BayWa r.e. proves that 80 percent self-sufficiency is possible with its Plus Energy Solar House

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It is about a year since the construction of the Plus Energy Solar House in Tübingen was finished, and BayWa r.e. has positive news to report: the analysis of the first 12 months since 1 March 2015 shows that 80 percent self-sufficiency was achieved with an energy supply based on photovoltaics.

It is about a year since the construction of the Plus Energy Solar House in Tübingen was finished, and BayWa r.e. has positive news to report: the analysis of the first 12 months since 1 MaIt is important to note that this high level of self-sufficiency relates to both the electricity and the heating/hot water supply. This is because the occupants of the detached house used the power generated by the PV system both directly and to meet their heating and hot water demand. In this pilot project, BayWa r.e. used only proven standard components, which ensured a comparatively low purchase price. Furthermore, the analysis showed that the system components installed were 100 percent reliable during the whole evaluation period.

From March to October, the Plus Energy Solar House achieved self-sufficiency levels of nearly 100 percent. The output and autonomy of the house also remained at a consistently high level throughout the entire winter – in December 2015 for example, self-sufficiency of 72 percent was recorded. During this winter month, the PV system was able to cover more than half of the entire energy consumption (52 percent) directly; a further 20 percent came from PV power stored in the battery. With these figures, BayWa r.e. is able to counter the commonly held assumption that photovoltaic systems are only successful when a whole year is taken into account.

Günter Haug, Managing Director of BayWa r.e., expressed his delight at the project's success: "In designing the Plus Energy Solar House, we were motivated to find out how self-sufficient a solar domestic energy supply can be. The result was surprising even to us: self-sufficiency reaching levels of 80 percent meant that we surpassed even our own predictions. The special feature of this project is that we only used products that are already well established in the commercial market. This allowed us to demonstrate that a photovoltaic system can bring the energy transition right into individual homes."

Independence with standard components
Thanks to their many years of experience and comprehensive knowledge in the areas of system technology, design and simulations, the BayWa r.e. team of experts was ideally placed to successfully develop the Plus Energy Solar House concept, which is based on the combination of various innovative technologies. At the heart of the energy efficient house ("standard 55" according to German "KfW" requirements) – is the powerful 30 kWp PV system. In addition, a 16 kWh power pack from Hoppecke, an inverter air source heat pump from Stiebel Eltron and a 1500 litre buffer cylinder also make their contribution to the high level of self-sufficiency. The SMA Sunny Home Manager controls each component and thereby the entire energy management system to achieve maximum on-site consumption.

Equipped with the results of the first analysis, the BayWa r.e. project team is now working to further optimise the system, with the aim of increasing the self-sufficiency level of the Plus Energy Solar House yet again. Moreover, the company is expanding the concept from Tübingen to Hügelshart near Augsburg, working together with BayWa AG and its partners there to construct a residential estate with houses that all meet the Plus Energy standard. This showcase project combines energy efficient components, high energy self-sufficiency and economic benefit.

Felix Gmelin Communications Manager BayWa r.e. renewable energy GmbH
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