Solar batteries: function, benefits and products

Solar batteries (also known as ’solar storage systems’ or ’battery storage systems’) save solar energy and make it available for future use as and when needed. This means that the energy generated by the PV system can be used in the evening or at night when the sun is not shining or when current energy requirements exceed production. Solar batteries cut electricity costs, increase energy independence and reduce your carbon footprint.

Solar batteries: function, benefits and products

Solar batteries from SMA

SMA Home Storage

SMA Home Storage

Our power storage solution for the home - with around 8,000 battery cycles.

SMA Home Storage

How do solar batteries work?

Solar batteries save the energy generated by a PV system so that it can be used at some point in the future, for example in the evening or at night. Like car batteries, solar batteries save electrical energy in chemical form – and instantly convert it back to electrical energy as soon as it is needed. This process takes place in a ’battery cycle’. The solar batteries developed by SMA have around 8,000 battery cycles, for example, which is generally enough to last at least ten years before the battery capacity gradually diminishes.

Who can benefit from a solar battery?

Solar batteries are ideal for anyone looking to advance the energy transition. If you run or are planning a large-scale PV system and want to use as much solar power as possible for yourself, you should consider investing in a solar battery. This is because it makes currently unused PV-system-generated energy available for future use.

If you do not have the ability to store your self-generated solar power, you will be forced to either use it straight away or feed the surplus energy into the utility grid. And on cloudy days, in the evening or at night, so when the PV system is not producing any electricity, you will be forced to purchase energy from the utility grid. Purchased electricity generally costs more than the electricity fed into the grid. In addition, the feed-in tariff is likely to continue falling. So by retrofitting your PV system with a solar battery, you can start making immediate savings.

  • Direct current is generated by PV modules

  • Hybrid inverters convert direct current to alternating current

  • Alternating current is supplied to consumers

  • Alternating current is fed into or drawn from the utility grid

  • Surplus electric current is stored

Benefits of a solar battery

Solar batteries offer three key benefits: they increase your energy independence, optimise self-consumption and minimise your carbon footprint.

Optimise self-consumption

Optimise self-consumption

Drawing electricity from your solar battery during periods of high electricity demand or when your PV system is generating only small amounts of electricity means that you consume less of the expensive electricity from the utility grid and so, in turn, cut your costs.

Minimise your carbon footprint

Minimise your carbon footprint

Solar energy has a positive impact on your carbon footprint. A solar battery can help to further reduce the carbon footprint of homes and businesses because when the storage system is full, you do not need to purchase electricity from the utility grid – which is often obtained from fossil energy sources – during periods of low sunlight. 

Secure your energy independence

Secure your energy independence

If your PV system is not equipped with a solar battery, you will have to purchase electricity from external sources when your own system is generating only small amounts of electricity. A solar battery, however, allows you to reduce your dependency. When the storage system is full, you can still feed surplus power into the utility grid and receive payment for this. 

What makes a good solar battery?

A good solar battery offers high storage capacity, a long service life, high efficiency and effective energy management. Many solar batteries can be expanded and integrated seamlessly in your existing solar power infrastructure – including the flexible solar power storage solutions from SMA. A good solar battery should also be comparatively easy to install.

For homeowners and business owners

Ask for a consultation and find a specialist SMA solar power professional in your area.

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Good to know

Feed-in tariff

Feed-in tariff

The feed-in tariff depends on the energy source, size of your PV system, technology used, application area and time of commissioning. The defined feed-in tariffs can be found in the Renewable Energy Sources Act (EEG).

FAQs about solar batteries

What is a solar battery made of?

A solar battery usually comprises numerous battery cells. The lithium-ion cells are arranged in modules and installed inside an enclosure along with a cooling and safety system. Most solar batteries are equipped with an Accelerated Processing Unit (APU), which monitors the individual cells and ensures that they all charge and discharge evenly during the battery cycles. 

How safe are solar batteries?

When it comes to energy storage, safety is the top priority – and safety starts right at the manufacturing stage. Modern solar batteries in PV systems fulfil strict safety standards and come with numerous safety mechanisms. First, the energy management system permanently monitors operation; and second, multi-stage active and passive safety mechanisms prevent overcharge, overheating, deep discharging and short circuits. Solar batteries are so robust and solid that they are incapable of catching fire by themselves or even exploding. All these safety mechanisms are specially certified by external testing institutes.

Are there any drawbacks to battery storage systems?

Alongside the overwhelming advantages that battery storage systems provide, there are some minor drawbacks. First, there is the issue of space. If you want to upgrade or retrofit your PV system with a solar battery, you will have to make sure that enough space is available. That said, storage solutions are thankfully becoming ever more compact without any loss of battery capacity. 

Second, a battery storage system is of course an additional cost factor. The price depends on the size and storage capacity. This is why you should first review and calculate your self-consumption – for example using our solar power calculator. Businesses will need to think about overall cost-effectiveness – including original costs, saving potential and incentive options. The storage capacity should be aligned with a company’s energy requirements and capable of being expanded as and when required. 

Third, your carbon footprint. A solar battery will help you to reduce your carbon footprint only if it lasts as long as possible. Correct charging and discharging are critical here. 

What size of solar battery is best suited to my needs?

The size of the solar battery should always be aligned with the needs of the system operator. This is based on your own demand, the required self-sufficiency quota and the efficiency of the PV system. Each kilowatt hour, in combination with an intelligent energy management concept, can make all the difference when it comes to efficiency. Are you interested in a PV system for your home? Before going any further, use our solar power calculator to calculate your self-consumption with and without a solar battery in just a few clicks. If you run a business, it is best to contact a qualified SMA specialised company. 

What needs to be taken into account when a solar battery is installed?

When a solar battery is connected and installed, there are numerous aspects concerning safety, regulations and warranties that need to be considered. This is why it is best to leave the job in the hands of the professionals. After all, they know what needs to be taken into account when it comes to the connection point and to the technical requirements regarding connections to the utility grid and PV system. 

Can I retrofit my PV system with a solar battery?

Most PV systems can be retrofitted with a solar battery in order to increase the level of self-consumption and reduce dependency on the utility grid. The SMA Home Storage module is also compatible with all SMA hybrid inverters and can be commissioned quickly and easily thanks to a highly practical plug-and-play solution. The storage capacity can also be easily increased within two years with additional SMA Home Storage modules. The SMA Commercial Storage solution – an integrated storage solution for business owners – can also be expanded. 

When does a solar battery start to pay off?

It is unfortunately not possible to say from when exactly a solar battery will start to pay off because this depends on a range of different factors. The lifetime / service life, for example, are decisive. Local electricity prices as well as costs for electricity purchased when no self-generated solar power is available also play an important role. If the storage system is properly installed and operated and aligned with your home consumption requirements, it will start to pay off in the long term in most cases. An energy advisor will provide clarity here and examine your own personal situation. Business owners should, above all, analyse their current and future energy requirements and then choose the storage capacity and technology – this will allow them to calculate the efficiency.

What needs to be taken into account before and during operation of a solar battery?

Before a solar battery is commissioned, it must have been properly installed and inspected to ensure that it is safe. To prevent overheating, the system must be installed in a location with sufficient ventilation and stable temperatures. During operation, regular maintenance is crucial for ensuring the long service life and high efficiency of the storage system. Overcharge and deep discharging can still shorten the service life, even if the APU is designed to prevent this.

What financial incentives are available for solar batteries?

Not only the federal government but also many federal states and municipalities offer their own incentive programs for PV systems in general and, specifically, for solar batteries. Since the beginning of 2023, new small-scale plants, inverters and battery storage systems are no longer subject to value-added tax. In addition, a variety of grants are available that differ from one federal state to the next.

Here is an overview of incentive programs available in Germany, Austria and Switzerland.