Photovoltaic roof systems will make an important contribution to covering the increased demand. Combined with heat pumps and seasonal electricity storage, this becomes a “dream team” for the energy transition, since the heat supply in winter can be covered with solar power from the summer – without burdening the grids or having to rely on electricity from reserve power plants.

Many buildings with photovoltaic systems (PV) feed more electricity into the grid in the annual balance than is needed to meet their own electricity and heat requirements. However, photovoltaic systems in particular without seasonal storage often feed electricity into the grid when there is already a surplus of renewable electricity.

Germany is heading for a winter power shortage

This can lead to negative prices on the electricity market, possibly to grid bottlenecks and the curtailment of photovoltaic systems. The CO2 avoidance is then lower because renewable electricity is not used.

Conversely, in the event of an undersupply of renewable energy on the electricity grid, as is often the case during the winter months, buildings with photovoltaic systems without seasonal electricity storage have significant electricity demands at a time when grid electricity is carbon-intensive. In winter 2020, the share of fossil energies in the electricity mix was more than 60 percent.

From 2024, every newly installed heating system should be operated on the basis of 65 percent renewable energy. The monthly increases in heat pumps and e-cars are in the multi-digit range, while the grid expansion and the construction of climate-friendly reserve power plants will take decades. As a result, Germany is increasingly heading towards a significant winter power shortage.

Solar power in Germany is mainly generated decentrally and fed into the distribution network level. With a locally high photovoltaic system density, this can lead to the electricity feed-in exceeding the electricity demand in the grid section.

In this case, measures must be taken to stabilize the distribution network. For example, if there is too much solar power production, photovoltaic systems can be curtailed.

In addition, in the event of an imminent blackout, the grid operator can switch off heat pumps in winter to protect the grid and thus switch off the heating without the consent of the owner. Cold residential buildings can be the result.

The aim of the further expansion of renewable energies must be to solve these problems and to ensure the greatest possible supply of local renewable energies all year round, instead of curtailing more and more renewable electricity generation.

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In connection with an increasing share of renewable energies in the power grid and local electricity requirements, the year-round, local consumption of solar power from your own roof in buildings is becoming increasingly important.

Seasonal hydrogen-based electricity storage in buildings is the solution

In addition to further grid expansion, the use of seasonal electricity storage in buildings is an option. They ensure a year-round CO2-free solar power supply for buildings by storing the excess of a photovoltaic system locally as green hydrogen on sunny days using electrolysis for the long term and making it available again in winter in the form of electricity and heat.

Compared to conventional batteries for buildings, the system offers a hundred times more storage capacity with an overall efficiency of around 90 percent. Such systems are available on the market from German production and are already in use. The installation can take place immediately. Approval procedures are not required.

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As a result, buildings can become a buffer for the power grid and counteract the shutdown of photovoltaic systems and overloading of the power grid. The decentralized storage reduces the need for expansion in the low-voltage grid. Each self-consumed and not fed-in kilowatt hour minimizes the EEG subsidy costs.

The decentralized expansion of seasonal storage in buildings also activates considerable private investments in the energy transition. In particular, technologies that rely on innovative, sustainable seasonal electricity storage in buildings should preferably benefit from future funding programs. These factors have a positive effect on the development of electricity prices, which benefits everyone.

Energetic independence and planning security through decentralized self-sufficiency

The current geopolitical crisis situation makes us acutely aware of the importance of energy independence, security of supply and price stability. Market surveys show that self-sufficiency is a key motivation for the installation of combined PV and storage systems.

The self-determined generation and use of sustainable energy is the key to a decentralized energy system that reduces the import of energy sources as much as possible. In a time of volatile development of energy prices and an uncertain supply situation, a seasonal electricity storage offers a clear predictability of energy supply and costs.

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And there is another aspect that must not be forgotten in the equation: time! In contrast to the industrial scale, a separate infrastructure does not have to be set up for seasonal electricity storage.

Therefore, homeowners can already achieve independence and planning security for their energy supply when building a new home or carrying out energy-related renovations by using renewable energy and seasonal electricity storage.

This immediately reduces fossil fuel consumption and immediately protects the environment, which is another crucial factor with less than eight years to 2030 on the carbon clock.

Big potential

Due to the modular structure, the hydrogen storage systems can also be used on a larger scale. With the further expansion of seasonal electricity storage, it will also be possible in the future for clusters that communicate with each other to be interconnected as a kind of virtual power plant.

The potential for the use of hydrogen-based home storage systems in Germany and throughout Europe is huge. In Germany alone there are around 16 million detached and semi-detached houses.

More than 100,000 new homes are built every year; Ascending trend. If you include other European markets, we estimate that there is a theoretical potential of up to 1.5 million storage systems per year in the private household segment.

With the installation of a year-round electricity storage system based on green hydrogen, the consumer is already taking control of his own secure, independent and climate-neutral energy supply with electricity and heat. The way out of the current energy crisis thus becomes a step into your own energy transition.

Zeyad Abul-Ella is the founder and CEO of the Berlin company HPS Home Power Solutions AG.

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