Candidate 3, Solartechnik Mitteldeutschland: Innovative PV and CHP project for tenanted apartment buildings


The energy transition is a huge challenge, a challenge that Chris Werner of Energy Consulting is convinced he is rising to in an exemplary, if small, way. With Daniel Zschuckelt of Daniel Zschuckelt Solartechnik (Solartechnik Mitteldeutschland), he is equipping not just a single multi-family dwelling in the Passendorfer Schloss residential development with combined renewable energy sources, but several such units, and integrating them into a microgrid. "We have implemented all the major trends needed for the energy transition," says Werner. This will reduce energy costs, according to his calculations, by 15% over what it would cost to supply the housing units through the local utility.

The multifamily building with 14 apartments, 12 units in a row house, and six additional residential units are currently under construction and will be supplied starting this fall by an 80 kW east-west PV plant and a 20 kilowatt pellet-fired cogeneration plant. The housing complex also has a smart meter network from Discovergy. "There is real-time consumption monitoring," says Werner, "which opens up the black box of energy consumption." Some studies show that this kind of transparency makes a critical difference to energy savings and efficiency. In the USA, successful start-ups like Opower and Bidgely base their business models precisely on that idea. In this case, the concept is being realized not in a single-family home but for residents of a multifamily dwelling.

A unified concept of electricity and heat

In the project, the heat and power supplies are implemented together. In addition, there is a large thermal storage unit. It makes use of excess solar power. "There is no need to feed unused solar power into the grid," says Werner. The project is not optimized for electricity or heat, but rather optimized to the energy system as a whole. The PV system acts as the heart of the energy system. The cogeneration plant and heating with excess or unused solar power are controlled based on PV production.

The challenges are in the details. The same goes for regulatory issues, which are not always clear in Germany for new business models. Discussions with regional regulatory authorities preceded implementation of the project. The residents will now receive their own power supply agreement; according to the calculation, 75 percent of the electricity will be produced on-site and, added to the heat supplied, the system will deliver 85 percent of the residents' total energy. The development could be even more self-sufficient were it not for the fact that the combined heat and power plant will be shut down during the summer to avoid higher costs for residents. To meet electricity demand not covered by the PV system, green power will be purchased.

A business model template for others

Because the project not only saves money for those who live in the housing units, but also generates returns for its investors, the Passendorfer Schloss residential development could be a model concept for demonstrating how to master the challenges of the energy transition. For one thing, there is broad agreement that tenants in multi-family housing must have the opportunity to benefit from the energy transition and that there must be participation similar to self-consumption for owners of single-family homes. It is also clear that to achieve PV expansion targets, the roofs of multi-family dwellings will have to be used to a large extent for photovoltaics, an application for which business models have often been lacking.

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Werner even sees a possibility of his project serving as a template for a business model power utilities could use.

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Candidate 1, maxx-Solar:

What does the school earn with the rented PV installation if the self consumtion rate is 90%?

(400, 800 or 1200 Euro)

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Candidate 2, BIG:

How many containers are required to build an urban rigger?

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Candidate 3, Solartechnik Mitteldeutschland:

How much do the inhabitants of the 16 houses save thanks to the almost-autonomous mini smart grid?

(5% energy costs, 10% energy costs or 15% energy costs)

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Candidate 4, Intellisol:

What percentage of the dealership’s energy use is covered by the Intellisol PV installation?

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