What is a Solar Collector – A Detailed Guide

You must have heard about solar panels if you’re a fan of solar energy since it’s clean. But have you heard the term ‘Solar collector’? Do you know it’s as practical a model as solar panels are? Do you know how it functions? 

Let us help:

A Solar collector is a device used to collect heat from sunlight. That heat can be used for:

1. Cooking food and boiling water
2. Generating electricity

Solar energy collectors have had their presence since the 19th century. Their use isn’t a new concept, except that with advancements in technology, they’ve become better.

Solar panels are excellent for generating electricity for both domestic and commercial purposes. They use light to produce electricity, not heat. Whereas, a solar collector uses heat, not light. 

That’s the difference between the two despite both being powered by the Sun.

Intrigued? Want to learn more about solar energy collectors: their function, types, and application? Dive in and you’ll have all the answers. 

What are the Types of Solar Collectors?

Are all solar energy collectors suitable for domestic application? Well, no!

Therefore, before you choose a solar collector, it is crucial to understand its types. Solar thermal collectors are broadly categorised into two types:

1. Non-concentrating collectors
2. Concentrating collectors

Both these types have one major difference. The interceptor of a non-concentrating collector is bigger than the absorber. While in the concentrating collector, both absorber and interceptor are of the same size.

3 crucial purposes that solar collectors can be used for

#1. Running Solar Ovens

Before photovoltaic cells came into play and helped convert sunlight into electricity, people used to cook food by absorbing heat from the solar collectors. 

A German physicist, Horace de Saussure manufactured the first-ever solar oven in 1767. The oven could work at about 230°F or 110°C. 

Even after centuries have passed since their discovery, solar ovens are still a very practical concept. 

Sadly, the majority of people now rely on either wood or other fossil fuels. Only if wood in rural areas can be replaced with solar ovens, deforestation will be easily tackled. 

Additionally, carbon emissions will drop down and air pollution will finally be controlled. 

#2. Running Water Heaters

Solar water heaters appear as small black panels mounted on a roof. They should not be confused with PV solar panels. 

Usually, just one or two collectors are enough to heat water, but many black collector tubes can also be configured if you want to heat large water bodies such as swimming pools. 

#3. Generating Electricity for Residential Use

Parabolic solar collectors can be used to generate electricity for residential use. These solar collectors look like a large satellite dish but they contain mirrors instead of antennae. 

They direct the sunlight toward a Stirling engine to generate electricity. These engines are very different from a thermal power plant in the sense that they release no steam and emit no greenhouse gases. 

Very little water is lost during the production of electricity. As these engines have few moving parts and there are no emissions, they can be safely installed on the roof or in the backyard. 

People can also store electricity so that there’s power if the grid is down. 

What are the Differences Between Solar Collectors and Solar Panels?

The points of difference between the two can be traced on the basis of the following two factors:

Working

A solar panel consists of photovoltaic cells. Solar panels can be installed for use in large photovoltaic systems so that electric energy can be generated and supplied for domestic and commercial use. 

On the other hand, a solar energy collector gathers heat by absorbing it directly from the sunlight. The collector carries out the conversion of sunlight into usable energy forms. 

Efficiency

The efficiency of solar panels can range between 11-19 (even 22) percent depending upon the module. It is measured by the total amount of sunlight that hits the panel directly. The sunlight falling on the panels is converted into electricity. 

The efficiency of solar panels also depends on the pitch or tilt of the roof, panel orientation, shadow-free area, and a lot more. 

On the other hand, the efficiency of solar collectors is measured to be around 75 percent i.e., when the fluid you’re trying to heat reaches 100°C. The exact figure depends upon the thermal efficiency of the collector. 

Typically, the efficiency is the ratio of the average heat output from the solar energy collector divided by the rate at which the sunlight strikes the surface.

Factors Affecting Solar Collectors’ Efficiency and Performance

There are many factors that account for the efficiency and performance of a solar collector. Let’s have a look at the most significant ones:  

• The total surface area 
• The total incident radiation that hits the surface 
• The collector’s tilt and orientation.

Apart from these factors, there are some other factors too that influence the efficiency of a solar energy collector: heat gain, conversion factor, and loss of heat via convection and conduction.

Did you know that solar collector models are also classified as low-temperature collectors, medium-temperature collectors, and high-temperature collectors?   

When it comes to heating large water bodies such as swimming pools, flat-plate low temperature solar collectors are used.

The medium-temperature collectors with flat-plates are the ones that are used for heating purposes in residential and commercial buildings. 

When it comes to electricity generation, it’s high-temperature collectors that are used.

Conclusion

It is high time that we acknowledge the benefits of using a solar collector just as much as we acknowledge the use of a solar system. 

Both types use the sun’s energy as fuel. Although rooftop solar panels are quite advanced, solar collectors are practical models too.

FAQs

Q. When is a solar collector called a parabolic apparatus?

Solar Collectors are called solar parabolic apparatus when the installation is complex. 

Q. What is the electric energy output of a solar panel?

It depends on the type of module. Monocrystalline modules have the highest efficiency.

Q. What are the main advantages of a solar energy collector?

Apart from the direct advantage like decreased emissions, there are some underrated but very important advantages. 

• Less dependence on electricity from the grid
• Lesser air pollution
• Lesser electricity bills

As a solar energy collector is close to the electricity demand source, the cost of transmission in the process of bringing the electricity to customers is negligible.