KOSTAL Pressebereich
Freiburg, 21/04/2023

Inverter and heat pump: KOSTAL and Solvis are driving the energy transition forward together

Together, KOSTAL and Solvis have set themselves the goal of bringing an intelligent combination of inverters with heat pumps and PV2Heat systems to the market. This makes efficient use of heating stratified charge buffer storage as additional energy storage if there is a PV surplus. This increases the self-consumption proportion of the self-generated PV electricity, boosting the cost-effectiveness of the PV system and the degree of self-sufficiency.

The most important facts in a nutshell

- A buffer storage unit with connected electric heat generator provides the energy needed to boost heating
- Two PLENTICORE plus enable up to five roof alignments with battery storage units
- This ensures as much self-produced PV electricity as possible, even during periods when there is little sunshine
- SG-Ready (from PLENTICORE plus G2) enables intelligent control via Modbus TCP so that the heat pump uses the buffer storage if there is a PV surplus

Smart combination of inverter and heat pump

Energy storage is a basic prerequisite for sector coupling. With patented stratified charge buffer storage, Solvis offers a solution for storing energy in a thermally efficient way. For example, a SolvisMax buffer storage unit with a nominal volume of 750 l can store approx. 8.6 kWh of thermal energy with a water heating system of just 10 °K.

Especially in view of current climate targets, this is of great importance, because space heating and hot water consume about 30% of final energy in Germany. More than 70% of this final energy is currently covered by fossil fuels. Sector coupling between KOSTAL and Solvis is driving forward the energy revolution and, above all, the heating revolution and helping to reduce CO2 emissions. Using a heat pump in combination with a photovoltaic system and intelligent controller can save over 75 % of a single-family house's CO2 emissions per year.

Heat pump and inverter working together

Sector coupling is achieved on a technical level by linking the system controllers from Solvis and KOSTAL. The PLENTICORE converts the direct current of the PV modules into alternating current, which can be consumed in the house grid. The remaining PV power is stored in the battery system, if one is available.

Advantage of the KOSTAL and Solvis system

The heat pump uses the surplus power that would otherwise be fed into the public grid. The heat pump controller retrieves information about the excess power via the network and ensures that no more than the available power is ever consumed by the HP. This is a clear advantage over the SG Ready interface, where only imprecise control is possible. In combination with SG Ready, the HP may even draw power from the grid. Therefore, more electricity is saved with network-based control.

The SolvisControl 3 (SC-3 for short) is the central controller of the Solvis hybrid heating systems. It can be used to operate various heat generators, such as the heat pump, thermal solar systems, conventional heat generators, a pellet heating system, PV2Heat systems and/or an external heat generator.

The SC-3 displays all system parameters, energy balances, the operational status and sensor values from the heating system as well as the system diagrams with values in real time. These values can be viewed free of charge via the Solvis portal and are available to the system operators and specialist engineers providing support.

Both systems can be easily linked with each other via Modbus TCP. This link can be established between the Solvis Control and a KOSTAL Smart Energy Meter or a PLENTICORE inverter. The recorded PV surplus is used in a modulating manner with a heat pump or PV2Heat system, taking into account the property and buffer storage temperature.

Why is photovoltaics with a heat pump worthwhile?

This sector coupling is indispensable for innovations in heat supply. The federal government calculates that 500,000 new heat pumps will be installed each year from 2024. And from January 2024, as far as possible, every new heating system installed and replaced is to be powered 65 percent by renewable energy. This makes clear the importance of sector coupling between photovoltaics and heat pumps for ensuring a reliable power supply.


Energy from your own roof is the cheapest and most sustainable way to meet your own power requirement. Intelligent control and optimum interaction of all system components increases the degree of self-use. 

About Solvis

For more than 40 years, Solvis GmbH from Braunschweig has been the birthplace of heating using hybrid energy sources. The medium-sized heating manufacturer is driving forward innovation and is one of the leading technology providers for heating systems in Europe. Solvis distinguishes itself through particularly efficient, modular, flexible and future-oriented heating technologies. 

About KOSTAL Solar Electric

KOSTAL Solar Electric was founded in 2006 as a separate branch of KOSTAL Industrie Elektrik. Today, KOSTAL Solar Electric is one of the leading suppliers of innovative solar, hybrid and battery inverters – for domestic and commercial systems. The KOSTAL Smart Energy Meter and the KOSTAL wallbox round off the innovative product portfolio. With KOSTAL products and the KOSTAL Solar Portal and KOSTAL Solar App monitoring tools, KOSTAL customers have key instruments for intelligently generating, storing, controlling and using solar power.