Solar 101

Greetings from a blazing hot Minneapolis and Massachusetts!

Like many other parts of the country, this past week has seen incredibly high temperatures in Minnesota, with the temperature reaching the 90s in almost the entire state. And it's only early June! While the high temperatures have been uncomfortable, the near constant sun has guaranteed one thing: a plethora of solar energy! In this second issue of ClimateRoots, we are diving into Solar Energy 101, focusing specifically on photovoltaic solar, since it is the most common type of solar energy in the United States.

Solar energy is created by capturing the light emitted from the sun- also known as electromagnetic radiation- and converting it into energy (“How Does Solar Work?”) It is important to note that light, while it acts like an electromagnetic wave, is actually made up of Photons, or particles of light. The two main types of solar energy technologies in the United States, photovoltaic solar (PV) and concentrated solar thermal power (CSP), take advantage of these properties of light.

Even if you don’t know it, most of us are familiar with solar PV, since these types of solar panels are the ones we often see on buildings, homes, or fields. However, you are less likely to know how these panels convert sunlight to electricity or how that energy eventually reaches our homes. The solar to energy conversion takes place in what is called a PV cell. It is these cells that give solar panels their grid-like appearance. Made of semiconductive material, most often Crystalline Silicon, the cells are strung together underneath glass or plastic to form the panel itself. (“How Do Solar Panels Work?”)

This part is a little nitty gritty but bare with me. PV cells are composed of two layers, a Boron doped P-type layer which has a positive charge, and a phosphorus doped N-type layer which has a negative charge. When sunlight hits the PV cells, the Photons strike the N-type layer and transfer their energy to the electrons in the PV cell. With this additional energy from the Photons, the electrons can now flow through the solar cell toward the P-type layer. This movement of electrons in a specific direction (from N-type to P-type layer) creates an electric current. (“How Do Solar Panels Work?”).

The electric current is then collected by wiring and is routed through an inverter where it is converted from a direct current (DC) to an alternating current (AC). This allows the energy to be integrated into the electric grid (“PV Cells 101”). For more information on the electric grid, check out our first ClimateRoots issue here.

If molecular talk bores you, here is a general overview of the entire PV solar process:

Sunlight hits the PV cells and energy is absorbed
An electric current is formed within each PV cell
The current travels toward an inverter, which converts the current from direct current (DC) to an alternating current (AC)
The AC electricity is used on site or diverted into the electrical grid

As a renewable energy resource, solar power has incredible potential. According to the Office of Energy Efficiency & Renewable Energy, “The amount of sunlight that strikes the earth's surface in an hour and a half is enough to handle the entire world's energy consumption for a full year.” Just think of how much energy could be produced if every home in the US utilized solar power, or every single building for that matter! Unlike fossil fuels, the sun provides unlimited energy that can be harnessed and distributed throughout our electrical grid without the heavy emissions.

In our next issue, we will be diving into community solar, and breaking down how you can tap into it in your neighborhood.

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Solar 101

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