What is Solar Space Heating: A Comprehensive Guide

Solar space heating is a highly efficient and cost-effective way to heat the interior of a building using the power of the sun. This comprehensive guide will delve into the technical details of solar space heating systems, their components, and the various approaches to designing and installing these systems, including DIY options.

Understanding the Basics of Solar Space Heating

Solar space heating systems work by capturing the sun’s energy and using it to heat the air or a heat-transfer fluid, which is then distributed throughout the building. These systems can be classified into two main categories: passive and active.

Passive Solar Space Heating

Passive solar space heating systems rely on the building’s design and materials to collect, store, and distribute heat. This includes features such as:

  • Orientation: Positioning the building to maximize sun exposure, often with large south-facing windows.
  • Thermal Mass: Using materials like concrete, brick, or water to absorb and store heat during the day and release it at night.
  • Insulation: Proper insulation in walls, floors, and roofs to minimize heat loss.
  • Ventilation: Strategically placed vents and windows to allow for natural air circulation and heat distribution.

The advantage of passive solar space heating is its simplicity and lack of mechanical components, which can reduce maintenance and energy consumption. However, passive systems may have limited control over heat distribution and storage.

Active Solar Space Heating

Active solar space heating systems use mechanical equipment, such as pumps, fans, and blowers, to aid in the collection, storage, and distribution of heat. These systems can be further divided into two subcategories:

  1. Liquid-based Systems:
  2. Use a heat-transfer fluid, such as water or a water-antifreeze mixture, to collect and transport heat from the solar collectors to a storage tank or thermal mass.
  3. Typically include solar collectors, a storage tank, a heat exchanger, and a circulation pump.
  4. Offer more precise control over heat distribution and storage compared to passive systems.

  5. Air-based Systems:

  6. Use air as the heat-transfer medium, drawing cool air from the building, heating it in the solar collectors, and then returning the warm air to the living space.
  7. May involve closed-loop systems that recirculate the heated air or open-loop systems that draw in fresh outdoor air.
  8. Tend to be less complex and costly than liquid-based systems, but may have lower efficiency.

Key Components of Active Solar Space Heating Systems

what is solar space heating

Active solar space heating systems typically consist of the following essential components:

Solar Collectors

Solar collectors are the heart of an active solar space heating system, responsible for capturing the sun’s energy and transferring it to the heat-transfer fluid or air. Some common types of solar collectors used in these systems include:

  • Evacuated Tube Collectors: Highly efficient, with a vacuum-sealed glass tube design that minimizes heat loss. These collectors often have a selective coating to enhance absorption and are SRCC certified.
  • Flat Plate Collectors: Consist of a dark-colored absorber plate, typically made of copper or aluminum, enclosed in an insulated frame with a transparent cover.
  • Air Collectors: Use air as the heat-transfer medium, often with a dark-colored absorber plate or matrix to maximize heat absorption.

The size and number of solar collectors required will depend on factors such as the building’s heating load, the climate, and the desired system capacity.

Solar Storage Tanks

Solar storage tanks are used to store the heated fluid or air for later use. These tanks are typically made of durable materials, such as stainless steel or high-density polyethylene, and come with long-lasting warranties (often 10 years or more). The size of the storage tank is determined by the system’s heating demand and the number of solar collectors.

Solar Pumps and Blowers

Solar pumps and blowers are responsible for circulating the heat-transfer fluid or air through the solar collectors and the storage system. These components are carefully selected to ensure high performance and durability, often with features like variable-speed operation and energy-efficient designs.

System Controls and Monitoring

Active solar space heating systems typically include control systems and monitoring equipment to optimize the system’s performance and ensure safe operation. This may include:

  • Differential Temperature Controllers: Monitor the temperature difference between the solar collectors and the storage tank, activating the pumps or blowers when there is a sufficient temperature difference.
  • Sensors and Gauges: Track temperatures, pressures, and flow rates throughout the system to provide real-time performance data.
  • Automated Valves and Dampers: Regulate the flow of heat-transfer fluids or air to maintain the desired temperature and distribution.

Integrating Solar Space Heating with Existing Heating Systems

One of the key advantages of active solar space heating is the ability to integrate it with existing hydronic (hot water) or forced-air heating systems. This can be done by using the solar-heated fluid or air to supplement or replace the conventional heating source, such as a furnace or boiler.

The integration process typically involves the following steps:

  1. Solar Collector Loop: The solar collectors circulate a heat-transfer fluid, usually a water-glycol mixture, through the solar array, where it is heated, and then transferred back to the solar storage tank.
  2. Storage Tank Integration: As the heated fluid is circulated through the storage tank, the tank’s water is heated. This hot water can then be circulated through the existing heating system, such as a radiant floor or forced-air system, to provide space heating.
  3. Control and Monitoring: The system’s controls and monitoring equipment ensure that the solar-heated fluid or air is efficiently integrated with the existing heating system, optimizing energy usage and comfort.

By integrating solar space heating with an existing system, homeowners can maximize the benefits of solar energy while minimizing the need for major system replacements or renovations.

DIY Approaches to Solar Space Heating

For those interested in a more hands-on approach, it is possible to design and install a solar space heating system using readily available components. However, it is crucial to ensure that the system is designed and installed correctly to ensure safety, efficiency, and compliance with local building codes and regulations.

When considering a DIY solar space heating project, some key factors to consider include:

  • System Design: Carefully calculating the building’s heating load, selecting the appropriate solar collectors and storage components, and designing the circulation and distribution system.
  • Installation: Properly mounting the solar collectors, installing the storage tanks and piping, and integrating the system with the existing heating infrastructure.
  • Controls and Monitoring: Implementing the necessary control systems, sensors, and monitoring equipment to optimize system performance and safety.
  • Permits and Inspections: Obtaining the required permits and ensuring the system meets all local building and electrical codes.

It is highly recommended to consult with a solar heating professional or seek out resources and guides specifically tailored to DIY solar space heating systems to ensure a successful and safe installation.


Solar space heating is a versatile and effective way to reduce heating costs, increase energy independence, and contribute to a more sustainable future. By understanding the technical details of active solar space heating systems, their key components, and the potential for integration with existing heating systems, homeowners and DIY enthusiasts can explore the benefits of this renewable energy technology. With the right planning, design, and installation, solar space heating can be a valuable addition to any home’s heating solution.

Solar Panels Plus – Residential Solar Space Heating
Solar Energy at Home – Solar Space Heating
SEIA – Solar Heating and Cooling