Basics (FAQ)

Basic information for planning CHP projects

CHP units (Combined Heat and Power generation units) use the cogeneration principle to produce heat and electricity at once: Efficient, decentral on site and without transportation losses. In contrast to large power plants, they can be switched on and off and regulated in partial load within seconds. Also this possiblity to provide electricity within seconds makes them increasingly important in the energy future to balance out the fluctuations of wind and solar power.

Their clean, efficienct and flexibile generation of heat and power is an important reason why the German government aims at increasing the share of cogeneration in the power mix in the 2016 version of the law on cogeneration (KWKG).

Auslegung nach Wärmebedarf engTo ensure a high utilization rate over the year, CHP units are mostly sized by the heat baseload of an object (e.g. hotel). This way they cover are large part of the energy consumption, often more than half of the heat and power needed over the year. Peaks of the power demand are covered by the public mains – and peak boilers provide the heat demand not covered by the CHP unit on especially cold days.

To define the appropriat CHP plant size the maximum heat load (Qmax) on the coldest day is used. Depending on climate zone, object type and power / gas prices, a profitable operation can be reached if the thermal power of the CHP unit (QCHP) is ca. 10 – 30% of Qmax.

In special cases, e.g. to provide emergency power for defined consumers or to fully supply objects with power in island operation, the CHP unit is sized by the electricity demand.

Multiple CHP unit schemes
With our individually configurable superordinate control MaxiManager several CHP units can be combined and controlled together with boilers and heat storages.

These multiple CHP unit schemes allow a more precise adaption to the heat demand of the object – and an energy supply with compact CHP units in the Megawatt power range. Their redundancy also increases the availability of the CHP scheme because during the maintenance works of one CHP unit the other CHP unit(s) can still operate.

Auslegungstabelle engSizing table
This table offers a first indication for the correct sizing. We are happy to discuss with you which size would be best for your specific CHP project. Further information can be found in our sizing principles.

CHP units generate their profitability from the efficent use of fuel to create heat and power. The lower the fuel cost (e.g. for natural gas) and the higher the electricity and heat cost, the higher is the profitability of the CHP project. If the amount of heat the CHP unit generates is not needed for most of the year, the CHP unit is not profitable – except if electricity is extremely expensive or/and unreliable and the fuel very cheap.

The governmental policies towards decentral cogeneration, of course, also play a role. We can only assess the public support in Germany, which has improved especially since the introduction of the cogeneration law in 2002 and its updates in 2009, 2012 and 2016.

The major savings factors for CHP projects are:

  • reduced electricity bill
  • reduced fuel costs for heating
  • evtl. saving of an emergency power unit
  • evtl. electricity sale revenues to third parties
  • evtl. feed-in tariffs, tax breaks, cogeneration bonus or other public support

The major cost factors are:

  • CHP scheme investment
  • fuel costs
  • maintenance cost (X EUR/operation hour)

SOKRATHERM can offer servicing in Germany and help find a servicing partner especially in Poland, Russia, Italy, Slovenia, Ireland and Chile. Please contact the partners directly for an inquiry and our sales headquarters in Hiddenhausen for other countries.

Our compact CHP units are constructed for least possible space requirement in the heating room. Since they have to be serviced regularly (every 1000-1500 h), certain minimum distances to other objects must be kept. These are from the smallest CHP class to the biggest:

  • to the front: 1500 (50 kW class) to 2000 mm (500 kW class) since the exhaust heat exchanger must be removed to the front for cleaning.
  • to the rear: 600 – 1500 mm
  • sideways: 1000 – 1750 mm
  • upwards at certain spots 700 mm from the upper edge

This sketch of an example heating room with a CHP unit of the 100 kW class and boiler is, as well as the connection and dimensions diagram of the CHP units, available for download in the password protected planner’s area.

If the space situation is challenging in your CHP project feel free to contact us ideally with a sketch of the current heating room situation. We will be happy to check with you if we can find a solution together.


Service and maintance for CHP units

Integral part of the SOKRATHERM product range are proven maintenance concepts continuously adapted to the technological progress.



CHP unit service

For each CHP project we offer individual service packages – from simple regular maintenance up to the ›carefree package‹ with operation optimization.



Customer care

Our aim is to achieve together with our customer the best profitability, lifetime, reliability and emissions reduction from the CHP projects.



Brochures and planning documents

The download area provides our delivery charts, borchures and other planning documents.


The company

Powered by tradition

For over 40 years we find our drive in climate protection and continuously improve the energy efficiency and performance of our products.


Compact CHP units

Our cogeneration units over 50 kW

With their ability to provide and regulate power within seconds CHP units units are the perfect partner of fluctuating renewable energy sources.


Kachel SOKRATHERM Referenzen


Reference examples

Whether in hotels, factories, hospitals, industrial sites or water purification plants - our compact CHP units prove efficient and reliable operation in all kinds of objects.


Locations and partners

We're there for you

Contact data to international sales locations and company sites in Germany.