Solar Energy Definition

Let’s begin with a general overview of solar power. The sun provides us with natural light during the day. In doing so, it sends individual particles of sunlight, known as photons, to the Earth. Each photon contains energy, and that energy fuels the Earth in various ways.

It might surprise you to learn that, during any given hour, the Earth receives enough solar energy that it could theoretically fulfill the entire planet’s energy needs for one full year. But where does all this solar power actually come from? Well, keep in mind that the sun is a star, and like any other star, it’s basically one big nuclear reactor.

There are nuclear fusion reactions happening in the sun’s core all the time, producing huge amounts of energy that radiate out into space in the form of light and heat. Large quantities of this solar radiation ultimately reach Earth’s surface. Solar power can be collected via a technology called photovoltaics, then it will change sunlight directly into electricity that can be used to supply power to a home or a business. Generally, solar power works by converting energy from the sun into power.

Solar energy currently represents a relatively small fragment of the global energy economy, yet it’s gaining in popularity, largely thanks to the falling prices of solar panel installation, combined with a growing desire among homeowners to reduce their utility bills and their carbon footprints.

Using Solar Power

Now let’s take a closer look at solar technologies and the process of harvesting and using energy from the sun. We already mentioned photovoltaics, which represents the most common method of harvesting solar energy. This approach is generally used for small-scale applications, such as portable solar generators or residential solar systems.

Another option, called solar thermal capture, is typically better suited to produce solar electricity on a larger scale. Here’s a quick breakdown of these two basic options for harvesting solar energy.
Harvesting Energy With Photovoltaics

This is the method you’re more likely to be familiar with, as it describes the way solar energy is harvested in residential settings. By installing solar energy systems made with photovoltaic cells, or PV cells, homeowners can collect energy from the sun, using solar panels positioned on their roofs that convert sunlight into energy.

An inverter turns that solar energy into an electrical current, which can be used to power household systems, appliances and connected devices. With some photovoltaic systems, any surplus electricity is funneled back into the power grid, resulting in a credit from the utility company; in turn, if the PV system does not create enough solar electricity to power the home, the homeowner may draw power from the main utility grid.

By contrast, some PV systems come equipped with a solar panel battery bank, which means surplus energy can be stored and used at a later date. There are a few types of solar panels, but most residential ones use what’s known as the photovoltaic effect. This process allows them to convert raw solar power into usable energy. Here’s a rough breakdown of how solar panels work:

The sun’s rays hit a semiconductor within a solar panel (usually made of silicon), which releases electrons. These electrons move through a conductor to produce an electric current.
The current produced by these wires is known as direct current, or DC; your house requires alternating current, or AC electricity. A component known as a solar inverter turns the DC power into AC power.
AC power is then fed into the primary circuit board, meaning it can power any of the outlets or connected appliances in the home. Surplus solar electricity may be stored in a battery to be used when the sun isn’t shining directly on the panels.

This is a basic description of how solar electricity works in a residential setting, enabling homeowners to control their electricity generation. The benefit is that you can reduce or even eliminate your reliance on utility companies, and thus, your monthly utility bills. Even more impactful, it allows you to lessen your reliance on fossil fuels and municipal power plants, which cuts down on environmental pollution.

Harvesting Energy With Solar Thermal

Another option for harvesting solar energy is to directly capture heat from the sun’s radiation. The solar thermal method actually has a much broader range of uses than the photovoltaic process. With that said, it’s not nearly as practical or as feasible to use the solar thermal method on a small scale, which is why residential solar systems use the PV method. There are three main kinds of solar thermal energy used in industry:

Low-temperature solar thermal energy is used to heat and cool the air.
Mid-temperature is used specifically for heating water.
High-temperature is used for generating electrical power.

So, to flesh those out a bit more: Low-temperature solar thermal methods are primarily used to heat or to cool the air, as a means of climate control like space heating or air conditioning.

Mid-temperature solar thermal methods capture the sun’s energy and transfer it to pipes, heating the water those pipes contain.

High-temperature solar thermal is used to generate electricity on a larger scale, such as in an electrical plant. This process actually revolves around a series of mirrors, which are positioned to catch the sunlight and reflect it onto a series of tubes.

These tubes contain liquids that are effective in capturing and holding heat energy. This heated liquid is then used to turn water into steam, turning turbines to produce electrical power. You can understand why this complex system is not a feasible option for individual homes, but it represents a very promising renewable energy source for large-scale use.

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