Solar panels, also known as photovoltaic (PV) panels or arrays, are renewable energy sources that transform the energetic potential of visible light into usable electric power. But what, exactly, are PV panels, and how do they work?
How Do PV Arrays Work?
PV panels are composed of thousands of tiny devices called “solar cells” or “photovoltaic cells.” These cells capture photons, which are the main energetic components of visible light. Specifically, these cells provide photons with opportunities to separate electrons from atoms, which results in electricity.
Photovoltaic cells are composed of two thin layers of silicon. Other materials may also be used, but silicon, which is also present in all modern electronic devices, is considered to be the most efficient material for capturing photons. Each of these silicon layers is exposed to different substances to make them have opposite electrical charges.
The top layer of silicon is exposed to phosphorous, and the bottom layer is exposed to boron, which creates a dynamically opposing electrical environment that’s similar to the effect that occurs when you hold opposite poles of magnets together. When a photon removes an electron from an atom within the PV cell, the electrical field will push the separated electron away.
Next, conductive metal plates surrounding the solar cell capture these liberated electrons and transfer them to electrical wires. From this point onward, these electrons act the same as any other form of electricity, and they can be transferred down the line to batteries. Alternatively, solar cells can be used to directly power devices, though these devices will lose power if the PV panel’s access to sunlight is interrupted.
How Do PV Arrays Produce Usable Power?
A photovoltaic panel may be used on its own, or it might be part of a group of panels called a “PV string.” These strings of PV panels can either be arranged in parallel or in series; in a parallel arrangement, the wattage of the electricity generated by the panels increases per panel and not the voltage, and in a series arrangement, the voltage increases but not the wattage.
PV arrays can be directly connected to batteries as long as the voltage produced exactly matches the battery voltage. Since this is rarely the case, however, it’s usually necessary to route solar power through devices called battery controllers. These devices meter and control the energy coming from solar panels to make sure that it matches the voltage the battery can accept.
To produce usable 110V or 220V AC power, a further device, called an inverter, must be used. Inverters transform the DC power produced by the batteries or the controller into the AC power used by most appliances. The majority of inverters have normal electrical plugs built into them, and it’s also possible to wire power inverters directly into your home’s electrical grid.
Any excess power beyond that which you use may be fed back into the electrical grid, or it may be stored in batteries. Solar batteries of varying capacities exist on the market, and while a solar battery loses a portion of its capacity with each successive depletion and recharging, it can easily last between five and 10 years as long as it is paired with a high-quality solar controller.
While PV panels can only operate during the day, batteries can consistently feed power to your home’s electrical grid whether the sun is out or not. Therefore, with enough PV panels and solar batteries, it’s possible to power your home 24 hours per day.
Monocrystalline vs. Polycrystalline
Monocrystalline PV panels consist of solar cells with one type of silicon crystal, but polycrystalline panels contain more than one crystal type. If you’re looking for maximum efficiency, monocrystalline panels are the way to go.
These panels take up less space than their polycrystalline counterparts, but they produce more energy per square foot. While the process used to create monocrystalline panels is more wasteful, these panels last much longer than polycrystalline PV arrays, and they perform better in low-light conditions.
Installing PV Panels
In most cases, PV panels perform the best on the roof, but you should put your panels wherever they will get the most light. In traditional homes, PV panels are usually installed in rows along the sunniest side of the roof, but in RVs or other types of mobile homes, solar enthusiasts may choose to arrange their panels more eclectically to avoid vents, air conditioners, and other obstructions.
Differences in Solar Cell Quality
In general, cheaper PV panels don’t work as well as expensive panels. This trend is the result of the materials that are used to make high-end panels; while cheap panels might seem less costly in the long run, deviations between cells and micro-cracks in silicon wafers will make these panels fail much sooner than high-end options.
In addition, flexible PV panels are still plagued with problems. While the novelty of these panels makes them attractive, a flexible panel is much more likely to fail before the natural conclusion of its lifetime than a rigid glass panel. While flexible panels may be the way of the future, if your goal is to set yourself up with panels that provide the best performance, it’s best to wait until all the kinks are worked out of this relatively new technology.
The Future of Solar Energy
By 2040, the International Energy Agency (IEA) expects that PV panels will have completely replaced all other forms of energy generation. Whether or not this prediction will end up coming true, it’s undeniable that PV panels are taking on ever-greater prominence in the global energy industry.
Already, researchers are developing ultra-thin PV arrays that may eventually vie for supremacy with neutrino energy as the top technologies for mobile device power generation. Technologies for the efficient utilization of PV energy are also improving year by year, and the day is fast approaching in which every home will have the capability of sustaining its energy needs fully off the grid.