Trying to find renewable ways to power the energy-consuming society that we live in is a difficult task. In recent years, solar panels have been used to create electricity from sunlight, but the process of converting sunlight into electricity is not very efficient.
For this reason, there is more than one method to gain energy from the sun and in some cases work a certain method may work better or efficiently than others when trying to accomplish a specific task bringing us to the following.
Solar thermal energy is the use of solar radiation, in the form of heat, to generate power or to accomplish a need that benefits us as humans for example heating water. To do exactly that we use Collectors.
Many different types of collectors can be used to harvest this energy. Some are more efficient than others and work better in certain climates than others. Let us delve further into the different types of collectors so that we may know exactly what they are and how they work best and for what cases.
What is a Solar Collector?
The main difference between a solar panel and solar collectors is that collectors collect solar energy and convert it to a usable form of energy whereas a panel converts the light directly into electricity with little to no conversion.
A solar collector is a device that absorbs the energy from the sun and uses it to heat a fluid, often water. They are used for heating homes, buildings and water, or any type of fluid that may meet your requirement.
A Solar Collector is very closely related to solar thermal energy and many of these devices are used to harvest this form of energy. However, they can also be used to provide hot air which may be required in chemical processes such as drying crops.
How does a Solar Collector Work?
The process involves allowing the sun’s energy to heat the fluid and then passing it by a heat exchanger. The fluid is used to transfer its heat into another fluid such as hot water or steam. This in turn can be used for heating buildings, water or any other requirement.
There are different types of collectors that work on the same principles but for different requirements. There are simple domestic types available that can heat your water easily but there are also industrial ones that can meet very large requirements.
Collectors do not require much maintenance either so it won’t cost you a lot to keep them operational over time. Although it should be noted that some collectors require special coverings if left outside during the wintertime to prevent freezing.
Types of Solar Collectors and their Functions
There are four main types of solar collectors and they are as follows:
1. Flat Plate Collectors:
Flat Plate Collectors are metal boxes with a glazed top through which sunlight enters. Inside the box, they commonly have glazing which is set on a flat absorber plate that absorbs solar radiation and converts it to heat energy. There is usually air or low-pressure water inside of the collector.
Flat Plate Collectors are very efficient in warmer climates and the glazing is usually made of tempered glass and the absorber plate is made of copper/aluminum. They are most often used in areas where there is little to no snowfall in the wintertime. They can be placed directly on roofs like they are commercial systems.
A unique fact about these types of systems is that they can be used to heat water directly without the need of a storage tank. A flat plate collector can provide hot water up to about 80 degrees Celsius (176 Fahrenheit).
2. Evacuated Tube Collectors
This type of solar collector uses a series of glass tubes that are vacuum-sealed. Inside the tubes are metal absorber plates that are used to soak up solar radiation. These tube collectors are typically black or dark grey in color to absorb as much energy as possible and are connected to a heat pipe with the fluid inside is kept at a certain pressure with a hot end and a cool end to raise the temperature higher than flat plate connectors. This in turn is used to heat water or air.
Evacuated Tube Collectors have an advantage over flat plate ones because they can be used for heating water even when it is very cold outside. This means the collector will not freeze over which allows you to collect heat all year long by draining off any liquid produced during this time. They can reach high temperatures of 170°F (77°C) to 350°F (177°C), and under the proper conditions and can be quite effective.
3. Line Focus Collectors
This type of solar collector uses four to eight line focus parabolic troughs that are connected together with a manifold. They can be adjusted and moved electronically to follow the path of the sun which allows maximum exposure at all times and lessens shadows cast on the absorber plates.
Line Focus Collectors consist of two long tubes located parallel to each other. The first one is where fluid enters and starts its journey through each tube until it reaches the end where it exits as steam or heated water, depending on your requirements. A Line Focus Collector has a simple design but is quite effective as it can reach very high temperatures due to having multiple collectors that range from 80°F (26°C) up to 450°F (232°C). It has multiple applications including the heating of water, air conditioning or even generating electricity in Solar thermal power plants.
4. Point Focus Collectors
This type of solar collector uses a parabolic dish that is mounted on an adjustable stand. It usually consists of 3 to 6 individual dishes that are made of metal which are automatically repositioned by motors in order to focus the sun’s energy at its focal point where it converts solar radiation into heat energy.
Point Focus Collectors can operate even when there are some clouds present because they have automated alignment systems that make them more efficient than other types of collectors.
These disheveled-looking solar collectors are the most effective type of solar collector, with an average temperature between 400°F (204°C) to 650°F (340°C). Point Focus Collectors are especially good for generating electricity in Solar Thermal Power Stations.
As you can see there are many different types of solar collectors and each one has its own individual purpose. That is why it is important to keep in mind what your requirements are as far as heat generation goes and then decide which type would work best for you depending on geographical location. Once you know this, you will be able to choose the correct system that will maximize energy collection while minimizing costs.