Solar Hot Water Project of Xi'an University of Technology

Driven by China’s "dual carbon" goals (carbon peaking by 2030, carbon neutrality by 2060) and green campus development, universities—key for energy consumption and environmental education—are exploring renewable energy applications. Xi'an University of Technology, leveraging Shaanxi’s abundant solar resources and addressing (teachers and students) hot water needs, launched a 10-ton/day solar hot water project. This initiative provides stable, clean energy for campus life, embodies low-carbon concepts, and offers a replicable model for university energy transformation.

I. Project Background: Demand and Responsibility

As a comprehensive university with tens of thousands of (teachers and students)，Xi'an University of Technology had massive daily hot water demand. Previously, it relied on traditional gas-fired boilers and electric heaters—high in energy use, costs, carbon emissions, and maintenance. With rising living quality demands and stricter national green university standards, the old system failed to meet "energy-saving, eco-friendly, efficient" goals.

Xi'an, Shaanxi, has rich solar resources: 2,000-2,600 annual sunshine hours and 4,500-5,000 MJ/㎡ annual solar radiation. This enabled the university to use the solar project to transform its energy structure—solving "hot water access and cost issues" while fulfilling environmental responsibilities and boosting green campus development.

II. Technical Solution: 10-Ton/Day Design

To balance demand and efficiency, the university partnered with solar firms to create a customized 10-ton/day system, focusing on "heat collection, storage, and auxiliary heating."

Heat Collection: 120 ㎡ high-efficiency flat-plate collectors were installed on dorm and teaching building rooftops. Using high-absorption coatings, they maintain over 60% efficiency even in Xi'an’s winter, ensuring basic heat on cloudy days. Connected in series, they convert solar energy to heat, transferred to storage tanks via antifreeze.

Heat Storage: Two 5-ton insulated tanks with polyurethane foam reduce heat loss (≤3℃ drop in 24h at 5℃ ambient). Large capacity stores daytime hot water for night/early morning peak use and avoids temperature fluctuations.

Auxiliary Heating: Air-source heat pumps were added for Xi'an’s winter low-sunlight periods. When solar heat fails to reach 55℃ (set temperature), pumps activate to ensure year-round supply, avoiding high electric heating costs and solar "weather dependence."

Intelligent Control: Sensors monitor temperature, water level, and usage, adjusting pumps and heaters automatically. (teachers and students) check supply via campus APP; managers remotely troubleshoot, improving maintenance efficiency.

III. Operational Results: Triple Benefits

The system has run stably for nearly two years, delivering economic, environmental, and social gains.

Economic Benefits: It ends high-cost traditional supply, generating ~48,000 kWh equivalent electricity yearly—saving ~18,000 m³ natural gas and over 60,000 yuan in annual energy costs. With a 15-year lifespan, it saves nearly 900,000 yuan total, with a 5-year payback. Modular design cuts annual maintenance costs by ~12,000 yuan vs. boilers.

Environmental Benefits: It reduces annual CO₂ emissions by ~48 tons (equivalent to 16 tons of standard coal), SO₂ by ~1.4 tons, and NOₓ by ~0.7 tons—equal to planting 2,600 trees. It eliminates boiler noise and exhaust, creating a cleaner campus.

Social Benefits: Hot water is now "on-demand" (55-60℃, stable pressure) with >95% (teachers and students) satisfaction. A "Solar Popularization Corner" educates via displays and QR codes; student clubs run eco-activities, spreading low-carbon ideas and combining "energy transformation" with "education."

IV. Future Outlook: From Practice to Promotion

The project’s success offers valuable experience. The university plans to expand: (promote) the system to canteens and gyms, increasing supply to 25 tons/day and cutting fossil energy use; explore "solar + energy storage" with campus PV projects to build a "solar thermal + PV" green system for diversified clean supply.

It also aims to cooperate with local universities and enterprises to share experience, promoting solar use in education. As a Shaanxi campus energy pioneer, the project proves renewable energy—when aligned with regional resources and needs—enhances campus life and drives green development, contributing to "zero-carbon campuses" and cities.