(Inverter) is required, and the electricity is consumed directly. So, for example, if you have a base load of approximately 10 kW/h from, say, 8:00 AM to 8:00 PM, a suitable solar system between 10 and 15 kW/h is exactly right for you. Without sun, however, no energy flows, and any excess energy generated is fed into the grid without storage and compensated accordingly, or, depending on your contract, stored for you. As you can see, there are various solutions and approaches. Energy recovery is somewhat more complex, but unlike solar energy, it works day and night. In classic energy recovery, it's not the electricity itself that is recovered, but rather the converted form of electricity. In the example of a sauna with 10 kW/h, a significant amount of electricity is converted into heat energy, which is slowly distributed throughout the sauna cabin.

As the number of sauna guests increases, air circulation is essential. This means fresh, cold air enters, which then needs to be heated, while the warm, used air is expelled from the building. This was standard practice not so long ago. However, with rising energy costs and advancements in technology, control options, and sensor technology, things are different today. Modern systems utilize the waste heat from the sauna, which would otherwise be lost outside, to preheat the fresh air directly in front of the sauna. This minimizes the energy required by the sauna heater and brings the room to the desired temperature. For example, the incoming air temperature can be 40-50°C instead of 20°C, and the temperature difference the sauna heater needs to overcome is only 30-40°C instead of 60°C to reach an 80°C setting. As a result, the hourly energy consumption of 10 kWh is reduced to a potential energy requirement of only 6-8 kWh. In combination with a solar power system, it is therefore possible that you will not need any additional energy from the energy supplier even if the sun is not shining brightly.