Three years after building the house, the family decided to implement the PV system that had originally already been planned. The primary focus was the desire for greater predictability—especially in view of the high electricity demand of the heat pump. 

The current discussions regarding changes to the feed-in tariff from 2027 onwards also provided the impetus to implement the project earlier than planned. Although a solar installation had been envisaged from the outset, there was initially no room for it in the budget immediately after construction. Since it was commissioned on 29 May 2026, the system has been generating its own solar power for the household and the heat pump – whilst also forming the flexible foundation for the future energy supply.
 

Optimal utilisation: 8.74 kWp across two roof areas

The PV system is installed on a hipped roof and utilises two optimally oriented areas:

• 14 PV modules on the large roof surface with a south-facing orientation of approximately 165°
• 5 PV modules on the smaller south-west-facing side
• 19 modules, each with 460 Wp (total installed capacity of 8.74 kWp)
• Approximately 38 m² of generator area with modules laid horizontally and without shading

These conditions provide the perfect basis for high yields: the projected annual output is around 9,184 kWh. This means that, on paper, the system generates significantly more energy than the family currently consumes.

KOSTAL PLENTICORE G3: The heart of the system

At the heart of the system is a KOSTAL PLENTICORE G3 M 8.5. It reliably converts solar power into usable alternating current and supplies it exactly where it is needed in the house.

The PLENTICORE is far more than a conventional solar inverter: depending on the system configuration, it can also be used flexibly as a hybrid or battery inverter. This is ideal for this system: at present, the solar power is consumed directly, but a battery storage unit is already firmly planned for the future. This allows the system to be adapted step by step to new requirements without having to replace the central unit.
 

Consciously shifting electricity consumption to sunny days

The family’s current electricity consumption stands at around 3,800 kWh per year (approximately 2,500 kWh for the heat pump and around 1,300 kWh for domestic use). The calculated self-consumption rate is 39.5 per cent.

To ensure that as much self-generated electricity as possible remains in the home, the family relies on simple everyday tricks: they prefer to do their washing during the day when the sun is shining, and the heat pump makes targeted use of peaks in generation to heat water. Even without a comprehensive smart-home control system, the project demonstrates just how effectively solar power can be utilised through conscious habits.

Ready for a battery storage system, wallbox and backup power

The system grows with its tasks. If a battery storage unit is retrofitted at a later date, surplus solar power can be stored and used in the evening. There are also plans to purchase an electric car and a wallbox in the future.

The KOSTAL PLENTICORE G3 offers the ideal conditions and great flexibility for this:

• Communication & integration: LAN, Wi-Fi, Modbus TCP, SG Ready and digital switching outputs simplify the connection of the heat pump and wallbox.
• Power expansion: The M power class simply scales up as demand increases.
• Multi Device Control (MDC): Enables centralised control of up to three PLENTICORE G3 inverters via a master unit in the event of future expansions.
• Back-up power option: When used in conjunction with a storage unit and a transfer switch, the PLENTICORE G3 also protects the home against mains power cuts.

Safety and future-proofing round off the package: an optional DC overvoltage protection device can be integrated, and the AutoUpdate function ensures the inverter is always running the latest software version.

Transparency via the KOSTAL Solar Portal & app access

With free monitoring via the KOSTAL Solar Portal and the KOSTAL Solar App, the family can keep track of all energy flows. Generation, consumption, self-consumption and self-sufficiency rates can be tracked in real time – this makes the energy transition tangible in your own home and helps you align your consumption even more closely with the yield curve.

A system that grows with the family

This reference installation demonstrates how to successfully make the transition to a modern energy supply: with a high-performance PV system, intelligent self-consumption and a flexible inverter at its heart. Today, the solar power supplies the household and the heat pump. Tomorrow, storage and a wallbox will follow. The KOSTAL PLENTICORE G3 M 8.5 provides the perfect, scalable foundation for this.