Solar Basics: Role of a Panel


Solar Panels

One of the most important and easily recognizable components in a solar system consists of the solar panel itself. A solar panel is made up of special photovoltaic cells specially designed to absorb light and convert it into electricity. This process happens thanks to the photovoltaic effect.As the sun shines, photons of light strike the cells and knock electrons loose from the cells' atoms. The flow of these electrons through the panel generates an electrical current — specifically a direct current. As this current moves through the interconnected panels in a one-way direction, it eventually reaches a second component known as the inverter.The inverter changes the direct current (DC) into alternative current (AC) electricity, which is then capable of powering everything from lightbulbs to complex industrial machinery. Some solar systems also utilize batteries which can store the energy generated by the solar panels for future use.

Components of a Solar Panel

While it is easiest to think of a solar panel as a single, unified object, there are actually many discrete components that make up a solar panel, including all of the following:

  • Solar (photovoltaic) cells
  • tempered glass
  • aluminum frame
  • encapsulant layer
  • backsheet
  • junction box

The most important of these components are the photovoltaic cells discussed above. Also known as solar cells, these cells are grouped together in modules. A single solar panel, in turn, consists of numerous solar cell modules. Most commercial solar panels contain either 60 or 72 cells in total.The solar cells inside of a panel also receive protection from the component known as the encapsulant layer. This thin film keeps out moisture while still allowing electrical and optical transmissivity. A variety of different encapsulant materials exist, including ethylene vinyl acetate, ionomers and polyolefins.These solar cells are additionally protected from the elements by a sheet of tempered glass. Tempered glass differs from standard plate glass in that it has been toughened through either chemical or thermal means, giving it a strength many times greater than that of normal glass. Furthermore, most tempered glass receives an anti-glare coating to reduce its reflectivity so that the maximum amount of light can reach the productive cells.The tempered glass is secured in place by the solar panel's aluminum frame. The panel's frame also plays a number of other key roles, making the panel easier to handle, store and affix in place. The frame also increases the panel's resistance to physical loads placed on it by wind and snow.The backsheet provides protection against the DC voltage generated by the action of the solar cells. This layer of laminate consists of polymer materials that act as an electrical insulator, while also protecting against UV radiation, extreme temperature swings, and humidity and vapor incursion.Finally, the junction box acts as an enclosure for all of the otherwise vulnerable electric components that make a solar panel work. The bypass diodes inside of the junction box also ensure that power only flows in one direction through the system, thus preventing electrical energy from feeding back into the panels.

Solar Cell Types

Around 90 percent of the photovoltaic cells in solar panels today are made from silicon, which has a long history as a material used to create electrical components. Silicon naturally has incredible semiconductor properties. By adding in minute quantities of other elements, the conductivity of silicon can be greatly enhanced.That said, a surprising amount of diversity exists within the world of silicon solar cells. Today there are three main types of silicon cells on the market: monocrystalline, polycrystalline and thin film. Monocrystalline solar panels are generally considered the highest quality solar cells. For one thing, they boast efficiency ratings as high as 20%.Monocrystalline silicon derives its efficiency from its physical structure. Each cell in a monocrystalline panel consists of a single crystal of silicon. Manufacturers create these cells by forming the silicon into bars and then cutting them down into wafers. Polycrystalline panels, by contrast, are made by melting multiple silicon fragments together into a wafer.As its name implies, each cell of polycrystalline contains multiple crystals of silicon. This decreases efficiency by making it more difficult for the electrons to move through the panel. As a result, polycrystalline solar panels see their efficiencies capped at around 16% — lower than the efficiency of monocrystalline panels.Finally, there are thin-film solar cells, which hold appeal for certain applications thanks to its flexibility. While thin-film solar cells can reach maximum efficiency of 17% percent, they are generally not employed for most residential and commercial purposes.Solar technology has been proven to deliver efficient and economical results as a power source and has come a long way over the past several decades. PowerFlex has been a leading solar provider to the commercial market for over a decade, and we have built strong relationships with the most reliable and efficient panel providers. We work closely with each client to provide a customized solar solution and stay up-to-date with the latest technological developments in the industry. To learn more about what type of solar equipment can best meet your needs, please don't hesitate to contact us.