In-depth Analysis: The Optimal Application Scenarios of Solar Thermal Energy + Air Energy Heating

The combined heating system using solar energy and air energy is essentially an energy-saving complementary model of "priority on solar heat + supplementary energy from heat pumps". Solar energy absorbs heat freely, meeting the basic heating needs; the air-source heat pump provides stable energy supply during periods of insufficient solar energy, such as on cloudy days and at night. This reduces the operating costs of traditional air-source heat pumps and compensates for the intermittent nature of solar heating. The core advantages of this combined solution are low carbon emissions, low operating costs, and strong stability. However, it is limited by factors such as the solar collector area, installation conditions, and climatic conditions, and may not be applicable in all scenarios.

01  Which scenarios are more economically reasonable?

The Solar Thermal Energy + air energy system, although having a high initial cost, can show greater economic efficiency in the following scenarios due to its high contribution rate:

1. Public and commercial buildings that enjoy substantial investment subsidies

In many regions, the clean energy renovation subsidy policies offer greater support to public buildings such as schools, hospitals, and nursing homes. The subsidies can directly offset the initial installation cost of the solar heating system, allowing the value of "free fuel" to be realized in a shorter period of time. 

2. Standard configuration for new low-energy buildings

In the pursuit of ultra-low energy and near-zero energy building standards, solar thermal utilization has become a "standard answer" type of technical option. Integrated design at the early stage avoids the costs and troubles of later installation, and the energy generated directly contributes to the energy balance target of the building, with a value higher than the simple savings in operating costs. 

3. Scenarios requiring a large amount of domestic hot water throughout the year

This is the area where the economic viability of solar energy is most indisputable. Scenarios such as hotels, swimming pools, bathhouses, and industrial hot water demands have stable domestic hot water requirements throughout the year. Solar systems operate non-stop throughout the year, and even generate excess heat in summer. In such applications, the annual utilization rate of solar energy is close to 100%, and the investment payback period is often the shortest (usually 3-6 years), and its relationship with heating is relatively less significant. Heating demand merely further increases the utilization rate of equipment in winter. 

4. Transitional areas where the heating season overlaps with the high-sunshine season

During the early winter and early spring in the northern region (such as November and March), the outdoor temperature is still acceptable, but the sunshine is still quite good. At this time, the solar energy system can almost independently meet the heating needs, while the air-source heat pump only needs to be activated in extremely cold or cloudy conditions. In these areas, solar energy effectively extends the "free heating period", and its value is very considerable. 

02  Specific Adaptation Scenarios 

(1) Large-scale heating scenarios for industrial factory areas and heating for production purposes 

Applicable objects: Industrial supporting buildings such as production workshops, storage warehouses, staff dormitories, and office buildings, especially suitable for industries with stable temperature requirements such as food processing, textile, and electronics.

Applicable reasons:

1. Stable and large heat load: The heating area of industrial plants is usually several thousand to tens of thousands of square meters, and some processes have low-temperature heating demands (such as maintaining a constant temperature of 20℃ in workshops, hot water cleaning, etc.). "Solar energy + air energy" can simultaneously meet heating and process heating needs, achieving energy cascade utilization.

2. Abundant site resources: Rooftops of industrial plants, parking lot ceilings, and idle open spaces can all be equipped with solar collectors, photovoltaic panels or PVTs. Some industrial plants can also combine with photovoltaic car shelters to achieve "solar power generation + heating" dual benefits. 

3. Significant energy-saving benefits: Industrial electricity costs are higher than those for residential use. Traditional electric heating or gas heating are costly. The combined system can significantly reduce heating energy consumption. 

Solution: Solar collectors + air energy, PVT + air energy, solar thermal + photovoltaic + air energy, and other energy coupling schemes. 

(II) Specialized tourism and accommodation projects such as cultural tourism inns and health care parks

Target audience: Tourism and accommodation projects that emphasize "green and low-carbon" brand image, such as inns clusters, forest health care bases, and hot spring resorts.

Adaptation reasons:

1. Alignment with brand positioning: The project positioning focuses on the concepts of "ecology, environmental protection, and health", and the solar energy + air energy heating system can serve as a core selling point, conveying the value of green and comfortable living to tourists.

2. Flexible heating periods: The heating demands of inns and health care parks mainly occur at night and during holidays. Solar energy can store heat during the day, matching the time-based heating patterns, further reducing operating costs. 

3. Environmentally friendly installation: Most of the residence projects are located in the suburbs or scenic areas, with good lighting conditions and scattered building layouts, which are suitable for distributed installation of solar collectors and have a high degree of integration with the natural landscape.

Solution: It is possible to combine the personalized design of the guesthouses and adopt a combination of solar collectors and air-source heat pumps, taking into account both aesthetics and practicality; a smart temperature control system is also provided to achieve room-by-room regulation and reduce energy waste. 

(III) Constant temperature heating scenario for agricultural planting and breeding greenhouses

Applicable objects: Seedling greenhouses, flower greenhouses, off-season fruit and vegetable greenhouses, livestock breeding sheds (such as piglets' sheds, poultry rearing sheds), etc., which are breeding and planting scenarios sensitive to temperature.

Applicable reasons:

1. Temperature demand matching: The heating demand of agricultural greenhouses is usually 5℃~25℃, which is a medium-low temperature heating requirement, and it perfectly matches the heating temperature range of solar energy + air energy heating.

2. Synchronization of light and heat usage: During the day, greenhouses need sunlight for photosynthesis, and solar collectors can simultaneously absorb heat for heating; when the temperature drops sharply at night, air-source heat pumps start to replenish heat to prevent crops and livestock from freezing. 

3. Agricultural subsidies boost: Many regions offer special subsidies for agricultural energy-saving facilities. The solar + air energy heating system can enjoy combined subsidies for agricultural machinery and energy conservation, reducing initial investment.

Solution: Use flat solar collectors (resistant to hail, easy to clean) or solar air collectors, combined with an air-source heat pump hot air system, to directly blow warm air into the greenhouse to improve heating efficiency; install temperature control sensors to achieve automatic temperature adjustment. 

(IV) Urban Central Heating Scenario

Applicable Objects: New residential communities in towns, heating renovation projects in old residential areas, especially suitable for small and medium-sized towns and county areas with better lighting conditions.

Applicable Reasons:

1. Heating Scale Adaptation: Urban centralized heating needs to meet the simultaneous heating requirements of multiple households and large areas. Solar collectors can expand the heat collection area through modular combination, and air-source heat pumps can flexibly adjust the output power according to the heating load, adapting to different scale heating demands.

2. Energy Saving and Cost Advantage: Central heating consumes a large amount of energy. Solar energy, as a free and clean energy source, can replace a large amount of conventional electricity and gas. Combined with the efficient energy-saving characteristics of air-source heat pumps (with a COP value typically ranging from 3 to 4), compared to traditional coal-fired or pure electric heating, it can significantly reduce long-term operating costs.

3. Policy and Environmental Requirements: Currently, local authorities strictly control coal-fired heating and vigorously promote clean energy heating. The solar + air-source system has zero pollutant emissions and is in line with the "dual carbon" goals and urban environmental protection policies. It can enjoy local special subsidies for clean energy heating and supporting funds for old residential area renovations.

4. Stability Meets Demand: Urban centralized heating has high requirements for system stability. During the day, it relies on solar collectors to meet basic heating needs. During periods of low sunlight such as rainy, snowy, or nighttime, air-source heat pumps quickly provide supplementary heating to ensure a constant indoor temperature (typically maintained at 8°C - 22°C), avoiding heating interruptions.

Solution: Use centralized solar collector arrays (vacuum tubes or EFPC large flat plate collectors, selected based on local lighting conditions), combine with large-capacity insulated water tanks to store heat, and use air-source heat pump units as auxiliary heat sources, connecting to the existing urban heating network; Configure an intelligent central control system to monitor the temperature, pressure of the network, and solar collector efficiency in real time, automatically switch heating modes, and support metering by households, taking into account energy conservation and users' individualized needs. 

03  Key Characteristics for Maximizing Solar Energy Contribution

(I) Climatic Characteristics: Abundant sunlight + Long-term coldness

1. Ideal Scenario: High-altitude and high-sunshine areas (Northwest, Qinghai-Xizang Plateau). Although the winter temperature is low, there are many sunny days, less cloud cover, and high solar radiation intensity. Solar collectors, under cold and sunny weather conditions, as long as they are protected against freezing, still have high heat collection efficiency, can provide considerable low-temperature heat, significantly reducing the load of heat pumps. The heat loss caused by the temperature difference can be compensated by enhancing insulation. 

2. Suitable environment: Regions with cold winters and hot summers, and areas with relatively abundant sunlight. For example, some parts of North China and the Huaihai region, where there is sufficient sunlight in winter, solar energy can meet the basic load requirements. 

3. Unsuitable scenarios: Cold and damp winter conditions, areas with long periods of low sunlight. For instance, regions such as the Sichuan Basin, Hunan, and parts of Guizhou, where the solar radiation in winter is severely insufficient, resulting in high idle rates of solar energy systems and poor economic efficiency. 

(II) Architectural Characteristics: Precise Heat Load Matching

1. Optimal Matching:

(1) Buildings where the peak heat demand during the day coincides with the peak solar radiation. For example: schools, office buildings, factory workshops, warehouses, etc. These buildings require heating during the daytime activity periods. Solar energy can be directly "instantly available" and does not need to go through long-term and high-loss storage. The system efficiency and contribution rate are the highest.

(2) Stable and large heat load usage: The heating area of industrial plants is usually several thousand to tens of thousands of square meters, and some processes have low-temperature heat demand (such as maintaining a constant temperature of 20°C in workshops, hot water cleaning, etc.). "Solar energy + air energy" can simultaneously meet heating and process heat demands, achieving energy cascade utilization.

(3) Year-round heat usage: There is a large demand for domestic hot water throughout the year. The annual utilization rate of solar energy is nearly 100%, significantly shortening the investment payback period, and winter heating can further improve equipment utilization. 

2. Good Match: Areas with stable base heat load. Such as constant-temperature swimming pools, aquaculture ponds, and greenhouse sheds. These places need to maintain a relatively stable temperature 24 hours a day. The free heat from the sun during the day can be directly injected to maintain the temperature or slow down the temperature drop, significantly reducing the consumption of conventional energy. 

Conclusion: 

From high-efficiency public buildings, newly constructed low-energy buildings, to specific urban centralized heating, industrial factory areas, distinctive tourism accommodations, agricultural production scenarios, and the hot water demand scenarios that require stable heating throughout the year. As long as they conform to the core characteristics of "suitable lighting conditions, stable heat load, and sufficient site resources", maximum solar energy utilization can be achieved, and the system operation costs can be minimized. 

BTE Solar is a full-chain provider specializing in "the application of clean thermal energy in all scenarios", dedicated to the development and application of various clean energy sources such as solar energy, geothermal energy, and air energy. It provides high-quality thermal energy, heating, cooling, and power services for building energy use, industrial heat supply, planting and breeding, drying, new infrastructure construction and other scenarios. As a national "small giant" enterprise with specialized and innovative characteristics, the proportion of researchers is 16%, among which 50% of the researchers have been in the industry for more than 20 years. They have obtained 117 core patents and solutions. They have several scientific research practice platforms such as the Shandong Provincial Academy of Sciences and the Shandong Provincial Doctoral Postdoctoral Innovation Practice Base. They continuously increase the in-depth research on technologies such as heat and power twin systems, cross-seasonal energy storage systems, energy transmission systems, and smart energy utilization systems, promoting the efficient integration and rapid development of the new solar energy + clean thermal energy industry.