With more than 126 gigawatts, the U.S has enough solar installed to power 22 million homes. The State of California accounts for most of that capacity at 39%. But what is solar energy and why is there so much investment into it compared to coal or gas?
Solar is energy produced by the sun. The sun is a giant nuclear fusion reactor that produces energy through a proton-proton chain reaction. Protons of hydrogen atoms collide and fuse in the sun’s core to produce helium atoms. Fusion through this PP reaction releases huge amounts of energy as waves and particles.
The energy, light, and heat spread out into our solar system as electromagnetic radiation. The sun, however, isn’t the only star that produces energy through a PP reaction. Other stars of similar size to our sun also experience the same nuclear fusion and spread electromagnetic radiation through their solar systems!
The electromagnetic spectrum consists of waves of different frequencies and wavelengths, most of which are invisible to us. High-frequency waves include gamma rays, x-rays, and ultraviolet radiation (UV). Most of the heat we get from the sun is low-frequency infrared radiation.
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The visible spectrum is between infrared and UV. It contains all the colors you see with red being closer to infrared and having the longest wavelength. Violet has the shortest wavelength and is closer to UV.
The energy takes less than eight minutes to reach the earth. It is the sustenance of all life on earth and it is absorbed naturally or harnessed through man-made technology. Source
There are at least four different ways in which we absorb and harness solar energy. Let’s take a look at what they are and how they work.
What Are The 4 Main Types Of Solar Energy?
Passive solar heating is a natural form of solar energy. Photovoltaics, solar water heating, and concentrated solar are man-made forms of solar energy. They are man-made in that they use machines to harness solar energy.
Passive solar heating
Passive heating is a relatively less known or overlooked form of solar energy. Yet it’s the simplest and most abundant. Also called solar gain or daylighting, it is the energy absorbed by buildings or animals and of course humans.
Building a skylight or painting a water tank black so it can absorb more sun is putting passive solar heating into use. Passive solar heating can be used to design a more energy-efficient home. One great example is a cool roof or painting a roof a bright color to reflect heat and keep the home cooler.
Solar water heating
Solar water heating is a more active way of using heat energy from the sun. Also known as solar thermal energy, it is most recognizable in the form of solar collectors or tubes that heat water.
The working principle of a solar collector is that they absorb the heat from the sun and then transfers the heat to give you hot water.
Concentrated solar power
Concentrated solar uses a similar principle to solar water heating. Heat is collected by way of mirrors and concentrated onto a central tower or tubes with water.
The difference here, however, is that the water is not used directly. Instead, the steam from the water is used to turn massive turbines that generate electricity.
Photovoltaics is the use of solar panels to generate electricity. It is different from the other types of solar energy in that instead of using heat from the sun, it uses light to produce electricity. This happens by way of the photovoltaic effect.
A solar panel is made from silicon. The silicon is injected with impurities like phosphorous to give it more electrons and make it more conductive. Light from the sun contains particles of energy known as photons.
When a solar panel is exposed to direct sunlight, it absorbs those photons. The photons energize the electrons in the solar panel creating a flow of electricity.
Photovoltaics are possibly the most important type of solar energy. This is because photovoltaics have the potential to provide quick access to electricity at a cheaper cost compared to traditional power generation methods. This is mainly why photovoltaics is the fastest growing area of solar.
Why Solar Energy Is The Best?
Solar is a cheap, clean source of renewable energy compared to electricity. In the U.S, solar panels offset about 100 million tons of carbon emissions per year. This is equivalent to planting 131 million acres of forest. Electricity generated from fossil fuels like natural gas, coal, and oil contributes a quarter of carbon dioxide emissions.
Carbon emissions are linked to climate change and global warming. Transportation and electricity generation makes up 52% of emissions with electricity generation contributing 25 percent. Switching to solar and relying less on fossil fuels can drastically reduce carbon emissions.
Aside from the environmental impact, solar has several other advantages. For one, it is a cheaper source of electricity. On average, homeowners save about $1,500 per year by switching to solar. Considering that homeowners spend almost the same amount on electricity this means you can completely offset your electricity bill when you go solar! Source
Another important advantage of solar is its potential to provide communities without grid connections with access to electricity. Over 900 million people around the world don’t have electricity and still rely on wood and kerosene for heat and lighting.
What Is The Biggest Problem With Solar Energy?
The biggest problem with solar is it is dependent on how much available sunlight there is. Solar energy is intermittent. On cloudy or rainy days, the output from solar panels drops to almost zero. Also, the sun does not shine at night which limits the use of solar energy to daytime in the absence of energy storage.
The other main problem with solar is it is expensive. A solar system for an average home in the U.S can cost anywhere between 10,000 to $30,000. While the cost of solar has dropped over 70% since 2010 due to cheaper solar panels it remains prohibitively expensive for many.