Community-installed "Photovoltaic and Solar Thermal Combined" System, Saves Electricity and Makes Money? Actual Data from This Shanghai Project Is Here

1. Why Develop a PVT Community Energy Integration System? In recent years, traditional energy sources have been decreasing, and burning coal and oil pollutes the environment. Therefore, everyone is trying to improve energy efficiency and use more clean energy like electricity and solar power. Energy waste in communities is actually quite serious—for example, air conditioning, hot water, and lighting each use different systems, which is inefficient and costly. Later, someone developed a "community energy station," which is basically a small energy center built within the community that converts clean energy sources like solar and air energy into electricity, cooling, and heating directly for residents. The "PVT community energy integration system" we are discussing today is a standout among community energy stations. It combines photovoltaic panels and heat generation, producing both electricity and heat, making it much more cost-effective than traditional systems.

2. Advantages and Applicable Scenarios of the PVT System Let me first tell you why the PVT system is so good. Ordinary photovoltaic panels convert most of the sunlight into heat waste when exposed to the sun. When the panel temperature rises, the power generation efficiency decreases—about 0.4% to 0.5% efficiency loss for every 1°C increase. The PVT system adds microchannels under the photovoltaic panels with circulating working fluid, which lowers the panel temperature, improving power generation efficiency and using the collected heat to produce hot water and heating—achieving two goals at once. Moreover, this system is built within the community, close to users, avoiding long-distance power transmission like large power plants, reducing energy loss and transmission costs, and making electricity use safer. Its scale is not large, mainly meeting the community's cooling, heating, and electricity needs. It can be used in residences, schools, and office buildings, especially suitable for buildings that require a large amount of hot water and have sufficient roof area.

3. Actual Measurement of the PVT Project in Shanghai Sheshan Community Let's take a specific example from a project in Sheshan North, Songjiang District, Shanghai. This project is a three-story public building equipped with a PVT integrated system responsible for air conditioning cooling and heating on the first and second floors, hot water for office handwashing and security showers, and also powers equipment and lighting.
1. Key Project Design Data First, here are some key data: The system's total cooling load is 45.76 kW, total heating load is 30.62 kW, which translates to 120 W per square meter for cooling and 80 W per square meter for heating. It is equipped with one scroll-type air-cooled heat pump unit. Considering not all rooms use air conditioning simultaneously, the selected unit's cooling capacity is 38.2 kW—summer supply and return water temperatures are 7°C to 12°C, and winter heating is 45°C to 40°C. The air conditioning system uses fan coil units, with air supplied and returned from above; each room's temperature is controlled by valves on the return water pipes, and the fan speed can be manually adjusted in three levels. The water system uses a single pump with constant flow and two-pipe system; the water pump can vary flow according to load; system pressure is maintained by a high-level expansion tank, and condensate water is drained into the bathroom's water well. Two circulation pumps were selected, each with a flow rate of 8 m³/h and a head of 20 mH. ₂ One pump is used while the other is standby; the effective volume of the high-level expansion tank is 0.5 m³. The core component is the PVT panels—56 panels in total, with a total installed capacity of 15.12 kW, each panel having a standard power of 270 Wp and dimensions of 1640 mm × 992 mm × 40 mm. Regarding power generation, electricity generated by the PVT panels is prioritized for community self-use; surplus electricity is fed into the grid, and any shortfall is supplemented from the grid.
2. System Performance Test Results To test the system's performance, we conducted tests under different conditions according to national standards, installed sensors to record real-time data such as current, voltage, temperature, and flow, and compared the PVT panels with ordinary photovoltaic panels of the same model to see how much better the PVT system is. The tests focused on three aspects: how well the system design and components operate, how to optimize control parameters, and how to improve the system, ultimately providing data support for promotion. The tests were conducted in actual outdoor environments, measuring a single PVT panel for a whole day, including power generation and heating performance, with data collected every 15 seconds. To ensure accuracy, we used the control variable method, keeping the system's water flow constant, then calculated daily power generation, power generation efficiency, hot water production, and heating efficiency based on power output and inlet/outlet temperature differences. Comparing with ordinary photovoltaic panels (PV): on the test day, solar irradiance was 23.91 MJ; the PVT panel generated 0.96 kWh of electricity, while the ordinary PV panel generated only 0.9 kWh; the daily electrical efficiency was 14.48% for PVT and 13.48% for PV. For heating, the PVT panel produced 6.13 MJ of hot water, with a daily thermal efficiency of 25.62%, and a combined efficiency (power generation + heating) reaching 40.1%, with a weighted efficiency as high as 63.72%. Looking at overall system efficiency: the PVT panel's photovoltaic conversion efficiency was 15.5%, compared to 13% for ordinary PV panels, an increase of about 19%; thermal efficiency of the PVT panel reached 25%, while ordinary PV panels cannot utilize heat at all; combined efficiency of the PVT panel was about 40.5%, compared to only 13% for ordinary PV panels. Regarding heat pumps, this system uses a dual-source heat pump with a COP (Coefficient of Performance, higher is more energy-efficient) of about 6.5, while ordinary air-source heat pumps have a COP of only 4.2, showing significant energy savings. Simply put, the PVT panels use microchannels to remove heat, lowering panel temperature and increasing power generation efficiency, while the excess heat serves as a heat source for the dual-source heat pump, greatly improving the overall system utilization.
3. Project Economic Analysis: How Long to Break Even? After discussing performance, let's talk about the money everyone cares about. This system can simultaneously provide cooling, heating, and electricity. Cooling and heating can be metered and charged, generating some income to offset operating costs; photovoltaic power generation reduces owners' electricity bills, and surplus electricity sold to the grid can also earn money. Coupled with government subsidies, the cost can be gradually recovered. Moreover, the system's design life is 25 years, ensuring stable long-term returns.
4. Investment and Operating Costs First, calculate the investment: the total system investment is 363,466 yuan, with a project building area of about 730 square meters, resulting in an investment of 497.9 yuan per square meter. Then calculate the average annual operating cost: the total operating cost is 51,109.34 yuan, of which the hot water part is 18,176.80 yuan, the air conditioning part is 32,008.54 yuan, and the power generation part is 924 yuan. 2.4.2 Income and profit situation: income is divided into the first 5 years and after 5 years: the total annual income for the first 5 years is 88,907.86 yuan, and after 5 years it is 80,710.63 yuan. Breaking it down, the annual income from hot water is 28,032 yuan, air conditioning is 36,440.93 yuan; the power generation part is 24,434.93 yuan for the first 5 years, and 16,237.70 yuan after 5 years (mainly due to subsidy changes). Finally, calculate the profit: the total annual profit for the first 5 years is 37,798.52 yuan, and after 5 years it is 29,601.29 yuan per year. From these data, it can be seen that relying solely on charges for hot water and air conditioning, there is still profit after deducting operation and maintenance costs; the investment in photovoltaic power generation can be recovered in 5 years; the overall system investment payback period is slightly longer, about 10 years to fully recover. Although there is an initial investment, the system can be used for 25 years, with stable subsequent income, so it still has investment value.

5. Impact of Environmental Parameters on the System In our tests, we found that environmental parameters have a significant impact on system operation, mainly in two aspects. The first is solar irradiance. When the PVT panel temperature can be controlled, the greater the irradiance, the more power is generated and the more heat is collected. In summer, when solar radiation is strong, the advantage of PVT panels over ordinary PV panels is more obvious — because ordinary PV panels have higher temperatures in summer, causing efficiency to drop more, while PVT panels can cool down in time, showing their efficiency advantage. The second is outdoor temperature and wind speed. These two factors mainly affect system heat dissipation. Under the same other conditions, the higher the outdoor temperature and the lower the wind speed, the less heat loss the system has, and the higher the thermal efficiency.
6. Social and Environmental Benefits of the System Currently, the country strongly encourages the use of renewable energy such as solar energy, and the Renewable Energy Law explicitly supports solar grid-connected power generation. Installing this system can reduce the consumption of conventional energy like coal on one hand, and on the other hand, it does not emit harmful gases nor consume water resources, making it very environmentally friendly. Enterprises installing this system can respond to national policies, use green electricity, and enhance their social image. Moreover, in the long run, its energy-saving and environmental benefits are considerable. We calculated the average annual environmental benefits of this Sheshan project: the system generates 18,900 kWh of electricity annually, obtains 26,426.23 kWh of heat annually, totaling an equivalent annual electricity production of 45,365.23 kWh. Converted to coal savings, it is 18.15 tons; reduces carbon dioxide emissions by 45.37 tons, sulfur dioxide by 1.36 tons, nitrogen oxides by 0.09 tons, and smoke dust by 1.23 tons. It should be noted that sulfur dioxide and nitrogen oxides cause acid rain, harming plants and aquatic life. This system can reduce these pollutants, which is quite meaningful for ecological protection.
7. Summary: Is the PVT System Worth Promoting? Overall, the PVT community integrated energy system combines PVT and dual-source heat pumps very well, simultaneously addressing the three major needs of air conditioning, electricity, and hot water. The circulating working fluid inside can both reduce the PVT panel temperature and improve power generation efficiency, and also serve as the heat source for the heat pump, raising the water supply temperature and increasing the heat pump's COP, significantly improving the overall system energy efficiency. Moreover, it saves energy, has good economic benefits, reduces pollutant emissions, and is environmentally friendly. There is already a successful demonstration project in Sheshan, Shanghai, and it can be fully promoted in more communities in the future, allowing more people to enjoy this efficient and environmentally friendly energy use method.