News: sonnen selected as the lead partner for the Cornwall Local Energy Market residential project



sonnen are working with Centrica, the UK’s largest retail energy supplier, to create the country’s largest virtual power plant to include 100 households with a solar photovoltaic system and a sonnenBatterie.

As part of the EU funded Cornwall Local Energy Market (LEM) programme, the ground-breaking project will demonstrate how households can not only produce and store their own energy but also trade energy capacity to the wholesale energy market and provide flexibility to the local grid.

The participating households will significantly lower their electricity bills by using a sonnenBatterie to optimize their consumption of solar energy. Connected by sonnen’s digital platform for virtual power plants, they will also be able to buy and store energy from the grid when prices are low or sell their energy to the grid when prices are high. The platform could even enable households to be paid when they reduce or delay their consumption from the grid.

“We’re proud to be contributing our leading knowledge in battery storage and virtual power plants in this historic project. The Cornwall LEM provides a window into an energy future that will consist of millions of decentralized producers of renewable energies. With their huge experience and extensive reach across the energy industry, Centrica is the perfect partner for this groundbreaking project.”, says Martin Allman, Country Director of sonnen UK.

The batteries installed on the LEM platform can operate dynamically using price signals. At times where there is low electricity demand and excess generation from solar PV, prices are low and it is more cost effective to store energy in the battery. At the same time, storing energy during the production peaks provides flexibility to help relieve the local grid network. If electricity demand is greater than the PV generation, prices increase and it becomes more attractive to sell the stored energy to the grid and wholesale market. In this way, the LEM platform uses price signals to provide flexibility to the grid which might otherwise be constrained at time of peak or low demand.

“Through the Cornwall LEM we want to show that a decentralized and digital energy system is already possible using today’s technology and that we don’t have to wait 10 years”, says Allman. “The energy landscape is seeing huge changes which will continue much faster than many people think. We are thrilled to be able to demonstrate the role that smart batteries in homes can play in the transition towards a secure, affordable and low carbon energy system”.

The solar PV systems and batteries will be installed by January 2018, with further testing and development of the VPP platform set to continue until Spring 2020.


sonnen closes new EUR 60 million financing round and adds Shell Ventures as new investor

sonnen is pleased to announce the closing of its latest financing round of €60 million, led by Shell Ventures and significantly supported by all existing investors. The investment enables sonnen to expand its strategy of rapid international growth and to further enhance its pioneering position as the “utility of the future.”

As a world leader in smart, residential solar storage solutions, sonnen will be able to leverage this financing to strengthen its lead and accelerate growth in markets such as the United States and Australia.

“Growing faster than the energy storage market and establishing new technologies such as energy sharing and our virtual battery pool requires continued investments. We’re very happy to receive the backing of all our investors and the commitment of a major global player like Shell to follow our vision of clean and affordable energy for everyone,” said Christoph Ostermann, CEO of sonnen.

Alongside the investment, sonnen and Shell’s New Energies division have launched a strategic cooperation agreement in areas that offer synergies between the two companies. This partnership will include innovative integrated energy propositions, enhanced EV charging solutions and the provision of grid services that are based on sonnen’s virtual battery pool.

“The great team at sonnen has succeeded in building a market-leading position in residential storage,” said Brian Davis, VP Energy Solutions at Shell. “This investment enables us to combine Shell’s power business activities with sonnen’s high quality, innovative products and business model to enhance our consumer energy offerings. This is in line with our strategy to partner with leading companies to deliver more and cleaner energy solutions to our customers.”


sonnen and ENGIE announce strategic partnership in France

_Haus_Waldfenster eco9.43 klein skv01_mb web.jpgsonnen has further expanded its international activities and entered the French market through a strategic partnership with the utility ENGIE.

ENGIE´s new PV + storage offer to its French customers – called “My Power” – will use the sonnenBatterie to enable households to cover up to 96% of its daily energy needs with self-generated power.

“We are very happy that one of Europe’s largest utilities shares our vision of clean and affordable energy. ENGIE is a company that not only talks about renewable energy but really pushes it forward. The French storage market is at the very beginning and therefore offers enormous potential. This shows that more and more people around the world want to take their energy future into their own hands and thus want to use our technology, ” says Christoph Ostermann, CEO of sonnen.

In France, around two-thirds of the population favour the installation of a solar PV system on their roof tops, and the the majority of them would like to use this electricity for themselves. For ENGIE this is a very promising market.

“We are expanding our product range with” My Power “, giving our customers the ability to store and use their own power, even when the sun is not shining. We are launching this service today, so I am very proud to announce our partnership with sonnen, using what we believe is the best storage solution on the market, “says Hervé Matthieu Ricour, Head of BtC France at ENGIE.

ENGIE, known as GDF SUEZ till 2015, is one of the largest European utilities, active in energy and services. It employs more than 150,000 people and has activities in around 70 countries. In 2017, the Group achieved an annual revenue of €65 billion. In France, ENGIE is the leading provider of green electricity (1.6 million customers) and supplies more than 11,6 million customers with energy (4 million with electricity and 7.6 million with gas).

In addition to sonnen’s important home market in Germany, the company is already represented in numerous European markets including Italy, the UK, the Scandinavian countries and Spain. In addition, sonnen is also active in the USA and Australia. Worldwide sonnen has sold more than 30,000 of its storage systems.

sonnen retains title of European market leader!

A recent analysis by EuPD Research shows that once again sonnen has held its position as the European market leader for residential battery storage.

Despite several new entrants entering the developing sector, sonnen was able to read the lead position with 21% market share followed by LG Chem and Varta.


Managing Director Sales and Marketing at sonnen, Philipp Schröder, commented: “Europe is by far the world’s largest storage market. We are therefore proud that, for the third consecutive year, we have been able to assert ourselves as a market leader in home storage against very good and well-known competitors such as LG, Tesla and Mercedes Benz Energy. This shows that our storage systems and energy services appeal to end customers throughout Europe and are thus a sure success for the installers.”

0 comments on “sonnenCommunity – solar power when the sun doesn’t shine”

sonnenCommunity – solar power when the sun doesn’t shine

sonnenCommunity_v3_EN-schmalCheck out this great video on the sonnenCommunity in action in Germany at

What is the sonnenCommunity?

The sonnenCommunity is the first-of-its-kind decentralised energy sharing community where sonnenBatterie owners share their self-produced energy with other sonnenCommunity members.

The generated energy surplus of individual sonnenBatterie systems is fed into a virtual energy pool and distributed to other members of the Community anywhere in the country – in this way, consumers become producers. A central software links up and monitors all sonnenCommunity members – while balancing energy supply and demand. The sonnenCommunity enables households to break away from their traditional energy supplier and become energy independent.

Where is the sonnenCommunity available?

Since the launch of the programme in February 2016, over 6,000 sonnenBatterie owners in Germany have joined the sonnenCommunity, with a further 500 in Austria. sonnenCommunity Italy and Australia launched in 2017 with other key sonnen markets set to follow, including the UK.

Why isn’t sonnenCommunity available in the UK now?

As the UK market battery storage market develops, we are developing our offer for sonnenCommunity UK, carrying out various trials and development work. Importantly, all sonnenBatterie units installed in the UK are future-proofed for sonnenCommunity as soon as it comes available.

You can find out more about the sonnenCommunity at



0 comments on “What makes lithium-iron-phosphate the battery chemistry of choice for the sonnenBatterie?”

What makes lithium-iron-phosphate the battery chemistry of choice for the sonnenBatterie?


At sonnen we are independent of any particular battery manufacturer and not fixed on a particular battery chemistry. This enables us to offer our customers the best available battery chemistry on the market and in our opinion this is currently lithium-iron-phosphate technology.

Lithium-ion battery technology is well known to most people for its application in mobile phones or laptops. However, there are a wide array of types of lithium-ion batteries which have varying characteristics and perform very differently in various applications. This is actually useful because each application has different requirements of what it needs the battery to do. For example, a mobile phone battery is required to perform differently in different conditions to a battery for an electric car or one that is installed in a home storage system.

At sonnen we have always used lithium-iron phosphate battery technology – also known under its abbreviations LiFePO4 or LFP. This means that one of the two battery electrodes consists of lithium iron phosphate. In most batteries used in mobile phones, laptops or electric cars, this electrode consists of a lithium-cobalt mixture such as nickel-manganese cobalt (NMC) or nickel-cobalt aluminum (NCA).

Four good reasons for lithium-iron-phosphate.

The battery units installed in the sonnenBatterie actually consist of hundreds of individual battery cells which are packed together in a battery module – 224 battery cells make up a 2 kWh battery module. The battery modules are then interconnected and can be sized in order to supply a household with stored solar energy over many hours.

In selecting the right battery technology, we look at 4 criteria which currently exclude all other batteries that we have tested.

  1. Safety.

This is an issue where in our view there can be no compromise as the sonnenBatterie is installed in our customers’ homes. the sonnenBatterie incorporate various safety features to protect against possible faults; we also ensure that we are in line with all appropriate international and national industry standards. However, this is in itself not enough for us and this is why we do not use battery technology with a very high energy density, such as those typically used in electric cars or mobile phones, such as NMC or NCA.

To understand how the batteries react in the worst (but very unlikely case) of an internal short circuit, we also carry out a nail test in our battery laboratory. Through this test we drive a nail into a battery cell to create an internal short circuit. Only when a battery is punctured and does not explode or set fire would we consider it as an option for the sonnenBatterie.

With the NMC or NCA cells tested in this way, the punctured cells ignite, burn and reach very high temperatures of over 700°C. This in turn melts the separator around the battery cell enabling it to spread to the other cells causing a chain reaction. What follows is an inextinguishable fire, as the oxygen contained in the battery material continues to burn even if the cells are submersed in water.

In our tests, even fully charged LFP battery cells do not have the same response as seen with the NMC or NCA cells. LFP cells do not ignite or reach the critical temperatures which can cause the separator to melt. This naturally becomes a very clear factor in favour of LFP batteries.

  1. Longevity and performance.

A battery storage system must perform reliably for many years for it to be a truly sustainable and economically viable proposition for homeowners. Here too, the choice of battery technology is of crucial importance.

In simple terms, a battery loses a bit of its original capacity with each charge and discharge; in effect, it can store less and less energy over time. This degradation process is minimal and continues for years until it reaches a level commonly called ‘end of life’ which can often come quite suddenly with rapid deterioration in performance. Most people have experienced this with their mobile phone, which after 2 years can barely provide for longer conversations even after completing a full charge.

The time it takes to reach this point differs considerably with each battery technology. Compared to a home battery storage system such as the sonnenBatterie, the mobile phone battery is very short-lived and usually reaches only 300-500 charging cycles. We have also tested NMC battery cells, which are often used in competitor battery storage products as well as electric cars, which achieve significantly less charging cycles. However, when used in an electric car this is not so important as just 1,000 charge cycles would provide good value when – with a range per charge of perhaps 300 km – this would correspond to a service life of 300,000 km. Many diesel or petrol vehicles would struggle to achieve this level of performance.

However, when charging a battery with solar power, 1,000 charge cycles just is not enough. In the UK (and Germany), around 250 charging cycles are required each year to enable optimum solar self-consumption. With just 1,000 cycles the battery would have to be replaced after just four years

From sonnen’s perspective a battery should last for 15-20 years to give households a long-term return on investment. For us having a high number of charge cycles is vital to be able to deliver on other applications such as using the sonnenBatterie for charging from the grid on off peak tariffs, generating revenues through grid services, or working in conjunction with micro-CHP.

The LFP batteries of the sonnenBatterie can be charged and discharged more than 10,000 times and still have 70% of their output capacity – this is market-leading performance. Even after 15,000 cycles, batteries will still have over 60% of their capacity. In this way, lithium-iron phosphate provides us with a solution which allows our customers to use their system for various applications for the long term.

  1. Proven technology.

Lithium-iron phosphate technology has been around for more than 15 years and has proven itself in applications such as buses and even in submarines. Since the company was founded in 2010, sonnen has exclusively used lithium-iron phosphate and has since sold over 25,000 sonnenBatterie systems. One of the principal suppliers of our battery modules is Sony, which launched the first commercial lithium-ion battery in 1991 and has since developed its own lithium-iron phosphate technology. Sony offers a best in class, environmentally friendly battery module with state-of-the-art design and highest quality mass production. What’s more, the strong international brand gives customers even greater trust and confidence that they are investing in a quality product.

  1. Environmental compatibility.

Lithium-iron phosphate is the only battery material which, in its chemical composition, also occurs as a natural mineral. Remember that a battery consists of two electrodes: one of them is graphite while the other is a nickel-cobalt mixture or even lithium-iron phosphate. In our batteries there are neither cobalt nor nickel, both of which are regarded as toxic heavy metals. The mining of cobalt has also been a cause for concern. Whilst cobalt used in Europe is often imported from Canada or Australia, a large part of the production is also located in the Congo, where the raw material is mined under questionable circumstances.

In summary, it is only when a battery technology fulfills all these four features that we use it in our sonnenBatterie systems. In the future new battery technologies will be developed and become commercially viable – offering improved performance, longevity and safety at a lower cost. However, for now only lithium-iron-phosphate hits the mark to be included in a sonnenBatterie.