Hot water preparation using surplus PV power – without fossil fuels
Do you have a photovoltaic system and want to use your self-generated electricity even more efficiently? The my-PV 9 kW screw-in heating element converts excess solar power into hot water. This works in both fresh water storage tanks and buffer tanks for your heating system.
Unlike feeding electricity into the grid, which now only receives minimal compensation, you use your PV electricity directly on site. This increases your self-consumption and simultaneously reduces the costs of gas or oil for hot water preparation.
The heating element works exclusively with the my-PV AC THOR 9s power manager. This power manager continuously measures the available surplus energy from your PV system and continuously adjusts the heating output between 0 and 9.000 watts. This ensures no energy is wasted.
Why the my-PV 9 kW screw-in radiator is the right choice
Stepless adjustment to your PV yield
Conventional heating elements often operate at fixed power levels. In contrast, the my-PV screw-in heating element is regulated by the AC THOR 9s with second-by-second precision. For example, if your PV system is generating 4.500 watts of excess power, the heating element operates at precisely this output. If the excess drops to 2.000 watts, the heating power adjusts automatically. This avoids drawing power from the grid and maximizes the use of your solar energy.
Also suitable for large storage capacities
With a power output of 9.000 watts, the heating element can efficiently charge even larger buffer storage tanks. For example, a 1.000-liter tank can be heated in approximately 5 to 6 hours at full power and a temperature difference of 40 degrees Celsius. With larger PV systems that regularly generate excess power, this is easily achievable on many days from spring to autumn.
The AC THOR 9s can control up to three heating elements sequentially. This allows you to combine multiple screw-in heating elements to charge large storage tanks faster or to supply different storage tanks separately.
Designed for long service life
The heating elements in the screw-in heating element are designed to keep the thermal surface load low. This reduces material wear and extends the heating element's lifespan. However, for water hardness levels above 7 °dH, the manufacturer recommends regular maintenance or the use of a water softener, as limescale deposits can impair efficiency. Damage caused by limescale is excluded from the warranty.
This is how the 9 kW screw-in heating element works in practice.
Installation in existing storage
The heating element has a 1 1/2 inch thread, which is standard on most hot water and buffer storage tanks. It is installed horizontally. You need a clearance of the installation length plus 150 mm in front of the mounting flange for installation and maintenance. The unheated zone is 130 mm from the sealing surface – ensure your storage tank flange is not longer than this.
The connection is made via a three-phase power supply (3 x 230 V). The connection cable is fed into the connection compartment of the heating element using the supplied cable gland. Ensure the cable is adequately sized and be sure to connect the protective earth conductor.
Temperature control in everyday life
You can set a target temperature between 34 and 78 °C using the rotary knob on the heating element itself. Once this temperature is reached, the integrated bimetallic thermostat switches off. The AC THOR 9s detects this shutdown and switches to standby mode.
Technical details and application possibilities
What can you do with the 9 kW screw-in heating element?
The heating element is suitable for various applications:
- Hot water preparation in a single-family homeEspecially from spring to autumn, the hot water demand can often be completely covered by excess PV power.
- Buffer storage tanks for heating systemsYou can temporarily store excess solar energy in your buffer storage tank and use it later for space heating.
- Support for existing heating systemsDuring the transitional seasons, the heating element relieves the strain on your gas or oil heating system. On sunny days, the fossil fuel burner remains off.
- Combination with solar thermal energyIf you already have a solar thermal system, the heating element can serve as a supplement when the sun is insufficient.
Recommended accessories:
- my-PV AC THOR 9s Power Manager (absolutely essential for operation)
- my-PV temperature sensor (additional sensors for precise temperature measurement)
System openness and integration
The AC THOR 9s, which controls the heating element, can communicate with various energy management systems. The system can be integrated into smart home solutions via RJ45 or RS485. Visualization within the energy management system is also possible.
The AC THOR 9s also works with compatible battery storage systems. You can set the priority between battery storage and thermal storage. For example, you can charge the battery first and only then use the remaining excess energy for hot water – or vice versa.



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