloidal/lead-carbon/lithium ternary/lithium iron phosphate, etc.), PV mounts, cables, and distribution boxes are all important components of PV off-grid systems.

The biggest difference between off-grid PV systems and grid-connected systems is that grid-connected systems are calculated on the premise of return on investment, while off-grid systems are calculated on the premise of immediate need for power supply, so they will have a different focus in the selection of components.

 Why should PV off-grid system be equipped with lithium iron phosphate battery for energy storage?

In the photovoltaic off-grid system, li ion solar battery account for a large proportion of the cost and the solar module is almost the same, but the life expectancy is much shorter than the module, storage lithium iron batteries are tasked with storing energy to ensure that the system power is stable, and to ensure that the load is powered at night or on cloudy or rainy days.

First, photovoltaic power generation time and load power time is not necessarily synchronized, photovoltaic off-grid system, the input is the module for power generation, the output is connected to the load. Photovoltaic are daytime power generation, sunlight to generate electricity, often at noon power generation power is the highest, but at noon, electricity demand is not high, many household off-grid power station at night to use electricity, that daytime electricity how to do, to be the first to store energy up, this storage device is the storage of lithium iron phosphate batteries. Waiting for the peak of electricity consumption such as seven or eight o'clock at night, and then release the power.

Second, photovoltaic power and load power is not necessarily the same, photovoltaic power generation by the impact of radiation, not very stable, and the load is not stable, like air conditioning, refrigerators, start-up power is very large, usually run less power, if the photovoltaic directly with the load, it will cause the system is not stable, the voltage fluctuates high and low.

Energy storage battery is a power balancing device, when the PV power is greater than the load power, the controller sends the excess energy to the battery storage, when the PV power can not meet the needs of the load, the controller sends the battery power to the load.

Third, off-grid system cost and lithium battery cost is high. Off-grid system consists of photovoltaic arrays, solar controllers, inverters, battery packs, loads and other components. Compared with the grid-connected system, more batteries, occupying 30-40% of the cost of the power generation system, and components are almost the same. And the service life of the battery are not long, lead-acid batteries are generally 3-5 years, lithium batteries are generally 8-10 years, after the need to replace.

New energy storage lithium iron phosphate batteries, as a photovoltaic system of energy storage devices, energy storage efficiency can be increased to 95%, can significantly reduce the cost of solar power. Lithium batteries have 95% energy efficiency, while the current commonly used lead-acid batteries, only about 80%. Lithium batteries are lighter in weight and have a longer service life than lead-acid batteries. Charge and discharge times can reach 1600 cycles, which means they do not need to be replaced often.

At present, photovoltaic power generation energy storage more and more to take lithium batteries along with technological breakthroughs in updating, ternary lithium / lithium iron phosphate battery market share in the photovoltaic off-grid system gradually increased, which is a new application trend.

Summary: lithium battery energy storage in recent years in all types of energy storage systems in the new installed capacity of the proportion gradually increased, according to the status quo of domestic and foreign energy storage power station applications and battery characteristics, it is recommended that the battery selection of lithium ion battery companies is mainly lithium iron phosphate battery.