Costs, benefits and types • NYHEDER.AT

Basically, electricity storage for solar cells is a oversized batterythat likes a battery repeatedly loaded and unloaded maybe. The electricity generated by the solar system is stored during the day and consumed again in the evening or night. If more electricity is produced than the storage can absorb, this surplus is fed into the electricity grid.
Simply put, inside a battery are atoms that can store and donate electrons. These are nothing but the smallest particles that can generate electricity through movement. A single battery is referred to as a battery cell – several together form a battery storage system.

Without power storage, you can only use the self-produced solar energy when it is produced – i.e. during the day. So if you are at home a lot, or if you can charge your e-car during the day, you can do without storage. If not, then you can significantly increase your own consumption with a storage tank. Because then he can PV electricity is also used in the evening and at night will. Since electricity is currently relatively expensive, you can Significantly reduce electricity costs.

If you value a lot independence from this point of view, the acquisition also makes sense. Because in case of a blackout then you are on the safe side (but then, in addition to storage, you must also have a hybrid inverter and a switch box).

It is important before you buy one accurate bill to create. How much power does my solar system generate, how much can I use immediately and how much is left that I need to cover through an electricity provider. Then you have to calculate how big the power storage should be. You can of course use it to increase your own consumption, but memory costs money and installation costs are often not included in the calculation. So it might be not financially is to make this rather large purchase. In any case, you should consult an expert – who also knows all the subsidies you can claim. The currently high electricity costs make the purchase more economical than beforenevertheless, it may not be economically viable.

What types are there?

Basically, at the current state of the art, there are two storage technologies ready for the market for home use: Lithium-ion storage and Salt water batteries (sodium batteries). apart from that there is Redox flow storage or hydrogen storagesome of which are still at the research stage or suitable for larger storage volumes.

Lithium-ion storage

There are different types of lithium-ion storage. The most common variants are lithium polymer, lithium iron phosphate and lithium titanate batteries. Above all, these memories are characterized by the fact that they can be loaded and unloaded frequently and one more high efficiency display. Besides, they have a high energy density. A possible problem however it is Overheating during charging of storage. But modern, intelligent charging systems largely solve this. Lifetime is usually stated in charge cycles. On average, modern systems manage between 5,000 and 7,000 cycles. If you consider that the electricity storage units achieve between 100 and 200 cycles per year in conjunction with a solar system, a storage unit lasts practically forever.

Salt water battery (sodium battery)

Salt water batteries (sodium batteries) are newer on the market, and therefore there are even fewer land time values ​​for them. The advantage of these systems is theirs environmental friendlinessbecause they are based on salt water and contain no polluting materials or critical raw materials. So are they easy to recycle. Efficiency is currently around 80 to 90% and energy density is lower – meaning they take up more space.

How big should the battery be?

When dimensioning electricity storage, it should be ensured that the storage utilizes its usable capacity efficiently to avoid excessive costs. At the same time, the storage should not be too small, so that sufficient own PV power is available at all times if required.

There is a to rough initial planning Approximation formula: 1:1:1. This means that if the annual electricity demand, the electricity produced by the solar plant and the storage capacity are in a 1:1:1 ratio, then around 60% of the self-produced electricity can be used directly.

For a rough calculation, it is possible to make an initial assessment free of charge at However, this cannot replace planning by a specialist.

The calculator shows the following example for a single-family house:
In a building with an annual electricity consumption of 4,000 kWh and a solar cell system with an electricity production of 4,000 kWh, the optimal storage size is 4,000 Wh, i.e. 4 kWh (net storage capacity). A significant increase in memory does not pay for economic reasons.

How much does a power saver cost?

The acquisition costs of an electrical storage for a single-family house cannot be generalized, as key figures such as the usable storage capacity, the maximum discharge capacity and the number of full cycles are also important. In plain language, this means: The larger the memory, the higher the cost. If you find out about lithium storage, you must have a capacity of up to 5 kWh with one Net price from 1,100 to 2,100 euros per kWh Calculate. You then need to add VAT and installation costs. That’s the way it is no small purchaseas you have to do here.


But of course – especially during the energy transition – there are also subsidies for that. 1. The possible ones can be found at federal grants and 2. the further state subsidy. The federal funding relates to the construction or expansion of solar installations. Investment grant is a one-off grant for PV and power storage systems. For solar systems, each individual kWp, in the case of electricity storage, each individual kWh is supported with a specific subsidy rate (€/kWp or €/kWh). In the case of state subsidies, there is only a pure subsidy for electricity storage (i.e. without a solar installation installed) only in Vienna at a rate of EUR 200 per kWh.

Ellager: What should you pay attention to when buying?

When purchasing a battery storage system for the solar system must Battery life (loading cycle) plays a not entirely insignificant role. After all, this storage tank must last for many years and be able to be charged and discharged as often as possible. Most manufacturers now guarantee that their storage systems will withstand the average charging cycles of the solar system per year. This ensures that the individual components in the system have the same lifespan.

It doesn’t matter either Storage efficiency. As little solar energy as possible should be lost. This can happen through self-discharge or conversion loss. Therefore, you should compare different systems to find the most effective one.

In order to function sensibly and not be unnecessarily expensive, the memory must absolutely correct size be. Too small is of little use, and too large is too expensive and never pays off.

What happens in the event of a power failure?

Many new systems have emergency features. This means that you can continue to supply your own house in the event of a power failure. It is therefore possible to use the system as it is called isolated solution to operate. If you want this function, you should ensure that this is technically possible when purchasing the memory. Whether the storage can still be recharged when the supply from the electricity grid is lost is also a question that needs to be clarified. This is not the case with some models (operation as an isolated solution is therefore only possible to a very limited extent).

Power storage for PV: advantages and disadvantages


The advantages are obvious: you can use more of your own power, so you can Reduced electricity costs will. In addition, this will CO2 footprint smaller and environment considerably eased.


But the same applies here: no light without shadow. Ellager also has disadvantages. If you oversized is, they cost a lot and do not bring more self-supply (the memory cannot store more than the PV system supplies). Besides, they also need place. Unfortunately, there is a possibility that the ecological balance will become negative. But new plants now save more energy than their production uses – but the warehouse must be dimensioned correctly. To Recycling may possibly problematic be.

What does the future hold?

For private use, the currently available power storage devices are quite innovative. Many start-ups are exploring new opportunities, but they are all in experimental stage and there is no telling which technology will prove to be truly mass market.

For large storage systems, things tend to go in a completely different direction, namely not to store the electricity (as this is always associated with large losses), but rather to store it to generate gas, hydrogen or heat with electricity. These products can then be transported and stored with almost no loss.

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