Go to Content

Demonstration Operation of a Residential System that Combines Solar Panels, Storage Batteries, Heat Pumps, and HEMS Begins
-Establishing an “Energy Self-Consumption Model” for Local Production and Consumption of Solar Power in Germany-

May 31, 2016
New Energy and Industrial Technology Development Organization (NEDO)

As part of the “Smart Community Demonstration Project in Germany”, NEDO, in collaboration with NTT DOCOMO, INC., NTT FACILITIES, Inc., Hitachi Chemical Company, Ltd. and Hitachi Information & Telecommunication Engineering, Ltd. has begun demonstration operations of an integrated system that combines solar panels, storage batteries, heat pumps, and HEMS (Home Energy Management System).

The project is taking place at a demonstration site in the city of Speyer in the German state of Rheinland-Pfalz at an apartment complex (two buildings; 16 units each). By combining advanced Japanese electrical storage, heat pump water heater-based thermal storage, and information and communications technologies, the project aims to build a system to improve the local consumption rate of electricity produced by photovoltaic (PV) panels, and to establish a new model that contributes to the stable operation of the power system while expanding the economic benefit for customers.

A diagram of the project system & The demonstration site

1. Project Overview

In Germany, renewable energy currently provides more than 20% of the total power demand, and the federal government has set targets to increase the ratio of renewable energy to 35% by 2020 and to 80% by 2050. However, with the reduction in cost of PV power generation, grid parity*1 has already become apparent, thus practically ending the Feed-in Tariff program in Germany. Because of this, the benefits for customers who sell the electricity generated by their PV power generation equipment to the electric utilities have been diminished. In addition, reverse power flow*2 from PV power generation is difficult for the electrical grid to handle due to the limited capacity of distribution lines, and there are inverter output suppression measures already imposed on residential PV power generation equipment. Therefore, it is becoming a pressing issue to build a system where PV-generated power is consumed by the producing households as much as possible, decreasing the need to sell the power to electricity companies.

In this context, NEDO, in collaboration with the German city of Speyer, which has a goal of satisfying 100% of energy supply for heat and electricity using renewable energy, along with Stadtwerke Speyer GmbH (SWS) and GEWO Wohnen GmbH, agreed to start a smart community demonstration project focused on realizing a new “energy self-consumption model” in Speyer. On July 23, 2015, a Memorandum of Understanding (MOU) was signed between NEDO, the city of Speyer and SWS to begin the project.

Operation has now begun following the completion of the demonstration systems integrating solar panels, storage batteries, heat pumps, and HEMS at an apartment complex (two buildings; 16 units each). The demonstration system predicts the PV power generation and energy consumption (electricity and heat) based on data on the amount of solar radiation and the load pattern of each household. The HEMS control logic is designed to minimize both reverse power flow to the power system and energy costs for consumers based on a virtual power pricing model, thus optimizing storage battery and heat pump control. Additionally, the two apartment buildings are divided into "household unit" and "building unit" types in order to maximize the energy self-consumption rates for each kind of system. Over the course of approximately two years (until March 2018) of operating the demonstration system in a real-life environment, the project will assess the effectiveness, reliability, and economic efficiency of the new system.

2. The Operation Commencement Ceremony

To commemorate the start of operations of the demonstration site, an operation commencement ceremony was held in Speyer, Germany on May 30 (local time). The ceremony was attended by NEDO Executive Director Makoto Watanabe, Embassy of Japan in Germany Ambassador Takeshi Yagi, Consulate General of Japan in Frankfurt Consul general Takeshi Kamiyama, NTT DOCOMO Senior Vice President Kouji Furukawa, NTT FACILITIES Senior Vice President Tadahito Aoki, Hitachi Chemical Vice President and Executive Officer Misao Nakagawa, Hitachi Information & Telecommunication Engineering Vice President Hidehiko Iwazaki, Speyer City Mayor Hansjörg Eger, SWS Managing Director Wolfgang Bühring, GEWO Managing Director Alfred Böhmer, as well as other officials and residents participating in the project.


  • *1 Grid Parity
    The point at which the cost of power from renewable energy sources becomes equal to the price of the electricity purchased from the grid.
  • *2 Reverse Power Flow
    The flow of electricity from a non-utility generating source to the electrical grid. This happens when the amount of electricity generated from residential power generation equipment such as PVs or wind turbines operated and connected to the grid is greater than the amount of power consumed by the generating party.

3. For more information, please contact:

(Regarding this News Release)
NEDO Smart Community Department
Contact Persons: Yamakawa, Kurosawa
Tel: +81-44-520-5274­

(General Inquiries about NEDO)
NEDO Public Relations Department
Contact Persons: Sato, Sakamoto, Kohtsusa, Fujimoto
E-mail: nedo_press@ml.nedo.go.jp