Image provided courtesy of Microsoft.
The process of producing electricity with a solar system is not really a great mystery. It’s actually a very simple process, and the real mystery is why the US isn’t using more of it. The purpose of this post is to provide a brief overview of how solar PV systems work. In essence, the light from the sun hits the panels, and the electrons in the solar cells become activated. What this means is that they start moving around a lot more and in doing so, they start bumping in to each other more frequently. The interaction of the electrons produces electricity in the form of friction.
A solar panel or module, is comprised of individual solar cells. A solar cell is primarily silicon with some circuitry. The more cells contained in a panel, the more energy it can produce. A string of panels makes up an array and multiple arrays comprise a solar PV system. A PV system (Photo-Voltaic) is different from a hot-water system which is used specifically to heat water. A Concentrated Solar Power system (CSP) uses mirrors to focus sunlight on water, causing it to boil producing steam, which is then used to generate electricity. However, the focus of this post is specifically on PV systems.
Solar PV systems are generally connected to the grid, but for people in more remote locations a battery back-up system is often more practical. There are two primary types of solar panels; mono-crystalline and polycrystalline. Without going into a lot of detail there are advantages and disadvantages to each.
Silicon is most often used in solar panels as the primary active material in a solar cell because it has unique chemical properties. A silicon atom (Si) is comprised of twelve electrons on three separate ‘shells’ or layers. The outermost ‘shell’ has four electrons that are highly reactive. The outer electron shell of a silicon atom is seeking reach of state of equilibrium by ‘sharing’ its electrons with other atoms. Conversely, those other atoms will share their electrons as well.
Image provided courtesy of Solar City.
Of course they’re always moving to begin with but the energy from the sun causes their rate of interaction to increase. By bumping in to each other more frequently they generate friction. This friction is a source of electrical energy. From there it’s just a matter of channeling the current through all the wiring to the inverter. The inverter converts the electricity from direct current to alternating currently because the electrical grid is not designed to handle direct current.
The transformed current flows to where the demand is the closest. Depending on the demand within the building, the current will go there first to satisfy any existing demand. In a grid tied system any excess current is supplied to the grid. If it’s an off-grid system then presumably there is a battery back-up system to store excess current generated by the system for later use.
Most solar systems are designed to meet the average load of the building they serve, but they are typically not over-sized. Over-sizing a system is not very economical and utility companies generally don’t approve them in the first place. Producing electricity from the sun is a very practical way to meet our electrical demand. Producing energy in the same location it is used is more efficient than transporting it over great distances.
For a more complete description of how solar produces energy please refer to the following article.
Thanks for reading.