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SMA Battery Inverter: A Comprehensive Overview
What does a battery inverter do? And what is a battery inverter used for? A battery inverter, also known as a DC to AC inverter, converts the direct current (DC) stored in a battery into alternating current (AC), which is the type of current typically used in homes, businesses and industry. Battery inverters are therefore essential for making use of stored solar power. Here you can learn more about SMA battery inverters and how they can help you.
SMA battery inverters
Battery inverter for high-voltage batteries
Battery inverters for on- and off-grid applications
Battery Inverters for large scale storage solutions
Accessories
What is a battery inverter?
Battery inverters, converting 12V DC to 230V AC, play an important role in the operation of a PV system: PV systems generate direct current (DC) which must be converted into alternating current (AC) for use in homes, businesses, industry, and for feeding into the utility grid. This is the job of PV inverters. The same conversion process is also required to get electric current out of energy storage because the energy is stored in a battery in the form of direct current. The battery inverter converts this energy back into alternating current.
A battery storage system for PV systems generally consists of the following components:
A PV inverter for converting direct current (DC) into alternating current (AC)
A battery system, which incorporates a charge controller, for temporary storage of the generated energy
A DC/DC converter for controlling the voltage level
An off-grid battery inverter for converting the stored direct current into alternating current
Optionally, meter infrastructure to record the amount of power fed into the utility grid
It is important that the electricity-storage system is configured such that all operating modes of use for the home or business are possible. With appropriate planning, the following usage scenarios can be covered with a PV system and a battery inverter:
Direct feed-in of the solar power produced to the utility grid (without intermediate storage)
Direct use of the energy produced within the home or business
Storage of surplus solar power in the battery storage system
Withdrawal of energy for self-consumption from the battery storage system
Feed-in of the battery current into the utility grid
The PV inverter converts direct current into alternating current
Alternating current is supplied to consumers
Direct current is generated by PV modules
Alternating current is fed into or drawn from the utility grid
Surplus electric current is stored
Battery inverter converts alternating current from the battery storage system into direct current
Difference from the hybrid inverter
A hybrid inverter can handle the tasks of both a standard PV inverter and those of a battery inverter. It therefore combines both functions in just one device. It can convert the direct current (DC) from the PV modules and the battery storage system into usable alternating current (AC) and put any surplus solar power into temporary storage in the battery storage system.
The advantages of a battery inverter – home and commercial systems
A residential battery inverter for SMA photovoltaic storage systems impresses users in many different ways.
The benefits at a glance
SMA supplies battery inverters for every conceivable application – be it for capping peak load, off-grid applications or ensuring grid stability.
SMA battery inverters are compatible with various battery technologies and batteries from various manufacturers and are therefore highly flexible.
SMA battery inverters can be integrated in existing PV systems and combined with E-charging stations or heat pumps at any time to make optimum use of the solar energy generated.
How exactly does a battery inverter work?
A battery inverter is essential in order to use the energy put into temporary storage in the battery or to feed energy into the utility grid because the energy in the battery exists in the form of direct current (DC). Yet, the utility grid and most consumers (electrical appliances, electrical machines) use alternating current (AC).
The battery inverter converts the direct current from the battery into alternating current.
This can then be fed into the home, business or utility grid.
In the process, the battery inverter keeps the output voltage and frequency stable at all times, which prevents fluctuations and therefore damage to consumers.
Due to the energy transition, grid stability faces a huge challenge because decentralised power generation from renewable energy sources is harder to control in terms of infrastructure utilisation. Battery inverters like those from SMA are therefore key to the success of the energy transition.
Secure power supply function
SMA battery inverters with a secure power supply function or battery-backup function supply a home, business or certain consumers with the energy stored even if the utility grid is down. More information is available in the planning guidelines SMA Home Energy Solution with battery-backup function.
Retrofitting batteries and battery inverters
When photovoltaics first came onto the scene, there were no batteries suitable for self-generated electric current. The first batteries were unappealing to most households because of their high original costs and huge size. Thanks to modern lithium-ion technology, things have changed. These days, storage solutions for PV systems with a lithium-ion battery inverter (also called "lithium battery inverter") or with a grid-tie battery inverter are comparatively compact and also cheap to buy and use.
Should you want to retrofit an existing PV system with a battery storage system, you can choose from the following options:
You can keep your existing PV inverter, which converts the PV system's direct current (DC) into alternating current (AC) for use in the home and for grid feed-in and retrofit the battery storage system adding a battery inverter.
You can add a hybrid inverter to the PV system. This combines the function of a PV inverter with that of a battery inverter in one device.
Frequently asked questions about battery inverters
Single-phase or three-phase battery inverter for home use?
A single-phase battery inverter is only suited to small PV systems in single-family homes. This variant is only permitted for PV systems of up to 4.6 kilovolt-amperes (kVA). Three-phase battery inverters are mandatory for larger systems in excess of 4.6 kVA. If you want to use an inverter with a battery to feed power into the utility grid or with a secure power supply function, then an SMA three-phase battery inverter is ideal. This setup will ensure that the energy is fed constantly into the utility grid and by providing a secure power supply to the home or business, all consumers can be reliably powered.
Which battery is best for an inverter of 1000 / 2000 / 3000 watts?
It's not easy to provide a blanket response to this question but as a rule: the larger the PV system, the more powerful the inverter and linked battery should be. For a high-capacity setup a battery inverter 3000W might be needed. The SMA Home Storage can be configured to power output of 3.2 kWh to 16.4 kWh and is the right solution for all three variants.
Why can't you use a battery inverter in a system without a PV inverter?
The PV inverter and battery inverter in a PV system work together. This ensures that efficient use is made of solar energy, the batteries are charged and the energy requirements of the building and utility grid are met.
The PV inverter converts direct current into alternating current, feeds surplus energy into the utility grid and ensures energy optimisation. And all this happens without a battery inverter.
However, a battery inverter alone can only convert direct current from a battery into the alternating current needed – so it is only fully functional when combined with a PV inverter.
How do you select the right battery inverter?
There are various factors which influence which battery inverter is suitable for a PV system: these include the size and rating of the PV system and the capacity of the battery. But it isn't just compatibility that matters, there are other features that come into play too. Additional functions, such as integrated energy management, should also be taken into account as should the highest energy output possible. Our trained PV professionals and the SMA Sunny Design planning tool will assist with planning.
How far away from the battery can the inverter be?
Most battery storage system manufacturers permit cable lengths of no more than 5 to 10 metres between the storage unit and battery inverter. All battery manufacturers state their precise requirements in their product documents. As well as the cable length, also note the cross-section. If the cable route passes through outdoor areas, you will also need UV-resistant insulation. As a rule: both a battery and the PV inverter and battery inverter combination will produce heat during operation. The maximum ambient temperature stated in the product documents must therefore be observed. So while the components should be located as close together as possible, the spacing between them should be sufficient to allow the heat to dissipate.