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What does a salt battery storage system from innovenergy cost?

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At what point does a salt battery storage system become financially worthwhile?

At present, there are no storage systems – neither lithium-ion, nor salt or other storage systems – that are profitable without state subsidies, not in Germany and even less in Switzerland due to the low electricity prices and the poor feed-in tariff. Storage makes sense in view of optimising self-consumption or simply to reduce the electricity bill. Those who consider a storage system from the point of view of profitability should refrain from using it altogether. A storage unit in the house means more autonomy and more independence from the electricity company, and with an emergency power system even complete self-sufficiency, at least on the days when the photovoltaic system produces electricity.

An exact calculation of the profitability of a storage system depends on many factors on site, which we as storage system manufacturers cannot name. For example, it depends on the size and efficiency of the PV system which power it actually produces at which times of the year. The consumers must also be taken into account, because only the actual surpluses are fed into the battery storage system. Furthermore, the local conditions of the electricity companies are significantly involved in the calculation: Electricity tariffs during the day, night electricity as well as feed-in tariffs. An experienced energy consultant should be able to make such calculations. 

What are the dimensions of a salidomo©?

The dimensions of the salidomo© can be found in the respective technical data sheets. The salidomo© is a complete system in which everything is integrated in one cabinet. This stands very solidly on the floor and cannot tip over. Nothing has to be mounted on the wall.

What is a reasonable memory size?

The size of a storage battery depends on the output of the photovoltaic system. It is also important to consider how high the consumers in the house are. If possible, the output of the PV system should cover slightly more than the daily consumption. The surplus is then for the battery storage. 

We recommend appropriate battery storage sizes for the following installed PV systems:

  • 4 - 9 kWp PV system = 7.7 kWh salidomo© ECO salt battery storage system (1-phase system)
  • 7 - 10 kWp PV system = 9 kWh salt battery storage system salidomo© 9
  • 9 - 20 kWp PV system = 18 kWh salt battery storage system salidomo© 18
  • 18 - 30 kWp PV system = 27 kWh salt battery storage system salidomo© EXTENDED 27
  • 27 - 45 kWp PV system = 36 kWh salt battery storage system salidomo© EXTENDED 36

Can a salidomo© 18 also be upgraded to a salidomo© EXT 27/36?

Theoretically yes, but from experience we have found that the DC charging power of 3x3 kVA (9 kVA) of the salidomo© 18 is too weak for a salidomo© EXT 27/36 (27/36 kWh). More powerful inverters (3x5 kVA = 15 kVA), which have more charging power, are highly recommended. So if you want to upgrade beyond a salidomo© 18 in the future, you should consider this in advance and order a salidomo© EXT 27 with only two batteries directly.

What are the requirements for the installation site?

A salt battery storage system from innovenergy can generally be set up anywhere. The system should only be placed in a dry location, i.e. not outside, exposed to wind, weather and rain. In the cellar, in the garage, in the attic (if transport there permits), in the shed - almost anything is possible. Even a rain-protected carport can be used as an installation site. The outside temperature does not matter. The salt battery storage systems work from -20° to +60° C. 

Moisture from below is not recommended – so no clay soil. This means that the classic wine cellar is no longer an option, especially as the heat generated by the salt battery storage system means that a room temperature increase of a few degrees is not good for the culinary drop. Similarly, rooms where food is stored should not be used as battery storage space. The laundry room, on the other hand, is perfectly suitable – a salidomo© in there saves additional heating of the drying room.

Since the inverters are power electronics, a salidomo© should be stored dust-free and not near flammable materials. A barn with straw or hay is not permitted by fire regulations, nor are rooms where solvents, fuels or similar are stored. 

Furthermore, a straight and level storage area is advantageous. The salidomo© salt battery storage systems have a certain weight (see technical data sheets). Therefore, the floors should be load-bearing. Good accessibility to the storage tank itself would be an advantage. A distance of 0.5 to 1 metre in front of and to the right of the storage system should be considered for connection work. When transporting to the installation site, ensure that the doors are at least 80 cm wide. Narrow stairs may need to be checked beforehand to see whether the dimensions of the enclosure (W715 x H1538 x D680 mm) will fit through or around the corner.

The heat generated by the battery and especially the inverter are cooled by fans. Therefore, ensure a distance of at least one centimetre on the back of the storage unit. These coolers generate noise and can develop a noise level of approx. 60 decibels under full load. Thus, the salt battery storage system should not be openly audible. It should be placed in a separate room with a lockable door. An open location, such as an open stairwell or within a flat with open construction, is not recommended.

How can you use a salt battery sensibly in different seasonal weather conditions?

In summer, the days are long and the angle of the sun's rays is steep. In winter, the days are shorter. There is often bad weather with little sun and sometimes the PV modules are covered with snow. In winter, it can happen that no electricity is produced at all for weeks. This means that in summer PV systems produce about 75 % of the annual energy and in winter only 25 % of the electricity. 

This makes it clear that a correctly dimensioned storage tank is almost always filled in summer and often produces surplus, but this is rarely the case in winter. If the storage is generously dimensioned and results in almost 100 % self-sufficiency in summer, it may be that in winter the storage is "too big" and can no longer be filled on average.

The salt battery has the unique feature that you can "turn it off". You simply send it into hibernation. In many places, it makes ecological sense to switch off part of a large battery, e.g. in November to February/March. This is because maintaining the unused battery unnecessarily consumes additional energy. In spring, the battery is woken up again and ramps up again within a day without damage and is fully ready for use. No other battery technology has this capability. This means that the storage capacity can be adjusted seasonally.

Can electricity be stored in summer for the transitional periods and winter?

No. The salidomo© salt battery storage systems from innovenergy are daily storage units and not long-term storage units.

Can salt battery storage systems of innovenergy be subsidised?

innovenergy's salt battery storage systems are eligible for subsidies. In Germany, they are on the KfW and BAFA subsidy lists. In Switzerland, there is no general subsidy. Here, you have to look for the corresponding subsidy programmes at the cantonal or municipal level.

Does it make sense to charge an electric car overnight via a storage battery?


Depending on the vehicle size and type, electric cars have a battery capacity of approx. 30 kWh to 100 kWh. The salidomo© has a battery capacity of 9 kWh or 18 kWh. A house (light, cooking, washing machine etc.) consumes after sunset until the next morning approximately the amount of storage capacity that a salidomo© has – just 9 kWh or 18 kWh – depending on the size of the house and the number of household participants and consumers.

It is a simple calculation that there is usually too little storage left for an electric car. Now the larger the electric car battery as well as the daily mileage and the smaller the house battery in relation to the electric car battery, the less favourable this ratio becomes. A 9 kWh storage battery can still only deliver a maximum of 9 kWh to an electric car with 30 kWh storage. Only then is there nothing left for the household. 

From an energy perspective, charging the electric car via the house battery makes little sense, because about 30 % of the energy is lost during the charging and discharging process. And that applies to all low-voltage battery storage systems. This has something to do with the efficiency of the inverters and the storage battery. Because of these losses, it is always more economical to charge the electric car via the grid or directly via the PV system during the day in summer. It makes more sense to feed in the extra electricity at home during the day and charge the vehicle at work. 

Generally, a house battery is intended for domestic use and not for charging electric vehicles.

Is the innovenergy salt battery a salt water battery?

innovenergy's salt batteries are NOT saltWATER batteries, but salt MELT batteries on the base of sodium-nickel. You can find a more detailed explanation of this on our website under Salt Technology. In our battery comparison, you can take a look at the advantages and disadvantages of different battery technologies.

How long have innovenergy salt battery storage systems been available?

Salt battery storage systems have been around since the 1990s and have since been used successfully on a large scale in industry, especially in telecommunications in containers. You can find out more about the history of the salt battery under Salt Technology. The salt battery storage systems from innovenergy have been used as "small" systems for domestic or commercial use since 2016. Just take a look at our references.

Are there other providers of salt battery storage systems?

innovenergy is the only provider of salt battery storage systems with the integration of battery storage on the salt-nickel technology. There are no other suppliers with this technology and there will not be in the future due to contracts and patents.

What information is required to prepare a quotation?

In order to prepare an offer, the size of the photovoltaic system in kWp is required first and foremost. Furthermore, it would be helpful to know data about the night consumption and the consumers in the household. It would also be important to know which heating system (e.g. heating rod or heat pump) is used for heating and whether an electric vehicle is operated. Otherwise, we need your contact details, including email and telephone for any queries, so that we can prepare a binding offer.

What is the difference between a molten salt battery and a ZEBRA battery?

The molten salt battery (sodium nickel chloride cell) was originally invented in South Africa and developed by Anglo-American and AEG into an electric car battery for Daimler. The project name for this cell was ZEBRA (Zero Emission Battery Research Activities). This same ZEBRA cell is used in today's saline batteries by the company FZSoNick and distributed by innovenergy. For more on the history of the molten salt battery, see Salt Technology.

How big is a salt battery storage cell?

The mass of a single cell within a salt battery is 35 x 35 x 235 mm and has 95 Wh and a cell open-circuit voltage of 2.57 VA. A 9 kWh salt battery, as used in the salidomo 9, therefore consists of 100 small cells – 5 blocks of 20 cells each.

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