It turns out that solar energy can be used in both active and passive ways. Let’s make a brief comparison of these technologies.
Active solar energy systems
Let’s start by looking at active solar energy systems. When we use the term “active,” we mean any system that uses special appliances, electronic controls or other intelligent systems.
From familiar examples:
- Solar panels. Each is made up of silicon cells. When light hits their surface, an electric current is generated through the photovoltaic effect. The collected energy can be stored in batteries and used to power electrical appliances in the house.
- Solar collectors. The principle of their work is reduced to the fact that the solar energy heats the liquid inside the collector, thus creating thermal energy. It can be used to heat water for household needs and heating.
“Active” such systems makes the need to use a large amount of equipment to benefit from solar energy.
In the case of solar panels, you also need batteries, a controller, an inverter, fasteners and many other small things.
Collectors have a big system, too:
- The panels themselves.
- The control unit.
- The storage tank.
- Heat exchanger, etc.
Passive solar energy systems
The key difference here is that passive systems do not use special devices, electronics or other controls. Instead, such systems work solely through the natural absorption of solar radiation by the thermal mass. The term “thermal (thermal) mass” refers to any material that can absorb heat. Here are some good examples of such materials:
So how does passive solar energy work? The whole secret is in a properly designed building, where materials with thermal mass will be competently applied.
Important in such buildings are large windows facing south, so that as much light as possible can penetrate inside.
The principle is that such a house accumulates solar thermal energy in order to release it later. At the same time, no additional equipment is needed for this.
Pros and cons of the active use of solar energy
- It helps reduce carbon dioxide emissions.
- You can save on utility bills.
- Active solar power is more efficient than passive solar power.
- Solar panels and collectors are always more powerful than passive technology.
- You can always upgrade the system to increase efficiency.
- Solar panels and collectors are expensive.
- Such systems take up space outside and inside the home.
- Active systems require maintenance, equipment replacement.
- Installation requires a secure roof and no shadows falling on it.
Pros and cons of passive solar energy
- Pluses for the environment, because you can save on electric heating and ventilation.
- The construction of a passive house does not cost much more than a conventional one.
- You can save money on utilities.
- Nothing ever breaks or breaks down.
- You don’t need to service any equipment.
- The building will look the way you want it to look without the need for different appliances to be installed on it.
- It’s not as efficient as solar collectors.
- You won’t be able to completely eliminate utilities, only save a little money.
- All the nuances need to be considered during the design and construction of the building.
- It may be necessary to cut down trees and other vegetation, so that a sufficient amount of sunlight enters the windows.
So, the difference between active and passive solar systems:
- Active ones use special equipment that directly converts solar energy into heat or electricity. A passive system is already part of the house, or rather the house itself.
- Active systems are always more efficient than passive systems and allow you to completely eliminate some utilities. With passive ones, you can only save a little money.
Some homes have both active and passive systems. Using this approach makes a home completely carbon-neutral.