What are the different batteries for solar panel inverters.
Solar panels only generate electricity when sunlight is available, so to ensure uninterrupted power supply it is important to use batteries that store energy for later use. There are several basic types of batteries suitable for solar panel inverters:
- Lead-acid batteries (AGM and GEL):
- These are traditional batteries that are widely used because of their availability and low cost.
- AGM (Absorbent Glass Mat) is highly resistant to discharges and easy to use, while GEL (gel batteries) are resistant to deep discharges and have a long service life.
- Disadvantages: heavy weight, limited life cycle (300-800 cycles), need for regular maintenance (in the case of classic lead-acid models).
- Lithium-ion batteries (Li-ion):
- Lightweight, compact and have high energy density.
- They are characterised by a long service life (up to 5000 cycles) and deep discharge capability (up to 80-90%).
- Disadvantages: high cost and the need for overheating protection.
- Lithium-iron-phosphate batteries (LiFePO4):
- It is a subspecies of lithium-ion batteries with improved safety and durability characteristics.
- High resistance to overheating and mechanical damage, service life up to 10-15 years, high number of cycles (up to 7000).
- Disadvantages: high initial cost.
- Nickel-cadmium (Ni-Cd) and nickel-metal hydride (NiMH) batteries:
- Resistant to extreme temperatures and can withstand deep discharges.
- Used less frequently due to lower efficiency and environmental constraints.
Why are lithium-iron-phosphate batteries considered the best?
Lithium iron phosphate batteries (LiFePO4) are considered the best choice for solar panel inverters due to the following reasons:
- Long service life:
- They can withstand up to 7000 charge-discharge cycles, which is 5-10 times more than lead-acid batteries.
- Deep discharge:
- LiFePO4 allows deep discharges (up to 80-90%) without significant impact on the service life, which maximises the use of stored energy.
- High security:
- These batteries are resistant to overheating, short circuits and mechanical damage, making them reliable even in difficult conditions.
- Eco-friendliness:
- Lithium-iron-phosphate batteries are more environmentally friendly because they do not contain toxic materials such as lead or cadmium.
- Efficiency:
- They have high energy density and low self-discharge, making them efficient for long-term storage.
- Compact and lightweight:
- These batteries are more compact and lightweight than their counterparts, which is important when space is limited.
Calculation of the required battery capacity.
For proper battery selection, it is important to calculate the required capacity based on the total energy consumption. Basic calculation steps:
- Determine the daily energy consumption:
- Add up the power of all appliances that will be powered by the system and multiply it by their run time in hours.
- Take into account the efficiency of the inverter:
- Inverters have an efficiency (typically 90-95%), so divide the calculated value by this factor.
- Calculate the required battery capacity:
- Divide the daily consumption by the battery voltage (e.g. 48V).
- Add a reserve of capacity:
- It is recommended to select a battery with a 10-20% reserve to increase battery life and compensate for possible peak loads.
Example: if the total daily consumption is 5000Wh and a 48V battery is used, the capacity calculation would be as follows:
5000 Wh / 48 V = 104.2 Ah. With a 20% reserve: 104.2 × 1.2 = 125 Ah.
Recommendations for battery selection.
It is important to remember not to buy batteries from dodgy sellers, as a battery is a high-risk piece of equipment. Saving money at the expense of safety may result in damage to the facility or endanger life. Only purchase batteries from trusted suppliers and ensure that quality certificates are available.
In our projects we use LiFePO4 batteries from the British company SunSynk. The equipment of this company impresses with its quality and reliability.
Battery installation location.
Choosing the right place to mount your battery is critical to its performance and longevity:
- Installation next to the inverter:
- Typically, batteries are installed with the inverter to avoid the need to run long power cables that increase power loss and cost.
- Premises for installation:
- Batteries and inverters can be located on outside terraces or in utility rooms. If the space is enclosed, ventilation should be provided as the power equipment gets very hot when operating under load.
- Outdoor installation:
- When installing outdoors, it is important to consider the climatic conditions of the area to avoid the following risks:
- Frost, which can affect the operation of the equipment.
- Sea breeze with high salinity that can cause corrosion.
- Direct solar radiation that leads to overheating.
- Flooding or heavy rains with high humidity (up to 100%).
- When installing outdoors, it is important to consider the climatic conditions of the area to avoid the following risks:
Many factors, including temperature, humidity and environmental influences, affect the performance, durability and safety of power equipment. Therefore, the choice of installation location must be carefully considered.
Conclusion.
When selecting a battery for solar panels, it is important to consider factors such as budget, durability requirements, safety and available space. Despite the high initial cost, lithium-iron-phosphate batteries provide the best combination of features, making them the optimal solution for solar energy systems.
