Active Solar Heating |Difference Between Active and Passive Solar System

Active solar heating systems use solar energy to heat a liquid (liquid or air) and transfer the solar heat directly to a storage system for internal or later use. If the solar system cannot provide sufficient heating, an auxiliary or backup system will provide additional heat.

Liquid systems are most commonly used when storage is included and are suitable for radiant heating systems, boilers with hot water radiators, as well as absorption heat pumps and coolers. Both liquid and air systems can complement forced air systems.

Liquid-Based Active Solar Heating

Liquid-based active solar heating

Liquid solar collectors are ideal for central heating. They are also used in the solar system to heat household water. Flat collectors are the most common, but tubes and concentrator manifolds are also available. In collectors, heat transfer or “working” liquids, such as water, antifreeze (usually non-toxic propylene glycol), or other types of liquids, absorb heat from the sun. Over time, the controller operates a circulation pump to move the liquid through the manifold.

The liquid flows so rapidly that the temperature only rises from 5.6 ° to 11 ° C (10 ° to 20 ° F) as it moves through the manifold. Heating a small amount of liquid to a high temperature increases the heat loss from the collector and reduces the efficiency of the system. The liquid flows into the storage tank or heat exchanger and is ready to use. Other system components are pipelines, pumps, valves, expansion vessels, heat exchangers, storage tanks, and controls.

The flow rate depends on the heat transfer fluid. For more information on types of liquid solar collectors, their size, maintenance, and other issues see the active solar heating system.

Heat storage in a liquid system

Liquid systems store solar heat in a mass of walls in a water tank or radiant panel system. In a tank storage system, heat is transferred from the working fluid to the distribution fluid in the external heat exchanger on or in the tank.Heat storage in a liquid system

Depending on the system design, the tank is either under pressure or under pressure. Before choosing a storage tank, consider its cost, size, duration, location (basement or outdoor), and installation. If the required size of the tank does not fit on the existing port, you may need to build the tank in the field. Tanks also have temperature and pressure limits and must comply with local structural, hydraulic, and mechanical regulations.

You also need to pay attention to the amount of insulation needed to prevent excessive heat loss and the type of protective coating or seal needed to prevent corrosion and leakage.

Systems with very high storage requirements may require special tanks or customized tanks. They are usually made of stainless steel, fiberglass, or hot plastic. The option is also a concrete and wooden tank (Whirlpool). Each type of tank has its strengths and weaknesses, and all types need to be carefully placed due to their size and weight. It may be more practical to use multiple small tanks instead of one large tank.

The simplest option for a storage system is to use a standard water heater. They meet building regulations regarding pressure vessel requirements, have a corrosion-resistant coating, and are easy to install.

Heat distribution of liquid system

Radiant floors, skirting boards, hot water radiators, or central ventilation systems can be used to disperse the solar heat. In a flooring system, solar-heated fluid circulates through pipes embedded in the floor of a thin concrete slab, radiating heat into the room.

Underfloor heating works well at relatively low temperatures, making it ideal for liquid solar systems. A carefully designed system includes it for temperature control, but may not require a separate heat storage device. Even traditional boilers or standard water heaters can provide reserve heat.

Slabs are usually finished with tiles. Panel radiation systems take longer to warm home from a “cold start” than other types of heat distribution systems. However, when it operates, it provides a certain level of heat. Carpets reduce the effectiveness of the system. For more information, see Radiant heating.

Baseboards and hot water radiators require 71 ° to 82 ° C of water to effectively heat the room. In general, flat plate liquid collectors are heat transfer and distribution liquids from 32 ° to 49 ° C (90 ° to 120 ° F). Therefore, to use the baseboard or radiator in a solar heating system, the surface of the baseboard or radiator must be raised.

It is necessary to replace the temperature of the liquid heated by the sun through a backup system or a medium-temperature solar collector (such as a tube collector). Flat plate collector.

There are several ways to incorporate a liquid system into a forced-air heating system. The basic design is to place a liquid-to-air heat exchanger or heating coil in the air return duct in the main room before reaching the furnace. The return air from the living space is heated as it flows over the solar-heated liquid in the heat exchanger. Additional heat is supplied from the furnace as needed. The coil must be large enough to transfer sufficient heat to the air at the minimum operating temperature of the collector.

Ventilation preheating

Solar heating systems use air as the working medium for absorbing and transmitting solar energy. Solar air collectors can heat individual rooms directly or preheat the air that passes through the air coil of a heat recovery fan or air heat source heat pump.Ventilation preheating

Heat collectors generate heat earlier and later in the day than liquid systems, so they can generate more energy available during the heating season than liquid systems of the same size. Unlike liquid systems, air systems do not freeze, and small leaks in manifolds or ducts affect performance but do not cause serious problems. However, solar air collectors are less efficient than liquid solar collectors because air is a less efficient heat transfer medium than liquids.

Some early systems used solar hot air through the bedrock to store energy, but inefficiencies, potential problems with condensation and mold in the bedrock, and the effects of its moisture and mold. Therefore, this approach is not recommended. About indoor air quality.

Solar air collectors are often built into walls and roofs to hide their appearance. For example, a tiled roof can incorporate an airflow path to harness the heat absorbed by the tile.

Most solar heating systems are indoor air heaters, but relatively new devices called breathable air collectors have limited home use.

Room air heater

The heat collector can be installed on the roof or exterior wall (facing south) to heat one or more rooms. Factory-manufactured manifolds can be installed on-site, but if you do it yourself, you can build and install your own air manifold. A simple heating collector for a window unit can be made for hundreds of dollars.

The collector features a sealed insulating metal frame and a black metal plate for heat absorption with glass on the front. Solar radiation heats the plate, which heats the air in the collector. A fan or ventilator draws air from the room through a collector and pushes it back into the room. Roof-mounted collectors require ducts to move air between the room and the collector. The wall collector is placed directly on the south-facing wall and a hole is drilled in the wall for the collector’s air inlet and outlet.

A simple “window box tie” fits into an existing window opening. They can be active (with fans) or passive. In the passive type, the air enters the bottom of the collector and rises when heated into the room. The deflector or flap prevents the air in the room from flowing back into the cladding (reflector) when the sun is not shining. These systems provide a small amount of heat due to the relatively small collector area.

Breathable air collector

Breathing air collectors use simple techniques to heat solar heat and buildings. The collector consists of a dark perforated metal plate attached to the south wall of the building. Space is created between the old wall and the new façade. The dark outer wall absorbs solar energy and warms up quickly on sunny days, even if the outside air is cold.

A ventilator or ventilator draws ventilation air into the building through a small hole in the collector and an air gap between the collector and the south wall. The solar energy absorbed by the collector heats the air flowing through the collector up to 40 ° F. In contrast to other heating technologies, breathable air collectors do not require expensive glass.

Breathing air collectors are generally not suitable for today’s closed homes, as they are ideal for large buildings with high ventilation loads. However, you can use a small breathing air collector to preheat the air flowing through the heat recovery fan or heat the air coil of the air heat-source heat pump to improve efficiency and comfort on cold days. However, there is currently no information on the cost-effectiveness of using such a breathable air collector.

Economic Aspects and Other Benefits of Active Solar Heating

Active Solar Heating systems are cheaper in cold climates with excellent solar resources when replacing more expensive heating fuels such as electricity, propane, and oil. Some states offer sales tax exemptions, income tax deductions or deductions, and property tax exemptions or deductions for PV systems.

 The cost of Active Solar Heating varies. Commercial collectors are guaranteed for over 10 years and should easily last for decades. The efficiency of the active heating system is improved by heating household water as well. Otherwise, inactive collectors can heat the water in the summer.

Warming your home with Active Solar Heating can significantly reduce your winter fuel costs. Solar heating systems also reduce air pollution and greenhouse gases caused by heating or generating electricity using fossil fuels.

Solar system selection and dimensions

The choice of the right solar system depends on factors such as the size of the house, the design, and the heating needs. Local alliances may limit your choices. For example, the Homeowners Association may not allow solar panels to be installed on certain parts of a home (although many homeowners could challenge such placement).

The climate of the area, the type and efficiency of collectors, and the collector area determine the amount of heat a solar system can provide. It is usually cheaper to design an Active Solar Heating that covers 40% to 80% of your home heating needs.

Systems that provide less than 40% of the heat in a house are rarely cheap unless solar panels heat the room or two and are used in heating equipment that does not require heat storage. Well-designed insulated homes with passive solar heating technology require small, inexpensive heating systems of all kinds and require very little additional heat other than solar.

In addition to the fact that designing an Active Solar Heating that provides enough heat 100% of the time is generally not practical or cheap, most building codes and mortgage lenders require a backup heating system. Auxiliary or backup systems provide heat when the solar system cannot meet the heating needs. Backups range from wood stoves to traditional central heating.

Control of the solar thermal system

Controlling a solar heating system is generally more complex than a traditional heating system because it analyzes multiple signals and controls multiple devices (including traditional backup heating systems). Solar Control uses sensors, switches, and motors to operate the system. The system uses other controls to prevent the collector from freezing and extremely hot.

At the heart of the control system is a differential thermostat that measures the temperature difference between the collector and the storage tank. If the collector is 5.6 to 11 ° C (10 to 20 ° F) warmer than the storage unit, the thermostat turns on the pump or fan to circulate water or air through the collector and storage media or home to heat it.

The operation, performance, and cost of these controls are different. Some control systems monitor the temperature of different parts of the system to see how the system works. State-of-the-art systems use microprocessors to control and optimize heat transfer and heat transfer to the warehouse and home areas.

Solar panels can be used to operate low voltage fans, direct current (for air collectors), or pumps (for liquid collectors). The output of the solar module corresponds to the solar heat gain available to the solar collector. With careful sizing, the speed of the fan or pump is optimized for efficient solar radiation in the working medium. When the sun is in poor condition, the fan or pump is slow and runs fast during the high gains of the sun.


Individual control may not be required when used with a room air distributor. This ensures that the system will function in the event of a power outage. Battery PV systems can also provide power to run a central heating system, which is expensive for large systems.


Building Standards Laws, Agreements, and Regulations for Photovoltaic Power Generation Systems

Before installing a solar system, you should review local building regulations, zone ordinances, parcel contracts, and special location regulations. Building permits may be required to install solar systems in existing buildings.

Not all municipalities or municipalities first welcome renewable energy systems in residential areas. This is often due to the ignorance or relatively new nature of renewable energy systems, but the installation of the system requires following existing construction and approval procedures.

Building codes and zone compliance issues for solar system installations are usually regional issues. Even if there is a state-wide building code, it usually applies by city, county, or township. Here are some common problems homeowners have encountered with building codes:

  • Exceed the load on the roof
  • Unacceptable heat exchanger
  • Improper wiring
  • Illegal manipulation of drinking water supply.

The possible zoning issues are

  • Closed courtyard
  • Establish an illegal roof overhang
  • The system placement is too close to the boundaries of streets and parcels.

Special regional regulations such as B. Local community, parcel, or homeowner association rules must also be complied with. These practices, historic district regulations, and floodplain regulations are often overlooked. Contact the building and enforcement departments of your area’s jurisdiction and the appropriate homeowner, parcel, neighborhood, and/or community association to find out what is required to comply with local regulations.

Installation and maintenance of the solar system

The performance of an active PV system depends on the location, design, installation, and quality, and durability of the components. Although today’s manifolds and controls are of high quality, finding an experienced contractor who can properly design and install the system can still be difficult.

After you install your system, you need to maintain it properly to optimize performance and avoid failures. Different systems require different types of maintenance. You also need to set up a calendar that lists the maintenance tasks recommended by the component manufacturer and the installer for installation.

Most solar water heaters are covered by homeowners insurance. However, frostbite is generally not the case. Check with your insurance company for applicable insurance policies. Even if your provider has your system, it’s best to let them know in writing that you have a new system.

Difference between the active solar system and passive solar system

Understanding the difference between active and passive solar systems can be a hassle at times. We have identified the major differences between them, the capabilities of both systems, and the overall performance.

Both can convert solar energy into electricity, but they perform the same function, but with slightly different configurations and performance. We have listed some of the pros and cons of both solar systems.

Active solar system

Active solar systems use hot water pumps or fans to pump liquid. One of the main advantages of their use is that they can be used to increase the effectiveness of the solar system. Active solar modules rely only on external energy sources. We have listed some characteristics of active solar systems that you can see:

The positive side of the active solar system

  • The main building material is a flat panel photovoltaic module. This type of panel uses an advanced design formed by joining all the panels together.
  • A common method is to use liquid or air as the conductor for the solar collector. Solar panels are primarily used for energy storage and conduction.
  • Conductors that use fluids are commonly known as hot water manifolds. Those that use air are called air collectors.
  • Liquid conductors are more commonly used than air conductors. The air duct has only one drawback, but it does not freeze.Positives of Active Solar Systems (1)

Negatives of Active Solar Systems

Like other products, active solar systems have some drawbacks. Let’s take a look at each of them:

  • The equipment you need is expensive.
  • Device maintenance can also put a lot of strain on your pocket.
  • The liquid that stores heat in the solar panel can release toxins into the air.

Passive solar system

Passive solar panels rely heavily on home design, construction, and construction. PS systems use solar energy for heating and cooling. Passive solar systems work without external devices. They use a passive collector to convert light rays into the sunlight.

Passive collectors are based on the laws of thermodynamics, which transfer heat from the hottest surface to the coldest surface. The overall success of a passive solar system depends on its general orientation and the thermal mass of the wall. Investing in passive solar systems is an interesting idea if you are trying to power a small business or facility. The passive solar system is independent of all external devices.

Solar panels capture the sun’s rays through glass windows that absorb and store heat. The passive solar system includes the following features.Passive solar system

Positives of Passive Solar Systems

  • No external device is required, so the entire setup is automatically economical.
  • In the end, all energy costs were reduced by 14%
  • It is good for your health as it does not cause allergies or dry mucous membranes.

Disadvantages of passive solar systems:

  • Efficiency is directly time-dependent. Buildings can overheat, especially if you live in a hot area.
  • Efficiency depends directly on weather conditions. Buildings can overheat, especially if you live in a hot area.
  • For maximum success, you need to choose the right type of window.


PV system

 A PV system is like any other electromechanical system. The materials used may differ from those used in electromechanical systems, but the operating and interfering systems remain the same.

Photovoltaic panels are used to generate energy when exposed to sunlight. Other specific components are DC-AC inverters, battery banks, systems, battery regulators, and specified electrical loads.

Which solar system to choose

Weigh all the strengths and weaknesses before proceeding to the final step. Make sure you make your final decision based on the amount of sunlight you receive.

We have described all the pros and cons of both types of solar panels. It’s time to make sure you choose the right type and your decisions are calculated and well thought out.

We hope you enjoyed this article. Active Solar Heating | Difference Between Active and Passive Solar System

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