Solar power 101: What is solar energy?

Solar energy is the most abundant energy resource on Earth. Each day, it’s harvested as electricity or heat, fueling homes, businesses, and utilities with clean, emission-free power. As the world pivots towards sustainable energy solutions, solar power is crucial in shaping our global energy landscape. But how does it work, exactly?

Our sun generates an infinite amount of power. Solar energy technologies capture and convert that power into electricity that we can use in our homes and businesses. If you’ve found EnergySage, you probably already know that solar panels are one way to harness the power of the sun. But they aren’t the only way. Solar panels, also known as photovoltaics, capture energy from sunlight, while solar thermal systems use the heat from solar radiation for heating, cooling, and large-scale electrical generation. 

Let’s explore these mechanisms, delve into solar’s broad range of applications, and examine how the industry has grown in recent years.

Solar energy comes from the limitless power source that is the sun. It is a clean, inexpensive, renewable resource that can be harnessed virtually everywhere. Any point where sunlight hits the Earth's surface has the potential to generate solar power. 

Unlike fossil fuels, solar power is renewable

Solar power is renewable by nature. Sunlight is infinite, and enough solar radiation hits the planet's surface each hour to theoretically fill our global energy needs for nearly a year. No matter how much solar power we use to generate electricity, the sun will continue to shine. It doesn’t deplete. 

In contrast, oil, gas, and coal took hundreds of thousands of years to form. Every time we burn one of those resources to create electricity (and emissions), that finite resource moves marginally closer to depletion.

Our sun is basically a massive nuclear reactor. Deep in the Sun’s core, nuclear fusion reactions produce huge amounts of energy that radiate outward from the sun’s surface and into space in the form of light and heat.

We harness and convert solar power from the sun into usable energy using photovoltaics (more commonly known as solar panels) or solar thermal collectors. 

How solar panels work

Each particle of sunlight contains energy that fuels our planet, but to power your home, it has to be captured and converted into what we call “usable electricity.” Solar panel systems do precisely that. 

Solar panels capture sunlight through a process known as the photovoltaic effect (this is why they’re also called photovoltaics or PVs). Technically speaking, the photovoltaic effect is a property of specific materials called semiconductors (nonmetals with conductive properties) that create an electric current when exposed to sunlight. In other words, the materials used to make solar panels enable them to generate electricity when the sun shines on them. 

Solar panels consist of a layer of silicon cells, a metal frame, a glass casing unit, and wiring to transfer electric current from the silicon. Here’s how a solar panel system works:

• When sunlight strikes the silicon solar cells, it knocks electrons loose, setting them in motion and creating a flow of electric current. 

• Wires then capture this direct current (DC) electricity and feed it to a solar inverter. 

• The solar inverter converts it to alternating current (AC) electricity, which most U.S. electric grid and household appliances use.

When you think about solar power, you probably imagine solar panels. As we mentioned, solar panels convert sunlight into electricity that you can use immediately or store in a solar battery. Solar panels generate electricity for residential, commercial, and utility-scale applications.  

Types of solar panel systems

Solar panels are the face of solar power, but solar thermal energy can actually be more efficient. This type of solar energy directly captures heat from solar radiation and uses it for several applications. There are three general types of solar thermal energy: low-temperature used for heating and cooling, mid-temperature used for heating water, and high-temperature used for electrical power generation.

Solar thermal energy has a broader range of uses than a photovoltaic system, but using it for electricity generation at small scales isn’t as practical as using photovoltaics.

Solar is one of the fastest-growing energy sources in the world. The rapid development of solar power nationwide and globally has also led to parallel growth in several adjacent areas. Solar battery systems, electric vehicles, and heat pumps are all sectors likely to explode, amplifying the benefits of solar. Here are some quick facts about the industry’s growth:

• Solar capacity grew about 25% annually over the past decade. 

• To date, the United States has about 137.5 gigawatts (GW) of installed solar power capacity—enough to provide clean energy to about 25 million homes.

• As of IREC's most recent Solar Job Census covering 2022, the solar industry supported 263,883 jobs—a 3.5% increase from 2021.