What type of battery is used in the solar cell power supply scheme.
The solar power supply scheme mainly consists of solar lithium batteries and panels, crystalline silicon wafers, and an overall performance monitoring system. Collecting the energy of the sun from solar panels and outputting it through a voltage regulator, many products now use solar cells, such as solar street lights and solar water heaters. Most houses now use solar cells for power supply, often to avoid high energy costs.
Once the power grid fails, there are many types of solar cells that can be used as backup power sources. Installing a high-power instant backup power source like UPS allows us to choose different types of solar cells to drive your solar system.
1、 What is a solar cell?
Solar cells are devices that use solar energy to generate electricity. Simply put, a solar cell is a semiconductor photodiode. When sunlight shines on the photodiode, it converts solar energy into electrical energy, generates current, and stores the energy in your energy system. The storage capacity of different types of solar cells corresponds to their capacity, and solar cells store electrical energy for future use. When your battery is fully charged, the BMS system will automatically turn off charging. When the battery is used and its power is depleted, the BMS system will intelligently identify that the lithium battery pack capacity is insufficient, intelligently start the lithium battery pack to continue charging, and absorb power from the panel again.
2、 Can solar panels charge lithium batteries?
Sure, regarding the issue of solar panels being able to directly charge lithium batteries, charging the lithium battery pack directly is not feasible because the voltage of the solar panel is unstable and cannot directly charge the lithium battery. A voltage regulator circuit is required, and a corresponding lithium battery charging circuit is also needed to charge the battery. The charging requirements for lithium batteries are quite strict and cannot be overcharged. If overcharged, there may be a situation where a battery cell deforms, explodes, or catches fire.
3、 Different types of solar cells
1. Lithium iron phosphate battery
The lithium iron phosphate battery energy storage system consists of a lithium iron phosphate battery pack, a Battery Management System (BMS), a converter device (rectifier, inverter), a central monitoring system, transformers, etc. Lithium iron phosphate batteries have a series of unique advantages such as high working voltage, high energy density, long cycle life, low self discharge rate, no memory effect, and green environmental protection. They also support stepless expansion and are suitable for large-scale energy storage. They have good application prospects in the fields of safe grid connection in renewable energy power plants, grid peak regulation, distributed power plants, UPS power supply, emergency power systems, etc.
2. Ternary lithium battery
Ternary lithium batteries have a working voltage range of 2.5V-4.2V and a nominal voltage of 3.6V. Common models such as BYD and Tesla use this type of battery, which is much smaller in size and lighter in weight compared to regular batteries. Generally, lithium-ion batteries of the same model are only half the size of batteries and weigh one-third of batteries. Compared to ordinary batteries, ternary lithium-ion batteries are greener and have less environmental pollution because their long service life can prevent environmental pollution caused by replacing ordinary batteries.
4、 What are the factors to consider when building solar cells?
1. Capacity
Capacity represents the ability of solar cells to store electrical energy. Lithium batteries have a larger capacity than other batteries, higher energy density, and longer battery life.
2. Voltage
Different types of batteries have different voltage ranges. The nominal voltage of lithium iron phosphate is 3.2V, and the nominal voltage of ternary lithium batteries is 3.6V. When assembling a battery pack, after understanding the voltage of the battery pack, choose to connect the batteries in series to achieve the required voltage value.
3. charge and discharge current
Firstly, it is necessary to understand the maximum charging and discharging current of the battery cell. The charging current of the solar cell group cannot be higher than the continuous charging current of the battery cell. It can be lower than this value, but it will affect the charging efficiency. The discharge current is determined based on the actual discharge current, and the battery cells and parallel connected batteries are used to meet the required discharge current value.
4. Discharge depth:
The cycle life of lithium iron phosphate batteries is around 2000-3000 times, and after assembly into a PACK battery pack, the cycle life is around 1500-2000 times; The cycle life of ternary lithium batteries is around 500-800 times, and after assembly into a PACK battery pack, the cycle life is around 300-500 times. (Test conditions: 1C charge and discharge, 25 ℃ laboratory environment, discharge depth DOD100%) Whether it is the battery cell or the battery pack PACK, the lifespan of lithium iron phosphate batteries will be much longer than that of ternary lithium batteries.
5. BMS management system
The BATTERY Management System is the link between batteries and users, mainly targeting secondary batteries and not related to disposable batteries. The main purpose of a Battery Management System (BMS) is to improve battery utilization, prevent overcharging and overdischarging, extend battery life, and monitor battery status.
6. Environmental temperature
Although lithium iron phosphate batteries are resistant to high temperatures, ternary lithium batteries have better low-temperature resistance and are the main technology route for manufacturing low-temperature lithium batteries. At minus 20 ° C, ternary lithium batteries can release 70.14% of their capacity, while lithium iron phosphate batteries can only release 54.94% of their capacity. Moreover, due to the low temperature conditions, the discharge platform of ternary lithium batteries is much higher than that of lithium iron phosphate batteries, and they start faster.
In the final solar cell power supply plan, we need to select suitable battery packs based on actual usage factors.
