It is proposed to deploy overhead floating photovoltaic systems for Mussum Sewage Treatment Plant in Bocholt, Westphalin, Germany, directly covering the existing aeration tank and other water treatment structures, without additional land occupation. The objective is to reduce the operating electricity cost and carbon emission, and to comply with the mandatory requirements for energy production of large sewage treatment plants in the new EU Municipal Sewage Directive. The proposal was formally submitted by a municipal council party group and the results of the feasibility study will be considered by the Bohort Municipal Utilities Company (ESB) Operating Committee on 18 June 2026.
Sewage treatment is a typical high energy consumption infrastructure-pumping stations, blowers, aeration systems require 24 hours of continuous operation, and electricity costs account for 30%-50% of total operational expenditures throughout the year. The Musum Sewage Treatment Plant in Boholt is no exception. The proposal focuses on "space reuse": erect a support structure on the hardened tank surface and install PV modules to avoid land acquisition and conflict between ground PV and plant operation and maintenance line. The technical path refers to the "Solarfaltdach" scheme put into operation - the system adopts light aluminum alloy support+ double glass components, with a span of more than 15m, taking into account the light transmittance and sunlight and algae control functions, and allows daily hoisting equipment access and manual inspection of the pool surface.
The proposal explicitly calls for an economic threshold: payback period of no more than 7 years, i.e. the savings over the full life cycle must cover all the initial inputs. Referring to the case of Dusseldorf, the actual payback period of the floating PV system of the same structure is 5 to 6 years, mainly because the local industrial electricity price (about 0.28 euro/kwh) is significantly higher than the average value in Germany, and the spontaneous self-use rate of the plant area is close to 100%-the generated energy is directly used by the blower, dosing pump and other loads, and almost no on-grid settlement loss is generated. The Boholt Project has not disclosed specific installed capacity and investment, but the feasibility study will synchronously evaluate subsidy policies at Federal, Nordic and European Union levels, including KFW Bank Low-Interest Loan, European Recovery Fund (RRF) Green Infrastructure Project and supporting funds for municipal energy transformation in the "Climate Protection Plan 2030".
Downstream Application Link: Distributed Energy Transformation of Municipal Water Facilities
The project is in the operation of environmental infrastructure and not upstream of equipment manufacturing or EPC. Its core value is to verify the adaptability of "water plant roof photovoltaic" mode in small and medium-sized municipal projects - different from large ground power stations, such projects put forward differentiated requirements for module corrosion resistance (HS, NHgas environment), support anti-corrosion grade (required to meet C5-M marine industry standard), operation and maintenance channel reservation (crane operation radius, safety barrier height). If a similar scheme is considered to be introduced to similar sewage treatment plants in China, the following three points shall be paid attention to: first, measured PID attenuation rate data of German double glass module under high humidity and sour environment (generally, the attenuation in 10 years shall be ≤ 10%). Secondly, whether the support system has passed TV Rheinland wind load and snow load joint certification (especially applicable to the rainy areas in East China and South China). Third, whether the inverter supports 100% off-grid black start mode to ensure the power supply continuity of key process units in case of power failure.
Supply Chain Concerns: German Content Integration and Certification Barriers
The path of "local design+ local construction" is adopted for the Boholt Project. Photovoltaic modules are generally purchased from German local brands (such as Century and Meyer Burger) or European production line products, while the support system is preferably from German Schletter, K2 Systems and other professional manufacturers. For Chinese PV enterprises, this type of municipal project is not a direct export opportunity, but a window to observe the technical preferences of the German market segment: its bidding documents generally force CE-EN 50583-1 (integrated electrical safety of PV buildings), DIN SPEC 4102-4 (fire rating B-s1, d0) and VDE-AR-E 2100-712 (special grounding specifications for sewage treatment scenarios). It is worth noting that, in recent years, the "green premium on market purchase" mechanism has been promoted in Northern Wei State - under the same conditions, the product with EPD environmental product statement and ISO 14040 life cycle assessment report can obtain the highest 5% price bonus, which has a clear direction for China Head Component Factory to promote LCA certification.
The new EU Municipal Wastewater Directive (Revised 2024) has set a phased objective: from 2027, sewage treatment plants with a daily treatment capacity of over 100,000 tons must achieve at least 15% energy self-sufficiency. Rise to 30% by 2030. Boholt does not meet this threshold, but early placement can avoid future compliance risks. For the export-oriented enterprises in China, this means that the municipal water upgrading demand in Germany and surrounding countries will shift from "optional energy conservation" to "rigid compliance", and the localization and adaptability of relevant PV supports, anti-fouling coating components and intelligent monitoring systems will become the key fulcrum to pry orders.
