The History and Science Behind Solar-Heated Homes

By Ibtisam AbbasiReviewed by Lexie CornerFeb 6 2025

The demand for sustainable and energy-efficient solutions has driven research into alternatives to conventional fossil fuels. Fossil fuel-based combustion processes release greenhouse gases and harmful byproducts. These issues can be mitigated using renewable energy sources, with solar energy being a leading option.¹ 

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The Drover Sun House: A Historic Milestone

A significant development in solar heating occurred with the Dover Sun House in 1948. Designed by Massachusetts Institute of Technology (MIT) engineer Dr. Maria Telkes, along with architect Eleanor Raymond and sculptor Amelia Peabody, this project pioneered the use of thermal storage for residential heating.²

The house featured a second-floor thermal energy collector directing warm air into three heat storage bins.³ The collector consisted of a double-layered plate glass system with an air-filled gap and an 800 sq. ft. black metal sheet, installed on the south-facing wall. Fans circulated the heated air into bins containing metal drums filled with Glauber salts (sodium sulfate decahydrate).

As the air passed around the drums, the salt melted, storing heat at a constant temperature. When the surrounding air cooled, the salt recrystallized, releasing the stored heat. Warm air was then distributed into each room using fans. The thermal heating system failed after three years of continuous operation; however, the chemical thermal heating systems conceptualized by the researchers are still in use.

Scientific Principles of Solar Heating

Thermodynamics

Solar heating systems operate by capturing solar radiation through specialized devices such as solar ponds and solar concentrators. These systems convert solar energy into thermal energy by increasing the temperature of a working thermal fluid. Depending on specific applications and efficiency requirements, engineers implement various solar thermodynamic power cycles to optimize performance.

The first and second laws of thermodynamics are used to evaluate and optimize solar heating systems. The second law applies to performance evaluation through exergy balance calculations of thermal components. While the absorption and emission of solar radiation are thermodynamically irreversible, the transmission of solar radiation is reversible.⁴

Phase-Change Materials

Phase-Change Materials (PCMs) are used to store and utilize solar radiation in specially designed solar thermal systems. Their application in Thermal Energy Storage (TES) has increased over the past 20 years. PCMs are classified into three categories: organic, inorganic, and eutectic. Organic latent PCMs are commonly used in solar heating systems, thermal energy storage, and space applications.

Experimental studies indicate that PCMs improve the efficiency and performance of solar heating systems. One example is solar thermal electricity (STE) power plants, which generate heat and electricity using high-temperature steam produced by solar radiation. Researchers have proposed incorporating PCMs into Solar Thermal Energy (STE) power plants to enhance heat and electricity generation. These PCMs offer near-isothermal, high-latent-heat storage, enabling more efficient and cost-effective energy conversion.⁵

Solar Collectors

The use of solar collectors in domestic and industrial heat generation has increased in recent years. Solar water heating (SWH) systems are a common example of solar thermal collectors used to improve efficiency and reduce costs in renewable energy applications. These systems are gaining attention due to their low cost, minimal environmental impact, and durability. However, their efficiency depends on the solar insolation of a given region.

A new technology combining solar thermal collectors with heat pumps has been developed for solar heating systems. This system, called the Solar-Assisted Heat Pump (SAHP), has improved the efficiency of solar-heated homes by reducing electrical energy demand.

Among the different types of solar collectors, flat plate collectors (FPCs) are the most commonly integrated into residential and small commercial solar heating systems. Their operating temperature ranges from 30 to 80°C, making them a practical choice for solar-powered homes.⁶

Advancements in Solar Heating Technology

Solar Collectors

Researchers have explored various strategies to enhance the performance of solar collectors in solar heating systems. The use of nanotechnology, specifically nano-fluids, has shown promising results in improving the thermal properties of solar collectors.

Nano-fluids increase the thermal efficiency of solar-based systems by enhancing heat transfer. Spiral tube solar collectors have been integrated into photovoltaic (PV) cells and heating systems, with nano-fluids improving both electrical efficiency and thermal performance. The increased heat transfer rate in these collectors has contributed to more efficient solar-heated buildings.⁷

One study investigated the effects of an internally grooved solar collector plate combined with an Al₂O₃-based nano-fluid. The researchers tested a flat plate collector using different nanoparticle concentrations—0.01 %, 0.05 %, 0.1 %, and 0.2 %—and mass flow rates of 0.024 kg/s, 0.036 kg/s, and 0.048 kg/s.

The highest efficiency was observed at a mass flow rate of 0.036 kg/s with an Al₂O₃ concentration of 0.2 %. Efficiency improvements over a standard collector using plain fluid were recorded as 46.37 %, 54.13 %, and 33.83 % for the tested mass flow rates, respectively.⁸

These results indicate that both collector geometry and the use of nano-fluids enhance the thermal performance of solar collectors, improving the overall efficiency of solar heating systems.

Hybrid PV-Thermal Collectors

Solar energy is a sustainable resource used in various cost-effective and reliable ways to generate electricity and heat, either through PV technology or thermodynamic cycles in concentrated solar power (CSP) systems.

A recent advancement in solar technology is hybrid PV-thermal (PV-T) collectors, which generate both electricity and thermal energy from the same aperture area. These systems achieve combined efficiencies above 70 %, outperforming standalone PV or thermal systems.

PV-T collectors have been demonstrated in cost-effective hot water tanks for thermal storage and batteries for electricity storage. They are particularly suitable for urban applications, where both thermal and electrical energy are needed, and space efficiency is a priority.

Additionally, PV-T collectors can be integrated with other solar technologies, such as PV panels or solar thermal (ST) collectors, to balance heating and electricity supply based on specific energy requirements while supporting sustainability.⁹

Latest Research and Future Trends

Zero-emission residential and industrial buildings are key to achieving the UN Sustainable Development Goals (SDGs). One efficient method for heating these buildings is the use of parabolic trough collector (PTC) systems. These systems use an absorber to capture concentrated sunlight reflected by mirrors. PTC systems are commonly used to generate steam for heating homes, powering restaurants, and supporting industrial processes.

A recent study by Ubaidullah et al. explored the use of PCMs in a novel PTC absorber to improve efficiency and reduce energy waste. The study tested a PCM-based absorber designed to optimize solar energy utilization for heating applications.

The researchers used PTC technology to focus sunlight on a finely ground PCM absorber. The efficiency of the absorber was tested by modifying the number of fins in different configurations. The study examined heat transfer improvements with fins arranged at angles of 180 °, 90 °, 45 °, and 30 °.

Results showed that adding fins inside the absorber created turbulence in the heat transfer fluid (HTF), improving heat transfer. The highest recorded room air temperature, approximately 35 °C, was achieved using an absorber with 12 fins. This configuration also resulted in the highest average energy and exergy values, measured at 72.3 % and 7.05 %, respectively.¹⁰ The 12-fin absorber design represents a step toward more efficient solar-heated homes and net-zero emissions.

Advancements in solar heating continue with the development of new materials, collectors, and absorbers. Improvements in nanotechnology and neural networks will allow researchers to analyze the effects of nanofluids and different fin shapes more efficiently. Ongoing innovations in solar heating systems will play an essential role in future sustainable energy solutions.

To stay informed about the latest advancements in solar heating technology and energy efficiency, explore these resources:

• Photovoltaic Materials for High-Efficiency Solar Cells: Recent Developments
• What is an Optical Rectenna and How is it Used for Energy Harvesting?
• Should We Use Graphene in Solar Panels?
• How Are Material Advancements Shaping Energy-Efficient Cooling?
• Could Thermophotovoltaics be a Solution to Cost-Effective, Sustainable Energy?
• Machine Learning-Optimized Graphene Metamaterial Solar Absorber Using Al-TiN-Fe

 References and Further Reading

1. Ge, T., et al. (2018). Solar heating and cooling: Present and future development. Renewable energy. https://doi.org/10.1016/j.renene.2017.06.081
2. Massachusetts Institute of Technology (MIT). (2024). MIT Buildings: Dover Sun House. [Online] MIT. Available at: https://libguides.mit.edu/c.php?g=175920&p=1160875. [Accessed on: January 13, 2025].
3. Yale Energy History. (1948). Eleanor Raymond and Maria Telkes, Dover Sun House, Dover Massachusetts, 1948. [Online] Yale. Available at: https://energyhistory.yale.edu/eleanor-raymond-and-maria-telkes-dover-sun-house-dover-massachusetts-1948-gallery/ [Accessed on: January 14, 2025].
4. Gupta, M., et al. (2015). Thermodynamic performance evaluation of solar and other thermal power generation systems: A review. Renewable and Sustainable Energy Reviews. https://doi.org/10.1016/j.rser.2015.05.034
5. Javadi, F., et al. (2020). Performance improvement of solar thermal systems integrated with phase change materials (PCM), a review. Solar Energy. https://doi.org/10.1016/j.solener.2020.05.106
6. Ahmed, S., et al. (2021). Recent progress in solar water heaters and solar collectors: A comprehensive review. Thermal Science and Engineering Progress. https://doi.org/10.1016/j.tsep.2021.100981
7. Alshuraiaan, B. (2024). Strategies to improve the thermal performance of solar collectors. Journal of Non-Equilibrium Thermodynamics. https://doi.org/10.1515/jnet-2023-0040
8. Chilambarasan, L., et al. (2024). Solar flat plate collector's heat transfer enhancement using grooved tube configuration with alumina nanofluids: Prediction of outcomes through artificial neural network modeling. Energy. https://doi.org/10.1016/j.energy.2023.129953
9. Herrando, M., et al. (2023). A review of solar hybrid photovoltaic-thermal (PV-T) collectors and systems. Progress in Energy and Combustion Science. https://doi.org/10.1016/j.pecs.2023.101072
10. Satish, T., et al. (2024). Building heating by solar parabolic through collector with metallic fined PCM for net zero energy/emission buildings. Case Studies in Thermal Engineering. https://doi.org/10.1016/j.csite.2023.103862

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