Power grids need perfect balance between source and consumer. Balancing energy is needed to compensate deviations between generation and consumption of electrical energy


  • ELWA power-to-heat systems fulfil the the requirements to be used for minute reserve or secondary reserve.
  • ELWA power-to-heat systems operate step-less and are designed for frequent cutting off (there is no minimum ON time)
  • Existing combined heat and power stations and ELWA power-to-heat systems ca be operated „in tandem“ to offer perfect balancing energy and process heat.
  • ELWA power-to-heat system can be operated aside of the energy balance market to make use of energy peaks – e.g if the grid provider would shut down the customers wind turbine (feed-in management), the turbine can be kept in operation to generate heat.

ELWA power-to-heat system provide flexible negative balancing energy, preferably connected to district heating systems because of the permanent high demand for thermal energy.

Advantages of power-to-heat

  • High revenues from the balancing energy market
  • Low maintenance cost – reduced TCO
  • Simple repowering for higher efficiency and flexibility
  • Combined power stations & P2H: optimised operational range

System description

Construction of ELWA Power-to-Heat system

District heating: Avoid shutting down wind turbines or solar power stations in case of grid overload. Booster heater for remote branches of the district heating network

Combined power & heat stations: Optimisation of operation point. Avoidance of part load operation. Preheating to reduce maintenance and to keep system inside emission limits (TA Luft)

Large heat pumps: Peak load support and emergency heating. Optimised annual performance factors

Legionella: Thermal disinfection of potable water

Process heat for renewable energy systems: up to 200°C booster heating. Precise heat control for unstable biogenic heat sources )e.g. wood chip burners)

Biogas systems: Upgrade of base-load systems for peak-load operation: step-less & precise control of process heat

Wood-drying: Transfer of photovoltaic energy into heat buffer tanks

Absorption-type refrigeration systems / large thermal buffer systems / geothermal buffer systems / ice buffer systems: Charging with excess photovoltaic energy.

Grid support: grid stabilising, peak wave and peak voltage reduction, peak shave, balancing of asymmetric load, „grid hovering“, variable counter-load for frequency stabilisation, support during “black start”

The ELWA P2H system has been developed to combine operational safety, high availability and ease of maintenance. The system consists of at least one and up to an unlimited number of units from < 100 kW up to 1.68 MW heating power. The system is modular, scalable and redundant. It offers unique advantages compared to large monolithic systems. Possible blackouts of subsystems can be immediately compensated by hot spares. Subsystems can be taken out of service for maintenance without losing the complete heating power. All parts can be exchanges with standard tools. The necessary space for installation is not larger or even less than for monolithic systems.

The systems are installed for parallel operation with bypass piping. Required installation work on customers side: Piping to/from the unit and main supply cable. The ELWA P2H control cabinet with its user-friendly 8.4” control display can control an unlimited number of subsystems.

ELWA has always ben active in fields were high availability is paramount.

System infinitely expandible

Less space and less cost compared to vulnerable large single unit systems

Easy maintenance: subsystems can be taken out of the system and all parts can be replaced with standard tools (even single heating elements) = low TCO

Reduced downtimes

Avoids loss of complete power

Hot-standby possible: spare unit kicks in in case of problem with a subsystem

8,5“ color display in main control cabinet (daughter displays available)

Failure reporting system with history recording

Protected data logging system / line recorder

Fieldbus interface to main control system (Profi bus/Modbus TCP/Modbus RTU)

Stepless power control possible

True power control with secondary temperature control for the heating medium circuit

Temperature monitoring

ELWA Steuerung Leitschrank

Safety system according to DIN EN 12828

Low level protection

Pressure monitoring

Temperature safety cutout STB (110°C) / TW (100°C)

Flow monitoring

Performance data





















Design pressure

10 bar

higher pressures on request

Design temperature


higher temperatures on request

Operating voltage

400 Vac

400/690 Vac, other voltages on request