Photon Energy Case Study

Tailor-made Solutions for a Wastewater Treatment Plant

Koszalin, Poland

A unique application of solar technology to increase energy security and mitigate environmental impacts.


Miejskie Wodociągi i Kanalizacja Sp. z o. o. w Koszalinin


September 2021

Key Numbers

950 kWp


Up to 860 MWh

Annual Production

Up to 560  t

Avoided CO2 Annually

The Challenge

With extremely high energy demands, the water supply and wastewater treatment plant (WWTP) in the Polish city of Koszalin was looking for a new, cost-effective source of clean, reliable power.

When launched in 1995, the Koszalin plant was one of the country’s best automated and equipped mechanical-biological treatment plants with chemically supported treatment processes. The plant has a total capacity of 36,000 m3 per day and serves Koszalin as well as neighboring cities. Located in northern Poland, Koszalin is close to both the Baltic Sea and Jamno, a brackish coastal lagoon divided from the sea by a spit, now a popular place for sailing.

Miejskie Wodociągi i Kanalizacja Sp. z o.o., the organisation responsible for the care, control and management of the WWTP, decided to invest in its own renewable energy source. Its aims were to increase its energy independence, reduce energy costs and mitigate the environmental impact of its activities.

The Solution

As part of a consortium led by RenCraft, Photon Energy designed, developed and installed a PV power plant at the Koszalin WWTP.

The power plant offers a unique solution: 2880 PV panels arranged in a somewhat uncommon east-west orientation that ensures even power generation throughout the day, without the usual steep midday peaks.

The installation is equipped with an automated power distribution station, which allows the electricity generated to be used according to the demands of each of the WWTP’s two mid-voltage receiving sections. From a technical point of view, the system also enables participation in demand side response (DSR) or other forms of intelligent power supply management.

The power plant works under the net-zero export regime, which requires the electricity generated to be consumed on-site, with limited means of supplying surplus energy to the grid. A tailor-made power generation management system optimises auto-consumption within given safety limits.

Representing Photon Energy’s fourth collaboration with RenCraft, this project was successfully realised at the height of the COVID-19 pandemic, and was commissioned in September 2021.

The estimated total annual generation capability of the installation is 860 MWh. This reliable supply of clean energy and the future-proof nature of our solution – which makes further updates to the system straightforward and cost-effective – provides significant energy security at a time when electricity prices are rising around the world.

Contact us now to learn more about our work.

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