openWB controls AC•THOR 9s

The renovated semi-detached house is in Lower Saxony, the customer is a hobbyist and has been looking for a way to change his heating system on his own. With the 19.98 kWp photovoltaic system distributed over various roof surfaces, the four-person household on the 135 m² living space has enough yield from the photovoltaic system to use some of it for space heating.

A classic heat pump system for the well-insulated house seemed unsuitable because it is oversized due to the high costs for the heat pump system. The previous heating system is only used during the heating period, and even here the energy requirement has been very low so far with the existing gas boiler at 6,000 kWh per year. A heat pump would not have been economical even with funding.

After a little research on the internet, the customer found our 9 kW immersion heater in combination with the linearly controlled photovoltaic power manager AC•THOR 9s.

The installation was made easy with the minimal overall costs that are only a tenth compared to the heat pump, as the existing buffer storage with 700 l offers sufficient storage capacity for the excess power from the photovoltaic system.

Combined with openWB for the first time

The solutions from my-PV were installed in October 2021, just in time for the start of the heating season, and have been supplying the house with hot water and space heating ever since. It was important to the customer that the new solution could be integrated into the existing energy management system. The energy flows are controlled with a Raspberry Pi on which the EMS from openWB is installed. This way, AC•THOR 9s can also be controlled.

The first operating experiences are very promising: calculated over the year, 3,200 kWh can be expected for hot water and space heating. In terms of energy, this is almost half the consumption of the previously installed gas boiler!

"The devices and solutions from my-PV have been working very reliably for four and a half months. The integration of the control system into openWB's own EMS was decisive for me and runs absolutely satisfactorily," the customer from Lower Saxony summarizes, with satisfaction about the new solution with our products.

Why the battery storage is ranked second place

Since the energy requirement for hot water and space heating is not insignificant in the winter months, the use of BYD's battery storage makes no sense for the customer during this time. For this reason, the following priority has been set for the surplus from the photovoltaic system:

First, connected electric vehicles (2 electric cars in the household), then the heating system from my-PV and only then the battery storage. The my-PV system turns the buffer storage into an energy storage during winter operation – the battery storage is thus protected and then comes into use with the higher yields in the warmer months.

To the reference project