Solar storages

A solar storage system, also known as a battery storage system or energy storage system, is a system that stores excess electrical energy from a photovoltaic system. This energy is used later, for example at night or when the sky is cloudy, when the solar system produces little or no electricity.

The solar storage system usually consists of one or more batteries made of materials such as lithium-ion, lithium iron phosphate or lead-acid. Lithium-ion batteries are particularly widespread due to their efficiency, durability and capacity.

How does a solar storage system work?

During the day, the photovoltaic system generates electricity when the sun is shining. The electricity produced is initially used for household consumption. Excess electricity that cannot be used directly is loaded into the solar storage system. This process is carried out via an inverter, which converts the direct current (DC) from the solar system into alternating current (AC) for the household.

If the electricity demand exceeds that of the solar system, for example at night, the solar storage system supplies the stored energy back to the house. If the storage system is empty, additional electricity is drawn from the public grid. Modern systems also often work with intelligent controls that optimize energy flows and maximize self-consumption.

Overall, a solar storage system helps to make the use of solar energy more efficient and independent, and enables more of the electricity generated to be used yourself instead of feeding it into the grid.

Solar storage, also called battery storage, stores excess energy from photovoltaic systems for later use. There are different types of solar storage that differ in technology, cost and performance:

1. Lithium-ion batteries

These are the most common solar storage systems. They are characterized by high efficiency, a long service life (approx. 10-15 years) and a high energy density. They are particularly suitable for households with high electricity consumption as they are space-saving and durable.

2. Lead-acid batteries

Lead-acid batteries are the oldest technology and cheaper to purchase. However, they have a shorter service life and are less efficient than lithium-ion batteries. They are more suitable for small applications or limited budgets.

3. Saltwater batteries

This environmentally friendly technology uses non-toxic materials and is fully recyclable. However, saltwater batteries are less common and have a lower energy density, which makes them attractive for smaller applications or environmentally conscious users.

4. Redox flow batteries

This technology is particularly suitable for large storage solutions. It is based on liquid electrolytes and offers an unlimited number of cycles. However, they are more expensive and less space-saving, which is why they are more likely to be used in the industrial sector.

5. Hydrogen storage

These store energy in the form of hydrogen, which is later converted into electricity. They are suitable for long-term storage and are promising for the future, but are currently expensive and technically demanding.

The choice of the right storage depends on individual needs, budget and desired area of ​​application.

The size of the solar storage depends on several factors that must be calculated individually. First of all, the daily electricity consumption is crucial. A rough rule of thumb is that the solar storage should have a capacity of around 1 to 2 kWh per person in the household. This means that for a household with 3 people, a storage unit with a capacity of 3 to 6 kWh could make sense.

Calculating the right size

To calculate the ideal size more precisely, the self-consumption of the solar power system must be taken into account. If, for example, you have a photovoltaic system with an output of 6 kWp and generate around 20 kWh of solar power every day, you can use a storage unit to increase your self-consumption and maximize the proportion of electricity you use yourself. In this case, a storage unit of 5 to 10 kWh could be the right choice.

Taking emergency power functions into account

If you also want to use the solar storage unit for emergency power purposes, you should adjust the storage size accordingly. A larger storage unit ensures that you have enough energy available even during a power outage. In such cases, a storage unit with more than 10 kWh can be useful in order to remain self-sufficient over longer periods of time.

Conclusion

The size of the solar storage unit depends on the power consumption, the solar system and individual needs. A precise calculation by a specialist can help to determine the optimal size and benefit from a higher self-consumption rate in the long term.

A solar storage system can be financially worthwhile, especially when you consider the long-term savings and the increasing independence from electricity providers. However, a number of factors must be taken into account to assess profitability.

Investment costs and payback

The purchase costs for a solar storage system vary depending on the size and technology, usually between 5,000 and 10,000 euros. In addition, there are the costs for installation and possible maintenance. The payback period, i.e. the period in which the investment pays off through savings on the electricity bill, is usually between 8 and 15 years.

Self-consumption and savings

A major advantage of a solar storage system is the ability to use your own solar power directly instead of feeding it into the grid. This means that self-consumption can increase from around 30-40% to up to 70-80%. The more electricity from your own photovoltaic system is used, the less has to be bought from the electricity provider, which leads to significant savings.

Subsidies and tax relief

In many countries there are subsidy programs and tax reliefs that can reduce the purchase costs. In Germany, for example, investment grants or low-interest loans from the state or banks can be used to make the initial investment easier.

Long-term independence

Another financial advantage of a solar storage system is independence from rising electricity prices. In the long term, storage systems offer a stable calculation of electricity costs.

Overall, a solar storage system can be financially worthwhile if the conditions are right and the use is optimally planned.

The lifespan of a solar storage system depends on various factors, in particular the type of storage system, use and maintenance. In general, modern solar storage systems can achieve a lifespan of 10 to 20 years.

Types of solar storage systems and their lifespan

The most common solar storage systems are lithium-ion batteries and lead-acid batteries. Lithium-ion storage systems are the most common and usually have a lifespan of 10 to 15 years. These batteries are characterized by high efficiency, low maintenance and a greater number of charging cycles, which extends their lifespan.

Lead-acid batteries, which are slightly cheaper, have a shorter lifespan of around 5 to 10 years. They require more maintenance and are more prone to lower performance over time.

Factors that affect service life

• Charge cycles: A charge cycle describes the complete charging and discharging of the storage unit. The fewer cycles a storage unit goes through, the longer it lasts.
• Temperature: Temperatures that are too high or too low can have a negative impact on the service life of a storage unit.
• Maintenance: Regular maintenance and correct handling of the system will help extend its service life.

A solar storage unit loses capacity over the years, but many models are designed to remain functional even after many years, even if the maximum storage capacity drops slightly.

The cost of a solar storage system can vary greatly depending on several factors such as storage capacity, type of storage and brand. In general, prices depend on the size of the system and the individual needs of the household. A solar storage system must be large enough to store the excess solar power generated during the day so that it can also be used in the evenings or on cloudy days.

The most common solar storage systems are lithium-ion batteries, which usually require a higher initial investment but offer a longer lifespan and higher efficiency. Older technologies such as lead-acid batteries are often cheaper, but they have a shorter lifespan and are less efficient compared to modern lithium-ion storage.

For a typical household with a photovoltaic system, the cost of a solar storage system can significantly increase the cost of installing a solar system. However, the costs are recouped through the savings on electricity bills as more solar power can be used directly on site. In many countries there are also government subsidies or grants that can reduce the initial costs.

In summary, the purchase of a solar storage system is a long-term investment that can pay off in the long term due to independence from external electricity suppliers and rising energy costs.

Yes, it is generally possible to retrofit a solar storage system into an existing photovoltaic system (PV system). This offers a sensible way to optimize your own consumption of solar energy and to become more independent of rising electricity prices. However, there are a few points to consider.

Compatibility with the existing PV system

Before retrofitting a solar storage system, you should check whether the existing PV system is compatible with a storage system. This means that the inverter output, the output of the solar system and the storage capacity of the system must be coordinated. In some cases, the inverter must be changed or adjusted to enable communication between the storage system and the PV system.

Planning and installation

Retrofitting a solar storage system should be carried out by a specialist. The storage system must be connected to the electrical installation and correctly configured to ensure safe and efficient use. An additional meter is usually required to accurately measure self-consumption and monitor the feed-in to the grid.

Advantages of retrofitting

By retrofitting a solar storage system, the proportion of self-generated electricity used in your own household can be significantly increased. This reduces the electricity bill and increases independence from the power grid. In addition, the efficiency of the PV system is improved overall.

In summary, retrofitting a solar storage system is a practical and worthwhile solution for optimizing the use of solar energy.

A solar storage system offers numerous advantages that are both ecologically and economically interesting. One of the biggest advantages is the optimization of self-consumption. The storage system allows you to use the solar power generated during the day for your own consumption in the evenings when the sun is no longer shining. This means you are less dependent on the power grid and can significantly reduce your energy costs.

Another important advantage is independence from the power grid. With a solar storage system, you can use the electricity generated yourself and are less affected by rising energy prices or power outages. A solar storage system offers additional security, especially in regions with unstable power grids or frequent power outages.

In addition, solar storage systems help to reduce CO2 emissions because they increase the proportion of self-generated, renewable electricity. By using less electricity from fossil sources, you are making an active contribution to environmental protection and the energy transition.

Another advantage is the emergency power function that many modern solar storage systems offer. If there is a power failure, the storage system can continue to supply energy and power important devices such as refrigerators or heaters.

In summary, a solar storage system offers high efficiency and flexibility, enables better use of renewable energies and contributes to long-term cost savings.

When the solar storage is fully charged and can no longer absorb any more energy, there are several options for how to deal with the excess electricity:

• Feed electricity into the public grid: The most common solution is to feed the excess electricity into the public grid. In many countries, the owners of solar systems receive compensation for this through the so-called feed-in tariff. The amount of this compensation varies depending on the country and the time of installation.
• Maximize self-consumption: In modern solar systems with an intelligent energy management system, the excess electricity can also be used to supply other devices in the household. For example, heating elements for hot water boilers or heat pumps can be powered by excess energy.
• Storage overflow and smart home technologies: Some systems allow excess electricity to be stored in other battery storage units or devices within the home that are able to use the energy when it is needed.
• Using electricity at a later time: Some of the excess electricity can also be stored in the form of electricity credits on a smart meter that can be accessed later to meet demand when the solar system does not produce enough energy.

The decision on how to use excess energy depends on the specific installation, available technologies and regional regulations. In any case, smart use of excess energy contributes to the efficiency and profitability of solar systems.

Yes, in Germany there are government subsidies for solar storage to support the expansion of solar power systems and their storage. These subsidies aim to promote the use of renewable energies and advance the energy transition. There are several programs at federal and state level that help households and companies to make the purchase of solar storage financially easier.

A central funding mechanism is the KfW program 270 (Kreditanstalt für Wiederaufbau), which offers low-interest loans for the purchase of solar storage. This program supports both the installation of photovoltaic systems and the integration of storage. In addition, there are sometimes grants that do not have to be repaid in order to reduce investment costs. However, these subsidies are often tied to certain conditions, such as the type of storage or the size of the photovoltaic system.

Another funding program is the Federal Funding for Efficient Buildings (BEG), which supports both photovoltaic systems and the storage of solar power. This particularly supports private households and companies that want to optimize the energy efficiency of their buildings. Grants or loans can also be applied for here.

In addition to federal funding, many federal states offer their own programs that are specifically tailored to the needs of the respective region. These programs often vary in the amount of funding and requirements, so it is worth checking the specific funding options in your own federal state.

The state funding helps to make solar storage more economical and to make investments in a sustainable energy supply more profitable more quickly.