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A joint project by dena and Tilia

Since 2015, Tilia GmbH has been supporting Vietnamese municipal waste water companies when it comes to optimising their operations, particularly with regards to improving performance and energy efficiency. As part of a develoPPP project (“Good practices and the development of a management partnership for optimised operational waste water management in Vietnam”) supported by GIZ [German Federal Enterprise for International Cooperation], a close cooperation has been developed with the waste water company for the provincial Vietnamese town of Sóc Trăng. 

PV system with 30kWp powers sewage treatment plant


One idea, which was developed together with our Vietnamese partner, was the concept of covering the energy needs of Sóc Trăng’s sewage treatment plant through renewable sources. Upon considering various approaches, the use of PV electricity presented itself as a solution which made sense both economically and ecologically. The concept idea was transferred to the implementation stage with the acceptance of the project into the German Energy Agency (dena)’s “Renewable Energy Solutions Programme”. 




For this reason, Tilia GmbH and the operator of the municipal waste water infrastructure facilities, the Sóc Trăng Public Works Company (SPWC), decided to pursue this idea after the develoPPP project had been concluded. They were able to find support in the form of dena, the German Energy Agency, which enabled them to turn the joint project from an idea into reality. 




After evaluating various possibilities with regards to dimensions and system configurations, an optimal solution regarding size and demand profile was able to be determined: the generation of renewable electricity takes place via a photovoltaic system with an output of 30kWp, installed on the roof surfaces of the sewage treatment plant’s drying beds. What’s more, an innovative storage solution also forms part of the system. This enables energy, which is not needed, directly to be stored in the meantime and used at a later point in time.



Sóc Trăng, Vietnam

Sóc Trăng



What we achieved












Key Technical Data








Flexibility enables efficiency

The high level of flexibility of the volume of electricity purchased by the sewage treatment plant enables the plant to be operated with the maximum amount of stored electricity during those times with the highest electricity purchase costs (daily peak periods during the morning and evening). This is an aspect which has a positive effect when it comes to cost savings and efficiency. In total, a storage capacity of 20 kWh is available.









Installing the system




Training courses





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