[Mainland China] "Wastewater Plant + Photovoltaics" Completes One Year of Operation: Two Plants in Ezhou Generate 1.94 Million kWh Annually, with a Self-Consumption Rate of 78%

Key Highlights: The Gehua Wastewater Treatment Plant and Honglianhu Wastewater Treatment Plant of Ezhou Water Group in Hubei Province have operated for one year under the "self-generation for self-consumption, surplus power to grid" model, with total power generation of 194万 kWh, of which 151万 kWh was self-consumed, average monthly self-consumption rate reaching 78%, and annual carbon dioxide reduction exceeding 1530 tons. The photovoltaic panels above the tanks also inhibited algae growth, indirectly reducing chemical dosage.

I. One-Year Report Card: Generation, Self-Consumption, and Grid Feed-In

According to the New Energy Business Division of Ezhou Water Group, from 2024年 9月 to 2025年 9月, the photovoltaic projects at the two wastewater treatment plants delivered the following results:

• Total power generation of 194万 kWh — clean electricity directly fed into the plant's power consumption system
• On-site self-consumption of 151万 kWh — covering part of the high-energy-consuming processes such as aeration, lifting, and chemical dosing
• Surplus power to grid of 43万 kWh — electricity sales revenue reaching over 20 ten thousand yuan
• Average monthly self-consumption rate of 78% — good matching between generation curve and consumption curve
• Total revenue of over 100 ten thousand yuan — energy savings and revenue generation combined

The two wastewater treatment plants have a total treatment capacity of 10万 tons per day, serving an area of 200 square kilometers. The photovoltaic project fully utilized the idle space above the clear water tanks and on plant rooftops, with a total of 2669 photovoltaic modules installed.

II. An "Unexpected Benefit": Photovoltaic Panels Also Keep Algae in Check

The clear water tanks and sedimentation tanks of wastewater treatment plants are exposed to sunlight for extended periods, making algae growth a common challenge that often requires additional chemical dosing for control. The photovoltaic panels installed above the tanks form a natural shading layer, effectively inhibiting algae growth in the tanks and directly reducing the dosage of related water treatment chemicals.

This means the value of "wastewater plant + photovoltaic" goes beyond power generation revenue — it simultaneously improves process operating conditions, achieving a win-win of energy savings and process optimization. This is a synergistic effect that a standalone rooftop photovoltaic project cannot replicate.

III. Why Wastewater Treatment Plants Are Suitable for Photovoltaic Installation

First, ample plant space. There is a large amount of underutilized space above tanks, on plant rooftops, and inside and outside perimeter walls, without occupying additional land resources.

Second, stable and continuous power load. Wastewater plants operate 24小时, with equipment such as aeration and lifting pumps forming a stable base load, resulting in a high self-consumption ratio — in sharp contrast to the mismatch problem of commercial and industrial rooftop photovoltaics where "power is generated during the day but less is used on weekends."

Third, low-carbon indicators have entered the assessment system. Under stricter discharge standards and "dual carbon" requirements, indicators such as the self-supply rate of distributed photovoltaics in plant areas are being incorporated into environmental credit evaluation dimensions. Photovoltaics is no longer an optional item, but a necessary choice with clear returns.

IV. The Bigger Picture: From "Energy Consumer" to "Energy Producer"

Wastewater treatment is a typical high-energy-consuming industry, with the aeration process typically accounting for over 50% of the plant's total electricity consumption. Against the backdrop of continuously rising electricity costs and increasingly stringent low-carbon assessments, "on-site self-generation" has become one of the most realistic cost-reduction paths for existing water plants. The practice in Ezhou demonstrates that as long as spatial resources, load characteristics, and generation curves are well matched, wastewater treatment plants can completely transform from pure energy consumers to partial energy producers, thereby leveraging overall optimization of the operation and maintenance cost structure.

V. Three Recommendations for Existing Water Plants

• First, calculate the load account — compile the plant's hourly electricity consumption curve, match the photovoltaic installation scale, and avoid curtailment
• Second, select installation surfaces — above-tank installations must account for structural safety and maintenance access; materials should be corrosion-resistant and wind-pressure resistant
• Finally, build a revenue model — combine power generation revenue, chemical savings, and carbon asset revenue into a consolidated calculation to reflect true investment returns

When wastewater treatment plants shift from "energy consumption giants" to "energy production units," green and low-carbon is no longer just a social responsibility, but a quantifiable business account.

About TIANYI TECH

TIANYI LIMITED (Hong Kong) focuses on industrial water treatment and water resource reuse. Centered on three core products — Industrial Wastewater Treatment AI Agent, Industrial Water Reuse Optimization System, and Industrial Water System Digital Twin — it helps enterprises achieve stable compliance, energy saving and consumption reduction, and water resource recycling in a data-driven manner.

Contact us: +852 66162262 | info@tianyitech.hk