2014-12-31-IRENA-Solar_Heating_and_Cooling_for_Residential_Applications_44页_2mb

Summary of Solar Heating and Cooling for Residential Applications

Core Content

Solar heating and cooling (SHC) systems are renewable energy technologies that convert solar radiation into thermal energy for domestic hot water and space heating/cooling. These systems are mature and have been successfully implemented in several countries for over three decades. Despite their potential, global deployment remains limited, with only 1.2% of residential heating and cooling demand currently covered by solar thermal systems.

Main Points

1. Technology Overview

• Solar Thermal Systems (STS) convert solar energy into heat, which can be used for hot water, space heating, and cooling.
• The solar collector is the key component, with two dominant types:
  • Flat-plate solar collectors (FPC): Common in many regions, with a global share of ~26%.
  • Evacuated tube solar collectors (ETC): More efficient, especially in cold climates, with a global share of ~65%.
• Other types include:
  • Thermosyphon (passive) systems: Account for ~75% of installed capacity, mainly used in warm climates.
  • Pumped (active) systems: Used in a variety of climates, including colder ones with additional insulation.
  • Integral collector storage (ICS): Less efficient but cheaper, suitable for certain applications like evening hot water use.

2. Market and Deployment

• High penetration in countries like Cyprus, Israel, and China, where government mandates and local manufacturing have supported widespread adoption.
• Low penetration globally, with most countries still relying on conventional heating and cooling technologies.
• Key drivers for deployment include:
  • Government mandates and subsidies.
  • Cost competitiveness with gas and electric alternatives.
  • Local manufacturing and economic development.
• Challenges include:
  • High upfront costs in developed countries.
  • Integration into existing housing.
  • Competition with heat pumps and solar PV systems.

3. Cost and Performance

• Cost varies significantly by country and system type, influenced by:
  • Quality of solar collectors.
  • Labour costs.
  • Climate conditions.
• Cost competitiveness:
  • In Europe, STS are already cheaper than gas and electricity heating.
  • In the US, costs need to decrease by 3–5 times to be competitive with gas boilers.
  • In China, STS have lower capital costs but shorter lifespans compared to other countries.

4. Applications and Potential

• Residential applications are the primary focus, with most systems used for domestic hot water.
• Solar combi-systems provide both hot water and space heating, with a solar share typically around 25%, but up to 60% in some cases.
• Solar district heating is an emerging application, particularly in countries like Denmark and China, where large systems can meet up to 50% of heating demand in urban areas.
• Solar cooling is gaining traction, especially in regions with high cooling demand (e.g., Middle East), and is often integrated with solar thermal systems or used in conjunction with heat pumps.

5. Technical and Economic Considerations

• Efficiency of STS depends on climate, system design, and integration with storage and heat exchangers.
• Storage is essential for using thermal energy when the sun is not available.
• Cooling systems use solar thermal energy in thermally driven chillers.
• Future developments aim to improve system efficiency, reduce costs, and enhance integration into buildings.

Key Challenges and Opportunities

• Lack of international certification schemes hinders widespread deployment.
• Regulatory and awareness gaps among users and professionals.
• Competition from other technologies (e.g., heat pumps, solar PV) presents a challenge.
• Government support is crucial, especially for low-income and social housing.

Conclusion

Solar heating and cooling systems offer a sustainable and economically viable alternative for residential energy use, particularly in regions with high heating or cooling demands. While they are already well-established in certain countries, broader adoption requires addressing cost barriers, improving regulatory frameworks, and promoting international standards. With continued innovation and policy support, STS can play a significant role in reducing energy demand and promoting renewable energy use in the buildings sector.