solar-how-it-worksSo, just how do solar panels create electricity?

It’s no secret that solar panels are the result of many brilliant scientific and chemical minds. The technology is relatively simple relative to the rest of the scientific world, but most scientists believe it has huge potential.

Dr. Ronald Nohr, currently a professor at the University of Denver and former UN scientist, explained the technology behind solar panels to SolarChargedDriving.Com.

“Solar power is going to take off eventually,” he noted. “Is it going to happen tomorrow? Probably not. Is it going to happen 10 years from now? Maybe, but probably not. But in college students’ lifetimes, it might. The sun, with all of its solar flares, is a great source of energy.”

What PV means
Nohr explains the meaning of the technical term for solar panels: photovoltaic cells. “Photo” means “light,” and “voltaic” means “electricity,” so it is literally “light electricity.”

First there is the chemical makeup of the photovoltaic cells.

“What we do first is to take a silicon panel,” he said. “Remember, carbon is in the same chemical family as silicon, and this is essential.”

solar-side1Carbon and silicon are in what is called the 4A chemical family. Any chemical in this family has four electrons in its outermost level, or valence shell. Any of these electrons are free to form bonds with other nearby atoms, and thus they are very important.

Chemical reactions key for solar
Since 4A family atoms have four bondable electrons, they can join up with four other atoms around them. This creates room for a lot of potential chemical reactions.

“So, the solar panel is made up of silicon, but the key is that it has impurities in it,” Nohr said.

The impurities are added in order to encourage high chemical reactivity. Without any impurities, most of the silicon’s electrons are used, and thus they are unable to move about and to create electricity.

By adding impurities, typically phosphorus and boron, some of the electrons are able to break free and to move about. Any movement of free-floating electrons is considered an electrical current.

“We call [the different mixes of silicon and impurities] the N, negative, and P, positive, types because on one side, with the N type, we put in impurities that have a surplus of valence electrons, which creates a negative charge. On the other panel that is attached, we have impurities in that silicon that are electron deficient, creating a positive charge” said Nohr.

Second, there is the process that occurs when sunlight hits a solar panel.

lead-with-sun1Sun energy made into electricity
“When you put [the N and P type silicon] together and expose them to the sun, the question is: how do they work?” he said. “Sunlight falls on the N type, and the N type then releases electrons that ‘cross the wire’ of the junction. The sun kicks out electrons and makes holes. Those holes lead to more holes. The electrons then move from N to P.”

The movement of electrons from N (negative) to P (positive) creates an electrical current. This, ultimately, is where the solar cell gets its energy.

“They have to get that repulsive charge to build up, and once they have that, then we have action,” Nohr said. “Sun takes electrons out and then when they build up in the junction, as a one way valve, they move out.”

Photons and light energy
Photons from light energy further break apart atoms, sending more electrons over the junction and creating the current and (using the cell’s electric field), a voltage. Eventually, these two combined create power. This current movement, along with the cell’s voltage (which is a result of its built-in electric field or fields) defines the wattage that the cell can produce.

“Without the sun, you don’t kick electrons out, you don’t create a potential difference,” Nohr said.

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The final step is to place metal contacts on the top and bottom of the PV cell so that the current can be drawn off for external use.

Nohr commented on the simplicity of the solar cell invention and criticized its slow rise to popularity.

“That’s as simple as it can get,” he noted. “What a great invention, ehy? Why haven’t we done anything? Why have we spent so few research dollars on solar? I don’t know. Why aren’t we investing like we used to invest in research? The U.S. used to be the leader in research, but not now. Let’s hope that we can start investing more in solar research.”

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