Solar Heating Active vs. Passive, Which is Better

Solar panels are not the only method of capturing and using thermal solar energy. Although the idea of photovoltaic solar panels—which turn light into electricity—is commonly known, it’s not the sole way to use the sun’s energy. Although solar panels are the most common way to power your house, solar heating is an underappreciated technique that shouldn’t be disregarded.

Solar heating devices are not novel; humans have used them for thousands of years. For example, the ancient Greeks developed “sunrooms,” heated indoors by effectively capturing and storing solar energy.

Nearly one-third of all homes today have trouble affording their energy expenses. That being stated, homeowners can profit by investigating the various applications for solar heating panels or systems that can keep us cozy and significantly lower those outrageous expenses.

Obviously, homeowners may require assistance to pay for improvements. If your conventional heating system is too costly, upgrade it. Solar heating systems are a great choice if improving your system is something you can accomplish.

This extensive solar heating guide is here to help clarify your available solar heating options.

Solar Heating Options

Passive solar heating and active solar heating are the two ways thermal solar energy keeps buildings warm. Let’s look at the description and differences between these two methods below:

Passive Solar Heating

To decrease the need for home heating, passive solar heating methods incorporate the structural elements of a house to absorb, preserve, and disperse solar heat gains. Since this heat movement in a passive solar system occurs naturally through processes like convection, conductance, and radiation, and because the building itself serves as a thermal reserve, there is no need for mechanical components.

The following essential elements make up a passive solar heating system, and each one of them must function well for the concept to be practical:

  • Control

A passive solar heating system’s aperture (collector) is a sizable glass surface that lets light into the structure. Usually, throughout the summer period, from 9 a.m. to 3 p.m. every day, the aperture(s) must face within 30° of the real south and shouldn’t be blocked by any other structures or woods.

The absorber is the term for the storage element’s rigid, opaque top. This object, which may be a brick wall, floor, partition (made of a phase-change substance), or water reservoir, is situated in the direction of the sun’s rays. The heat from the sun is then absorbed onto the surface.

Materials that absorb or retain heat from sunlight make up the thermal mass. While both frequently constitute the same structure or flooring, the absorber and thermal mass vary because the absorber is a visible surface. In contrast, the thermal mass is the substance beneath or behind the covering.

The process by which solar heat is transferred from the accumulation and storage locations to other parts of the structure is known as distribution. Conduction, convection, and radiation are the only natural heat transport modes used in a purely passive design. But, in some situations, blowers, ducts, and fans may distribute heat throughout the structure.

Ceiling eaves, which can be utilized to cast the aperture region during the warmer quarters; electrical sensor systems, like a variable temperature sensor that indicates a fan to switch on; motorized ductwork and attenuators that enable or limit heat flow, low-emissivity shutters and canopies are components that assist control under- and overheating of a passive solar heating system.

How Does a Passive Solar Heating System Work?

Passive solar structures are made to permit heat inside the structure during the cold and keep the sunlight away during the sweltering summer. This can be done by using passive solar design components like shade, installing big windows that face south, and using construction materials that collect and gradually release heat from the sun.

Are Passive Solar Heating Systems Worth the Investment?

Unlike some other active solar heating systems, passive solar heating systems do not require a considerable upfront cost or a lengthy return on investment. Passive solar heating also has the benefit of improving consumer comfort. Passive solar structures are sunny and bright, as well as sensitive to the vagaries of the environment.

Hence, there are fewer temperature swings, which increases thermal convenience and temperature consistency. Passive solar buildings can help improve satisfaction and consumer productivity by offering a lovely location to reside and work. Additionally, passive solar architecture prevents the production of greenhouse gases and delays the depletion of fossil fuels.

Designing using passive solar energy has a few concerns. Firstly, the system must be given the most sunshine exposure possible to operate efficiently. Secondly, because sunlight’s intensity varies, it might overwhelm the system, which could have a negative impact on some electrical devices like laptops and air conditioning units. But, with the assistance of knowledgeable passive solar designers, engineers, and builders, passive solar architecture is only marginally more expensive up front but saves money in the long run.

In smaller structures where the exterior design regulates the energy requirements, passive solar heating performs better. This refers to areas where active individuals, lighting, electronics, and other interior heat gains do not currently heat.

All small structures in chilly and moderate areas should be equipped with low amounts of passive solar heating, also known as sun-tempering, which can cut auxiliary heating demands from 5% to 25% for minimal or no additional upfront expense.

Compared to conventional construction, more active passive solar heated structures can decrease heating energy usage by 25% to 75% while still being life-cycle cost-effective. This strategy should be considered for many small structures in cold and moderate areas.

Active Solar Heating

An active solar energy system is known as a solar water or room heating system that employs motors or blowers to control flow from solar collectors to a holding tank subsystem. Depending on the kind of fluid heated in the solar energy collectors—liquid or air—there are two fundamental types of active solar heating systems. Air-based technologies heat air in an air collector, while liquid-based systems heat the water or even an antifreeze mixture in a “hydronic” concentrator.

Both of these methods gather and take in sunlight before transferring the heat immediately to the indoor area or to a backup system, where it is subsequently dispersed. An auxiliary or backup system delivers extra warmth if the primary system cannot offer sufficient area heating. When reserve is present, liquid methods are more frequently employed and are ideal for absorption heat pumps, coolers, and boilers with hot water radiators. Systems that use liquid or air can be added to forced air systems.

  • Solar Air Space Heating

Utilizing indoor air heaters, solar air space heating effectively heats your living area. Cold air is drawn into a solar concentrator by a roof- or wall-mounted air heater, where it is heated before being pushed back into space. Vents are utilized to push hot air into the space from ceiling heaters. Additionally, holes are constructed in the walls for air to flow through when wall-mounted room warmers are installed on south-facing surfaces.

  • Solar Water Heating Systems

A solar concentrator in solar-powered water heaters (hydronic systems) absorbs sunlight and transforms it into heat. To transmit the thermal energy generated by the solar collectors to the liquid, either water or a non-toxic glycol coolant runs through the plates. The temperature of the water rises to 10–20°F (5.6–11°C) as it moves swiftly through the solar collector—the fluid moves from the heat converter or water reservoir to another.

Heat Distribution for Liquid Systems

To disperse the solar heat, you can utilize a radiant floor, hot water baseboards or radiators, or a central forced-air system.

  • Radiant Floor Method

In a radiant floor method, a liquid heated by the sun is pumped via pipes set into a lightweight concrete block floor, which distributes heat throughout the space. Liquid thermal solar systems benefit significantly from radiant floor heating because they operate effectively at cold temperatures. Compared to other kinds of heat distribution systems, radiant slab systems take longer to “warm up” the house from a chilly start. But once they start working, they deliver a steady stream of heat.

  • Hot Water Baseboards or Radiators

To efficiently heat a space, hot-water baseboards and radiators need water between 160° and 180°F. Flat-plate liquid collectors typically heat the transmission and circulation fluids to temperatures between 90° and 120°F. To use baseboards or radiators with a solar heating system, it is necessary to increase their contact area, elevate the temperature of the sun-heated liquid utilizing a storage service, or swap out flat-plate collectors with moderate-temperature solar collectors like vacuum tube collectors.

  • Central Forced-Air System

Before the primary room-air return pipe enters the burner, the preliminary layout calls for installing a liquid-to-air heat exchanger known as a heating coil. As it passes through the liquid in the exchanger heated by solar energy, the air coming from the living area is warm. The furnace supplies extra heat as needed. At the relatively low operating temperature of the absorber, the coils should be big enough to transmit sufficient heat to the air.

Both active and passive solar heating systems support the heating system in your home by distributing heat where it is most needed. You won’t have to pay the astronomical electricity costs associated with traditional heaters when you use solar space heating. Your existing heating system can be cost-effectively supplemented with solar energy.

Are Active Solar Heating Systems Worth the Investment?

An operational home solar heating system will range in price. Widely viable collectors have at least a ten-year warranty and should last many more years. An active space heating system can operate more economically by using a typically inactive collector to heat water in the summertime.

Using an active solar energy system to heat your home can drastically lower winter heating costs. A solar heating system will help lessen the quantity of greenhouse gasses and air pollution produced when you heat your home or generate energy using fossil fuels.

Difference between an Active Solar Heating System and Passive Solar Heating System

The main distinction between active and passive solar heating is that active solar heating converts solar energy into heat or electricity for use in mechanical equipment to heat homes. In comparison, passive heating uses the heat that the sun emits when it enters your house via walls, roof, and windows to warm the things inside. Other differences between these two solar heating systems are as follows:

  • Pumps, blowers, and other mechanical components are used to run active systems. Unlike them, passive systems utilize sunlight effectively.
  • Active systems don’t require unique architectural considerations.
  • Active systems require separate collectors, whereas passive systems use a part of the building to collect solar light.
  • Nearly any type of construction and location is suitable for using active systems.
  • The cost of building and running an active solar heating system is higher than that of a passive one.

Active vs. Passive Solar Heating System: Which Way to Go?

The advantages of active solar energy include the fact that it only uses the sun as a power supply. Additionally, active solar energy uses durable, low-maintenance exterior solar panels.

But compared to active solar energy, passive solar energy is usually less expensive. Sadly, passive solar energy is more influenced by the weather. In a warm region, you may also risk overheating a structure because you won’t be able to control the temperature as efficiently.

The energy captured by your solar thermal panel can be used for purposes other than only heating, which is why we prefer active solar in the end. You can power your stove, lighting, air conditioner, and any other appliance that uses electricity in your house.

Kateryna Ryzha

Kateryna Ryzha

Kateryna is an experienced writer with a focus in solar energy. She is a specialist in several topics related to energy efficiency, technical applications, renewable energy, and more as a consequence of her extensive reading.

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