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KfW40+ house Energy Efficient Projects from Germany

Nov. 2022

KfW40+ house: Energy Efficient Projects from Germany


Currently, Europe is facing an unprecedented energy and power crisis.

Under the influence of the shortage of natural gas supply and the heat, electricity prices in Europe have skyrocketed. In the first week of August, the electricity price in Germany even reached a record 101.15 Euro cents/kWh at one point.

Soaring electricity prices in Europe are exacerbating the cost-of-living crisis, prompting governments to offer support to households and businesses to save energy. In fact, Germany has long had relevant policies and experience in energy efficiency, the most important representatives of which include KfW Efficiency House.

So what is KfW Efficiency House?


The concept of "Efficiency House" as an energy standard for buildings and the associated classification of KfW Efficiency house were developed by the German Federal Ministry for Energy, Building and Urban Development (BMVBS) and the then Federal Ministry for Transport, BMVBS jointly formulated. It describes a particularly energy-saving construction and renovation standard. The buildings hardly lose any heat and cover the low demand very efficiently. They are to represent the legal standard for new construction in Germany by 2025 and will be attractively promoted until then. The number following the KfW represents the annual primary energy demand as a percentage of comparable new buildings. For example, a KfW40 house, which does not exceed 40% of the energy of the reference building. 



Germany-based IVG Energy Solutions GmbH, which focuses on providing energy solutions for households, has been helping households achieve KfW40+ houses recently. IVG understands occupant needs, including location, house size and roof type, and electricity usage, and determines the direction of implementation. Due to the shortage of electricity in Europe, many households have begun to install home photovoltaic energy storage systems. This time is no exception, with IVG opting to install residential energy storage for households.

During the peak electricity consumption period during the day, when the light is sufficient, the PV energy will be supplied to the load first, and the household load will consume the photovoltaic power generation to the greatest extent, and the remaining power will be stored by the battery; when the light is insufficient, the battery will supplement the power to the load.


During the low electricity consumption period at night, when the electricity price is low, the electric energy of the grid will charge and store the battery through the inverter charging and discharging controller. After the household load consumption is met and the battery is fully charged, the remaining power is fed to the grid. The important loads use electricity, then the battery is charged, and finally it flows to the household load, and the excess flows to the grid.

When the sunlight is insufficient or the electricity is used during the non-trough period at night, the battery sends electricity to the inverter through the DC control system, and is converted into AC power by the inverter for the use of the AC load.

The key link in the home energy storage system is the energy storage battery. IVG has found the energy storage battery expert Pytes Energy Co., Ltd. to provide it with energy storage batteries. This time, the batteries installed in KfW 40+ houses are exactly E-BOX-48100R batteries from Pytes.


The E-BOX-48100R is the new generation LFP battery for home energy storage system. The battery pack is compact, easy to install, free of maintenance, and could be deployed to the building block of energy storage system by being assembled in parallel. It is widely applied in home applications small commercial and industrial energy storage system as well as Telecom stations. E-BOX-48100R has a BMS to measure, monitor and manage solar panels and use the system in real time at all times. Moreover, it has a long service life and high safety, and is suitable for most inverters on the market, such as Victron, SMA, and Sol-Ark. In the above projects, the batteries facilitate the perfect matching of Deye inverters to provide sufficient power for the home. After the installation of the home energy storage system, if the residents have any problems, the service engineers from Pytes will patiently and exhaustively solve them for them.

Ultimately, Pytes helped IVG successfully realize three KfW40+ houses. Most houses are installed with 8KW/10KWh (inverter/battery), which is enough to meet the needs of most houses, and a few have installed 12KW/10KWh to meet higher power demands. And these houses not only meet the standard of KfW40+ house and save more energy, in addition, the owners will be subsidized by the national government, and get a grant of up to 45% of the qualified amount!


"We are very grateful to Pytes for their help with this project." IVG's CEO, Mr. Denis Röthke said, "We also look forward to working with Pytes to provide energy solutions to more households in the future, as well as to the possibilities of a clean energy source like solar in the energy market."

About IVG Energy Solutions GmbH

IVG Energy Solutions GmbH is your professional partner for planning and implementing a green future, providing distributors and solar installers with a package of solutions that will make you independent of your energy supplier. The founders Denis Röthke and Michael Giesa share a passion for new technological possibilities and over 40 years of experience as CEOs of tech companies.


About Pytes Energy Co., Ltd.

Pytes, formerly known as DLG, has been providing innovative clean energy solutions globally for decades. Its energy storage systems have been deployed in more than 40 countries and can be found in some of the most remote places on Earth. Pytes' systems are well known for their safety, reliability, competitive pricing and good services. We are praised by our customers for delivering all-in-one solutions, including lithium batteries, photovoltaic inverters, battery management systems, cloud monitoring, installation, maintenance and much more.