SOLAR ELECTRICITY BASICS
UNCERTAIN TIMES In the face of grave doubts regarding the stability of our energy supply, environmental and safety catastrophes from mining and oil exploitation, and rising electric costs, many questions and uncertainties exist about today’s energy landscape. Solar energy can provide electricity and heat domestically without depending on foreign sources.
SOLAR ENERGY RESOURCE IN THE UNITED STATES As solar energy becomes better known, more people are able to appreciate the value of solar energy as a solution to our energy needs. The amount of solar energy that hits the earth every day is more than enough to power our homes and businesses. In fact, a single solar array of 100 square miles in the Mojave Desert can generate enough electricity to power the entire United States. 100 miles squared might seem like a lot of space–and it is a lot of space in a highly-populated area like New Jersey. However, the number of rooftops in the United States adds up to much more than 100 miles squared. In fact, New Jersey has been aggressively tapping into its solar energy resource by encouraging property owners to install distributed electric generation on their rooftops and elsewhere on their property. They are currently the leading market for solar electricity in the United States. Incentives are also available in Missouri to help make solar electricity attractively affordable. Combined with historically low prices for equipment, there has never been a better time to go solar.
LIGHT – THE VISIBLE FORM OF SOLAR ENERGY Light is perhaps the most common form of energy. It’s certainly the best known. In order to draw energy from solar energy, it’s necessary to have an understanding of the nature of light and the mechanics of light.
Light is composed of photons. These are little particles of solar energy that actually exert pressure as they hit objects. It’s even possible to construct a “solar sail” and catch the “solar wind” of photons that flow outward from the sun to push a spacecraft just like a sailing ship. We’re not building spaceships, but this example serves to show that photons “push” on objects that they collide with. So, the basic idea to remember is that solar energy penetrates materials and collides with the molecules that the material is made of.
PHOTOVOLTAICS: SOLAR ENERGY TO ELECTRIC ENERGY If you remember chemistry from high school, you probably recall that materials are made of atoms (which stick together to make molecules, but we’re not as interested in the molecules in this solar energy discussion). For the purposes of solar energy, we’re interested in Atoms because they have zippy little things we call ELECTRONS. Turns out that the photons we mentioned above can crash into the electrons that are zipping around the atoms. And that’s the fundamental principle of the photovoltaic effect: a photon penetrates a material, bumps into an electron, and knocks the electron free so it’s no longer attached to its “parent” atom. In a photovoltaic material, there are two layers. The electrons in one layer are bumped by incoming photons so that they move to the second layer. If there’s a wire connecting the second layer back to the first layer, then the electrons are pushed along the wire and end up back where they started. That flow of electrons is what we call “electrical current”. 
You can think of a photovoltaic material as an electron pump driven by incoming solar energy, just like a water wheel will turn when water flows past one part of it. The photons push the electrons from one layer to the next one, and that creates the electron flow that we see as electricity. The physicists, by the way, will howl about this explanation, but this article isn’t meant for them–it’s meant for anyone who just wants to have a basic understanding of what happens inside a solar cell when solar energy hits it.
