The battery for a solar system is essential for storing the energy generated by the photovoltaic s, guaranteeing electricity even when the sun is not available.
With different technologies and applications, they can be used in off-grid systems, ensuring independence from the electrical grid, or in hybrid systems, providing backup in case of blackouts.
But how do you choose the best battery? How long does it last? And how much does it cost to invest in a storage system? In this article, you will find everything you need to know about Batteries and how they can transform the use of renewable energy in your home or business.
What is battery for solar system?
Batteries are used in photovoltaic systems to store energy. They can supply electricity to s at times when there is not enough solar energy generated in off-grid systems, such as on cloudy days and at night.
In hybrid systems, batteries act as a backup, ensuring power supply in the event of blackouts. In this way, they function as a UPS, preventing the interruption of electrical equipment during power outages, with almost instantaneous and imperceptible transfer.
A hybrid system is any configuration that combines two or more energy sources, such as a diesel generator and solar, wind and solar, or solar with batteries, ensuring greater efficiency and flexibility in the electrical supply.
Batteries may or may not have a backup function. Those that do have this function are usually more expensive because they need to be grid-forming.
Most of them are currently grid followers, which are used more for applications to reduce contracted demand or shift consumption times or inject into the grid. In the latter, the aim is to buy energy (use the grid) at times when tariffs are cheaper and sell energy (inject) at times when they pay more.
With the use of solar batteries, it is possible to significantly increase energy autonomy, reducing dependence on the electricity grid and even disconnecting completely, eliminating concerns about power cuts.
Additionally, there are network-connected applications such as time shift e peak-shaving, which seek, respectively, to use the energy stored in the batteries during times of high tariffs and to avoid exceeding demand.
What are the types of batteries for solar systems?
Choosing the ideal battery for a photovoltaic system depends on several factors, such as efficiency, useful life, cost and application. There are different technologies on the market, each with specific characteristics that better meet certain needs.
From traditional lead-acid batteries, known for their robustness and affordable cost, to advanced lithium-ion batteries, which stand out for their high efficiency, safety and low maintenance, each option presents advantages and challenges.
In addition, there are also flow and nickel-sodium batteries, innovative solutions aimed at larger applications. Below, learn about the main technologies available and their characteristics.
Chumbo acido
The oldest solar system battery on the market. It first appeared at the beginning of the last century, in the 1900s. Its main advantages include resistance to high temperatures (up to 60 ºC), ability to withstand occasional deep discharges, ease of recycling and robust construction, dispensing with specialized maintenance or complex electronic monitoring and control systems;
Lithium ions
They are currently the big stars of the storage market, with many applications in energy systems and electric mobility. Lithium batteries stand out for their long service life, high energy density and reduced weight compared to lead-acid batteries.
In addition to being environmentally friendly, they must have a management system (BMS) due to safety issues, since, if they are outside of ideal operating conditions, they can enter Thermal Runaway, when they burn non-stop until the lithium runs out.
Therefore, the BMS plays the role of temperature management, removing the hottest cells from operation until normalization occurs. Larger and more robust systems have their own cooling system, which is done by a liquid that es through the cells, cooling them and is also controlled by the BMS.
Solar flow battery
They are a little different from other electrochemical batteries that we know. This type of battery is viable in large-scale storage systems and is very advantageous due to its high longevity (with more than 10.000 charge and discharge cycles).
Its specific energy (Wh/kg) is similar to that of lead-acid batteries. This fact, associated with its construction complexity and low response speed, makes its use in mobile systems unfeasible.
Nickel sodium
This type of battery uses electrodes composed of salt in a liquid state. For this to be possible, it is necessary to keep the salt heated to high temperatures (around 350 ºC) through an internal heating system.
This is not very practical for mobile applications, but for stationary power systems, the technology is viable and promising. It has the advantage of being highly durable, and can be stored for many years at room temperature, when its electrodes acquire a solid state.
What is the best battery for a solar system?
The best battery for a solar system depends on the specific needs of the project, such as cost, efficiency, durability, and application. Currently, lithium-ion batteries are the most recommended for photovoltaic systems due to their high efficiency, long service life, and low maintenance.
Lithium-ion technology has enabled the advancement of the use of energy storage systems, mainly associated with intermittent renewable sources (solar and wind), and is also responsible for the popularization of electric vehicles.
What are the types of solar systems with battery backup? And how do they work?
Photovoltaic systems can operate in different ways, depending on the consumer's needs and the available infrastructure. Among the main backup options are off-grid and hybrid systems, which guarantee the supply of energy in places without access to the electricity grid or in situations of instability.
While off-grid works autonomously, storing energy in batteries for continuous use, hybrid systems combine connection to the grid with storage, offering greater energy security and optimized consumption.
See below the details of each application:
Off grid
The off-grid system is not connected to the electrical grid, so it is recommended for isolated communities or rural areas, places where there are generally no power transmission lines. Excess energy can be stored in batteries, to be used during periods of low solar radiation and at night.
The fundamental equipment for this type of system, in addition to the batteries, are: photovoltaic modules, inverters to control the charging/discharging of the batteries and inverters to convert direct current into alternating current.
Hybrid
The hybrid system is connected to the power grid and also has the functionality of storing energy in batteries. This ensures the continuity of the supply of electricity to the consumer's essential equipment.
For example, when the grid is available, the system will operate normally as an on-grid system, supplying power to loads and injecting excess power into the grid. If the grid stops transmitting power, the system will be able to supply backup loads with the energy stored in the batteries.
How long does a solar battery last?
Over time, it may be necessary to replace the solar system battery, as its useful life varies between 5 and 15 years, depending on factors such as temperature, voltage and discharge rate.
Effective battery management includes planning for replacement when battery capacity begins to significantly reduce. Lead-acid batteries tend to have a shorter lifespan and require more frequent replacement, while lithium-ion batteries offer greater longevity.
In addition to replacement, it is essential to ensure proper disposal or recycling, following environmental regulations, as batteries contain materials that can be harmful to the environment if not handled correctly.
How many solar batteries are needed for a house?
To figure out how many solar batteries you will need to power a home, you must accurately calculate the total energy consumption. This calculation is made by multiplying the power of the equipment (in kW) by the time of use (in hours), providing an accurate measure of the energy consumed.
For example, a 3 kW appliance used for 4 hours would consume 12 kWh (3 kW x 4 hours = 12 kWh). However, depending on the size of the property and the number of appliances installed, looking for technical data labels, analyzing the power of each one and interpreting them can be laborious.
How much does a battery for solar energy cost?
The battery for a solar system is generally the most expensive component, and can for more than 50% of the total cost. Its price varies according to the technology used, as each type of battery has advantages and disadvantages, being more suitable for different applications.
In addition to technology, factors such as manufacturer, capacity and technical specifications also influence the final price. The cost of solar system batteries fluctuates due to the price of raw materials, most of which are imported or quoted in dollars. Even when produced in Brazil, many of their inputs are commodities with prices linked to the international market.
Average values can vary between R$500,00 to R$2.000,00 per kWh for lead-acid batteries and between R$2.500,00 to R$5.000,00 per kWh for lithium batteries.
According to research by Greener, by 2025, the forecast is that lithium battery price fall another 22% and reach the range of US$ 90,00/kWh. By 2030, the expectation is that the price will continue to fall and reach US$ 64,00/kWh.
After all, is it worth installing a battery for residential solar energy?
Investing in batteries for your solar system guarantees greater autonomy, safety and savings. With them, you can use solar energy at night, on cloudy days or during blackouts, reducing your dependence on the electricity grid. In addition, it allows you to save on your electricity bill, taking advantage of the stored energy during peak hours.
As technology advances and prices become more affordable, investment becomes increasingly advantageous. For those seeking energy independence, predictable spending and a more sustainable future, the answer is clear: it is well worth it.
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Conclusion
There is no doubt that technological evolution has made batteries for solar systems more durable, efficient and accessible, expanding their advantages for residential and commercial consumers.
Given the growing search for sustainable solutions and energy independence, investing in solar batteries is worthwhile and can make a big difference for the future of energy consumption.
