Solar-Log™ Guarantees the Upper Feed-in Limit

06. February 2019

Solar technology provider Solar-Energie Andresen GmbH (sea) installed two rooftop solar PV plants at Waagen-Wulff GmbH in Flensburg. Each plant is equipped with a Solar-Log™ PM Box 2000 to guarantee compliance with the feed-in limits specified by the regional energy supplier. Depending on requirements, the two-stage system, consisting of the Solar-Log 2000 PM+ and a PAV,E guardian, regulates the power input of one of the two plants. This ensures that the electricity being fed in to the grid does not exceed the maximum amount allowed by the energy supplier. The system is being used in this form for the first time in Germany.

Geislingen-Binsdorf, February 6, 2019: Since 2010 the company Waagen Wulff GmbH has been producing electricity with an east-west oriented 137 kWp PV plant. 100% of the electricity produced is fed in to the grid. The managing directors Mathias Wulff and Thomas Wulff attach great importance to sustainability. In 2018, an additional 81 kWp PV plant was installed. It guarantees the supply of clean PV electricity to the building (consumption of self-produced power). Outside business hours, the surplus electricity from the new PV plant is also fed into the grid. The difficulty is that due to the company's own transformer, there is an upper feed-in limit of 125 kW. If both plants are fully fed into the grid, for example on a sunny weekend, this limit is easily exceeded. The solar technology provider Solar-Energie Andresen GmbH (sea), the energy management professional Solare Datensysteme GmbH (SDS) and the SDS service partner Sibert Solar Ltd solved this problem together. In order not to exceed the maximum feed-in power, they installed the Solar-Log™ PM Box 2000 from SDS.

The connected Solar-Log 2000 PM+ measures the power consumption as along with the production of the two PV plants. It regulates the entire feed-in to a maximum of 125 kW. The 81 kWp PV plant not only covers the company's own consumption (classic 0-export), but can also feed in the difference between the feed-in quantity of the 137 kWp PV plant and the fixed upper limit against payment. Regardless of this, the integrated PAV,E guardian continuously records the output at the feed-in point. In the event of load shedding or failure of the feed-in control, the PAV,E guardian disconnects the 81 kWp PV plant from the grid. The maximum power input of 125 kW is therefore not exceeded at any time.

In addition to the feed-in control, the Solar-Log 2000 PM+ also monitors and remotely controls the PV plant as expected. This means that the entire area of energy management is covered by a single system.

SDS already offers a solution to the application rule VDE-AR-4105, which will come into force in April. This rule allows an installed capacity deviating from the connected load.


Statements to the project:

Sascha Dellmann, Technical Project Manager at Solar-Energie Andresen:
"With the Solar-Log™ PM Box, we can offer PV plant operators who are tied to a feed-in limit an absolutely safe solution. The energy provider is guaranteed that no more than the maximum feed-in quantity it has set will flow into the grid."

Christoph Zeitz, Solar-Log™ Project Engineer:
"This project is a great example of how best to meet the feed-in cap. Together, we were able to implement it optimally and have installed a solution that helps numerous PV plant operators with a similar starting situation.”

Andy O'Leary, CEO of Sibert Solar Ltd.:
“In Great Britain, the Solar-Log™ PM Box has been used successfully for some time. I am very pleased that it has now also been installed in Germany".

Jochen Niedermeyer, network planning at Stadtwerke Flensburg
"The overall solution convinced us, which is why we agreed to an installation. Guaranteed compliance with the upper feed-in limit - that's exactly what we need to prevent unwanted grid export. This enables the plant operator to effectively use as much solar power as possible himself."

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