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Charging with green electricity on a grand scale

5/26/2023 / Mainz-Kostheim, Germany
Extraordinary solar charging park uses project inverters from Fronius.

5 million kilometers of emission-free driving

Charge your electric car conveniently and economically while doing your shopping. This is a wish come true for shoppers in Germany’s Mainz-Kostheim area. Next to a large neighborhood shopping center, SUN2CHARGE GmbH operates a solar charging park that generates 100% of its own solar power, revolutionizing the solar-powered infrastructure for electric mobility in the surrounding area. The large-scale project was constructed exclusively with Fronius inverters.

The solar charging park is the first of its kind in Germany and a truly pioneering project in terms of sustainable economic efficiency. A photovoltaic system featuring an impressive 2,300 modules as well as 16 km of PV cable and 1 km of data cable was installed on the roofs of the surrounding buildings. The system generates approximately 900,000 kWh of solar power annually – a gigantic amount of energy that could power a single electric car for an incredible 5 million emission-free kilometers. 

» This project is quite singular and has never been built this way before in Germany. «

Christoph Hesselmann, Opel Energy GmbH – charging park construction

Fronius inverters form the core of the high-output, 1,000 kWp PV system

12 Fronius Tauro inverters and 2 Fronius Symo inverters were installed for the large-scale project. The ideal choice for this exceptional project, these rugged project inverters not only offer maximum flexibility in system design but also consistently deliver maximum output even under the most adverse environmental conditions – and also don’t require any overhead protection outdoors. What's more, the Fronius inverters used can be quickly installed and maintained. If necessary, only the replacement components need to be replaced on the Fronius Tauro, and not the entire inverter. This makes it even more economical to operate the large-scale PV system for the solar charging park, while also trimming total system costs to a minimum.

Charge up extraordinarily cheaply with the sun

The concept for the Mainz-Kostheim solar charging park has a unique selling point: instead surplus solar power being fed into the public grid, it gets stored at the site in large battery storage units with a capacity of 560 kWh. “This lets us ensure that more than 80% of the electricity we put into the electric cars is generated by the sun,” explains Christoph Hesselmann of Opel Energy GmbH, which built the charging park. In the next few years, this is expected to increase to a full 100%.

And all customers benefit: the solar power is available 24 hours a day at especially economical prices, since the costs for charging electric cars depend on the solar energy produced. When the storage units are full and the sun is shining, the price for charging can be significantly lower.

Optimal charging capacity for the environment

10 charging stations with 2 charging points each are now available to customers of the local shopping center for charging their electric cars while they shop. To achieve this, the output of the charging infrastructure was optimized to match the way the typical shopper charges: “After a 45-minute shopping trip, an electric vehicle is charged on average from 20% to 80%. So the charging points are ideally aligned to use the shopping time for charging the electric car,” says Christoph Hesselmann, explaining the choice of charging infrastructure. While systems with even higher charging capacity are available, they would not directly enhance the added value of the charging park and would instead merely result in higher investment costs. 

100% solar power, 100% independence

Only a minimal part of the public infrastructure is used for operation of the solar charging park. This makes it a prime example of a completely self-sufficient micro-power solution. Falling back on the public electricity grid will only be necessary if the PV system fails to produce a yield or all the storage units are completely empty – an unlikely scenario, according to Christoph Hesselmann: “Thanks to our intelligent power management, we don’t expect this to happen, especially in the first few years. So we're basically functional even if the infrastructure around us collapses.” The much-discussed and often-cited phrase “grid overload” in connection with electric mobility therefore plays no role at the solar charging park in Mainz-Kostheim. That’s a reassuring thought for the operators, but also for the users from the surrounding area. 

Challenge accepted

With its courage and openness to new ideas, Fronius was able to impress the builders of the charging park right from the start. While other companies strictly refused a project at such a large scale, Fronius employees were immediately enthusiastic about the unprecedented project because it perfectly matches our vision of 24 hours of sun.

In the 14-month planning phase that followed, our Fronius project team demonstrated their impressive level of expertise and focus on service. Another decisive argument for working with Fronius was the regionality and the entirely European manufacture of our products and product components. “The cooperation with Fronius was flawless. All of the technology worked without a hitch and the support was excellent. I have had very different experiences in the past with much smaller projects,” says Hesselmann, enthusiastically summing up the first joint project between Opel Energy GmbH and Fronius. 

» The contacts at Fronius were the first to say, ‘We think that's exciting; we can make it work.’ «

Christoph Hesselmann, Opel Energy GmbH – charging park construction

Conclusive answers for the future

We’ve found conclusive answers to all the things currently seen as challenges in connection with electric mobility – answers we believe are absolutely visionary.” Christoph Hesselmann

Everyone involved was able to take away valuable experience and a lot of positive feedback from the pioneering project with a EUR 1.8 million budget. Building on this, many more charging parks of this kind are set to follow – again using durable Fronius Tauro and Fronius Symo inverters, which feature the ideal properties for commercial projects when it comes to efficiency, longevity and service. We are proud of the successful implementation of this exceptional large-scale project for comprehensive electric mobility that is moving us all forward.

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