The Best Methods of Harvesting Solar Energy: Direct and Indirect Ways!

methods of harvesting solar energy

As efficient as fossil fuels are in generating large amounts of electricity in a single area, they are also limited in nature and environmentally toxic.

This is why scientists have directed their focus toward sustainable energy sources like hydropower, biomass energy, geothermal, wind energy, and solar energy.

Among these sources, solar energy is the most inexhaustible means of harvesting energy because the sun’s light can be converted to heat and electricity directly.

In this guide, we explore all the different methods of harvesting solar energy!

Primary Methods of Harvesting Solar Energy

Solar energy power plant

If you’re interested in solar energy, chances are you’ve seen your share of solar panels deployed on rooftops and solar farms. While they are an impressive unit, they only constitute one source of harvesting solar energy.

Here is a detailed list of the ways you can enjoy clean energy and save hundreds on your electric bill:

Photovoltaic Solar Panels

Photovoltaic (PV) solar panels are the most common form of harvesting solar energy. PV solar panels are used everywhere — in schools, homes, offices, industries, and hospitals — to generate electricity directly from sunlight and power outlets and appliances.

Dozens of PV cells combine to form one photovoltaic solar panel. Each cell is engineered with two semiconductors that connect to make a depletion zone.

This zone is disrupted as soon as sunlight hits the panel and passes through the semiconductors. The disruption is what generates direct current electricity (DC).

Since residential spaces run on alternating current power, the DC electricity needs to be inverted to be of use. This is where an inverter comes in, connects with the panels, converts DC power into AC, and completes the PV apparatus.

Thermal Energy Solar Panels

The sun is, essentially, a huge ball of electromagnetic radiation. When sunlight hits Earth, this thermal energy is converted into heat and absorbed by dark-colored objects — which is why wearing black on a sunny day will make you sweat more.

Solar scientists have used this process to engineer thermal energy solar panels and thermosiphons that generate power and heat spaces using dark-colored plates and systems.

Solar Water Heaters

In addition to lowering electricity bills, harvesting solar energy can also decrease water bills. Conventional water heaters, or geysers, run on thermal energy, which is produced by natural gas or electrical power.

Once it was discovered that solar power can generate thermal energy directly, solar water heaters were developed. They’re designed using thermal solar panels and connected with pipes to heat the water circulating throughout the space.

These solar water heaters are perfect for homes and commercial spaces residing in sunny climates. Don’t worry, you’ll still be able to enjoy cold water when needed.

Evacuated Tube Solar Water Heater

Vacuum tubes or non-concentrating collectors are a step above a simple solar water heater. These not only maximize the efficiency of generating energy, but they also minimize heat loss.

The apparatus is made up of cylindrical glass tubes, dark in color, that act as a vacuum. Unlike a simple panel, the cylinder shape allows solar energy to be absorbed from all sides and at every point in the day. So, little heat is lost and most of it is absorbed.

The glass tube covers a thin copper wire that collects the thermal energy and heats water stored in the connected tank using heat transfer fluid.

While solar water heaters are perfect for sunny climates, evac solar water heaters are designed to work in harsh winters.

Molten Salt Solar Plants

Also known as concentrated solar panels, molten salt solar plants are used to drive huge turbines and store large amounts of electricity in reserve. This helps solar farms and industrial spaces run efficiently during cloud cover or at night.

Large parabolic panels or heliostat mirrors collect solar energy throughout the day and transfer it to an insulated tank containing molten salt (a liquid). This heated system, then, runs the industry when the sun is hidden away.

Alternative Ways to Harvest Solar Energy

A solar home

The five methods above outline the direct ways of converting solar energy into electricity. Since commercial power runs on a much larger scale, indirect ways of harvesting solar energy have also been engineered.

These methods convert solar energy into heat energy (instead of electricity) which is subsequently used for various purposes.

Here is a basic rundown of the indirect methods available and their applications:

Concentrating Solar Collectors

Also known as a CSP, this system generates solar power by concentrating the sun’s thermal energy into a host of mirrors or lenses.

This way they can develop more heat than PV, have greater energy conversion efficiency, and have enough thermal capacity to generate power even after the sun has set or when there is a cloud cover.

Point Focus Collectors

Made of huge parabolic solar dishes or panels, point focus collectors concentrate the sun’s energy into one single point.

Large parabolic dishes are layered on top with reflective material and they move with the sun across the sky all day. So, to be of any value in generating solar energy, they must constantly keep track of and be in line with the sun.

This apparatus can be deployed as a single dish on the rooftop or paired with multiple parabolic dishes to make an array and generate ten times more energy from the sun.

Line Focus Collectors

Also known as parabolic troughs, line focus collectors are also made with large dishes that focus the sun’s energy into a single point.

This apparatus is far more high-powered than the point focus collectors. The parabolic panels are situated like a long trough and layered with a highly reflective material. They pivot throughout the day, tracking the sun to collect maximum sunlight.

In the center of the trough, a water pipe is attached which is heated directly by the solar radiation converted by the reflective dishes. This heated water produces a lot of steam that helps run a power plant.

Applications of Concentrating Solar Collectors

CSP collectors can produce a large amount of power efficiently and operate with little maintenance needed so they are used in a wide variety of commercial applications — primarily at an industrial scale.

  • They have enough energy to power Stirling engines
  • They can drive a turbine and generate electrical power using steam
  • They help the food industry process edible materials faster using the solar heat
  • Water can be desalinated easily with the help of parabolic solar dishes
  • Concentrated solar panels can also be used within power plants operating fossil fuels and help cut down toxic carbon emissions
  • CSP collectors enhance oil recovery as well

Non-Concentrating Solar Collectors

Ideal for residential purposes, non-concentrating solar collectors have been engineered with an interceptor the same size as the absorber of sunlight.

Flat Plate

A flat plate solar collector is a box-like apparatus made of a metal plate — usually aluminum or copper — that focuses and absorbs solar energy.

Between the interceptor and the absorber is a transparent cover or a glaze that lets in solar radiation and helps heat the dark absorber plate. Flat plate panels are best known for collecting both diffused and beam radiation.

The cold water or air present in between the absorber and the glaze heats up and generates power. The side panels are most often insulated to cut down on heat loss.

These are usually used in homes because they are easy to manufacture plus they are easy on the pocket.

Applications of Non-Concentrating Solar Collectors

Other than flat plate collectors, evacuated tube collectors also come under non-concentrating solar collectors. They are smaller in size compared to the large parabolic dishes, and easier to operate, so they can be used on a smaller scale.

  • These thermal collectors are used to heat swimming pools
  • Hot tubs, baths tubs and water for showers can be heated up using N-CSP
  • Flat plate collectors are great at space heating
  • They are perfect for domestic water heating
  • Flat plate thermal collectors work great throughout the year in heating water

Frequently Asked Questions

What is the difference between concentrated solar and photovoltaic solar panels?

A concentrated solar panel uses the sun’s energy to run a heat engine that produces electricity. A photovoltaic solar panel utilizes the light of the sun (not its energy) and converts it directly to electricity.

Is CSP more expensive than PV solar panels?

Yes, CSP (concentrated solar panels) are more expensive than PV solar panels (photovoltaic solar panels). This is one reason why investors and energy enthusiasts are more inclined toward installing a PV solar panel.

Final Thoughts

Now that you have a clearer idea of what the best methods of harvesting solar energy are, you are one step closer to living a sustainable and eco-friendly life.


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