Photovoltaic hot water engineering is divided into traditional centralized hot water engineering and centralized heat collection with centralized hot water supply projects. It involves replacing traditional flat plate or vacuum tube collectors with photovoltaic panels, using electrical wires instead of traditional circulation pipes, and utilizing the electricity generated by photovoltaic modules to directly power air-source heat pumps for heating water. This technical solution was first proposed, designed, and implemented by our company in 2016. With the reduction in the cost of photovoltaic modules, its advantages have become increasingly evident. Comparing a traditional solar hot water system with a photovoltaic hot water system for a 50-ton apartment building in a school clearly highlights the pros and cons of both.
| Category | 30-ton Traditional Solar + Air Energy Project | 30-ton Photovoltaic + Air Energy Project |
| One-time Investment | 450,000 RMB | 75 kW configured at 2.5 kW per ton of water, plus air-source heat pump, totaling 460,000 RMB |
| Thermal Efficiency | 55% | 0.2 (module efficiency) X 4.0 (average air energy efficiency) X 100% = 80% |
| Average Annual Operating Cost | Circulation pump runs 7 hours daily; pipeline insulation annual electricity cost: 7X1.0 kWhX0.8X365 + 10X15 kWhX60X0.8 = 9,244 RMB; pipeline maintenance cost about 2,000 RMB annually; total annual maintenance cost 11,244 RMB. During holidays when hot water is not used, the generated hot water is not only wasted but also harmful to the equipment. | No hot water needed during three months of holidays annually; power generation revenue: 75 kW X 4.2 X 90 days X 0.55 RMB/kWh = 17,355 RMB; maintenance cost 2,000 RMB. While meeting hot water demand, the remaining power generation yields an annual profit of 15,355 RMB. |
| Maintenance Rate | Pipeline leaks, insulation, signal cables, motors, etc., all require maintenance and have a lifespan. | Only electrical components and cables require maintenance. |
| Equipment Investment Return (Operation) Time | Equipment only generates value when students use hot water. Excluding holidays when students are not on campus, the annual valuable time is only about 250 days. | 365 days a year, generating value and benefits daily. |
| Benefit Generation Time | Equipment is installed ahead of infrastructure time and only put into use when students move in, realizing value. | Equipment is installed, connected to the grid, and generating electricity, producing economic benefits. |
