System solution for car wash facilities: Process optimisation and solar thermal energy for Clean Line in Ratingen

Car washes are especially crowded on sunny days. The company Clean Line GmbH in Ratingen has optimised its facility for this very reason, with the help of a sophisticated system solution that directly utilises energy from the Sun while at the same time increasing efficiency of the washing process. The solution called Hotdrop increases not only the profitability of the car wash, but also makes an important contribution to climate protection.

In addition to the actual washing water, the washing space and the entrance and exit at a car wash must be heated so that they do not freeze during low outdoor temperatures. In most cases, the combustion of fossil sources of energy provides the required heating amount to operate the washing facility. With the help of the Hotdrop system solution, the company bearing the same name will make the required heat for the facility in Ratingen available using up to 23 per cent renewable energy sources. Additionally, the entire washing process is monitored and optimised by the new control software, increasing the efficiency of the entire facility by 22 per cent.

Engine for progress:

“Especially at Clean Line Car Wash, the Hotdrop system solution not only increases the reliability of operation in terms of heat management, but also significantly contributes to climate protection since the system significantly reduces CO2 emissions. The integration of solar thermal energy and the optimisation of the process heat leads to a lucrative increase in profitability.”

Ingo Zehnpfenning, Hotdrop Project Manager

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The Ratingen Clean Line Car Wash is one of the largest solar thermal energy-powered car washes in all of Germany.

Savings through solar thermal energy and process monitoring

During the course of the modification with Hotdrop, a total of 51 solar thermal collectors with a power supply of 83 kilowatts were installed on the roof of the Clean Line car wash. This makes it one of the largest solar-powered car washes in Germany. The solar collectors used to heat the water provide approximately 55,000 kilowatt-hours of heating per year, thereby saving fossil energy. An additional important contribution to climate protection is that Hotdrop provides a specially developed control and monitoring software that is installed by the manufacturer. The software displays detailed information on the washing process and all the relevant heat quantities. The generated data is evaluated with a view to optimising the heat supply and heat use by means of the software. With the help of these measures, the Rantinger car wash now saves around 94,000 kilowatt-hours of heat and 40 per cent of the allocated fossil energy. The achieved increase in efficiency and use of solar thermal energy save a total CO2 quantity of around 12.7 tonnes per year. This savings corresponds to the amount of CO2 absorbed by approximately 1,016 trees.

Hotdrop system solution is transferable

In addition to the car washing and care centre in Ratingen, seven more facilities have been equipped with the Hotdrop system solution in North Rhine-Westphalia (NRW) that together ensure a total savings of 72.3 tonnes of CO2 per year. This amount of CO2 is equivalent to the amount that a 5.5-hectare German forest could absorb.


  • Use of solar energy when available
  • Process cost optimisation through increased efficiency
  • Combination of climate protection and increased profitability

Partners and sponsors

  • Dachdeckermeisterbetrieb Julian Dauber
  • Heizungsbaumeister Hamulczyk
  • Zürner technologies GmbH
  • ems-ing Statik Dipl.-Ing. Peter Steffen

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