About Solar Panels
Solar Panels / Solar Modules are one of the important element for producing solar energy. Luckily, renewable resources like solar energy are steadily becoming a larger part of our country's energy profile, and since solar energy comes from the sun, it represents a limitless source of power. In just one hour, the amount of solar power delivered by the sun is more than the entire world uses in a year. But current electricity demand in the US is mostly met by consuming fossil fuels like oil and gas, and we are nearing the brink of exhausting these nonrenewable resources as our planet’s population continues to rise.
To harness the sunlight and generate power for your home or business, a solar photo-voltaic (PV) system is required. These are also known as solar panel systems, solar energy systems, and solar power systems, and all of them start with the most recognizable part of the PV system: solar modules (known more commonly as solar panels).
More About Solar Panels / Modules
Solar Panels / Modules are made up of an assembly of connected solar cells, and these are the blue or black “squares” seen on modules/panels. Solar cells are typically made of silicon, an element with conductive properties that generates an electrical current when exposed to sunlight, also known as the photo-voltaic effect. An array is created when solar modules/panels are grouped together in a series or in parallel on a roof or ground mount.
Number Of Cells
Most solar modules/panels in the residential and commercial markets are made up of 60 or 72 solar (photo-voltaic) cells, although there are certainly other grid sizes available. Choosing the right type and number of solar panels depends mainly on the energy requirement (how much power is needed), available space for the solar module/panel array, and budget constraints.
Types of Solar Cells
The most common types of solar modules/panels are mono-crystalline, poly-crystalline and thin-film, and their differences start during the creation process.
Mono-crystalline silicon is created by slowly extracting a mono-crystalline silicon ingot out of melted mono-crystalline silicon. This cylinder of high-purity silicone is then sliced into thin wafers for use as solar cells.
Poly-crystalline silicon is created through a simpler process. Instead of using the slow and more expensive process of creating a single ingot, molten silicon is poured into a square mold and cooled before being sliced into thin wafers that are perfect squares.
Thin-film panels are made by depositing one or more thin layers of photo-voltaic material on a substrate, and these materials are usually silicone, cadmium telluride (CdTe), copper indium gallium selenide (CIGS), or organic photo-voltaic cells (OPC).
Hetero-junction is a new cell technology that design in such a way that it's combine the advantages of crystalline silicon solar cells and thin-film solar cell which make them more efficient and required low cost of production. Hetero-junction cells show a considerably lower temperature coefficient and have efficiency rates of more than 24%.
Here is a quick comparison of the three based on the following criteria:
Mono-crystalline cells have a dark uniform color that typically show up as black, but poly-crystalline cells have visible differences in color shades due to the varied crystal structure, and they typically show up as blue. Mono-crystalline and poly-crystalline cells are rigid and as a result, the panels do not bend.
Thin-film cells are diffused onto a substrate with very thin layers, and the panels will look almost solid in color with very narrow lines. These lines are formed by the chemical etching process that produce each cell, and the completed panel is fairly flexible.
Mono-crystalline solar cells cost more than poly-crystalline solar cells of the same size. Thin-film solar cells are cheaper than both mono-crystalline or poly-crystalline.
Due to being made from one large crystal as opposed to many small ones, mono-crystalline cells have a higher efficiency (typically 15% to 20%) than poly-crystalline cells (typically 13% to 16%). In addition to better overall efficiency, mono-crystalline panels tend to perform better than poly-crystalline panels in high ambient temperatures. Thin-film cells are the least efficient (typically 7% to 9%) in terms of power production.
Since mono-crystalline cells are more efficient than poly-crystalline cells, the size of a mono-crystalline solar module/panel is less than a poly-crystalline module/panel of the same wattage. In other words,if you are limited on space and want to generate the most power possible, mono-crystalline modules/panels are the way to go. Thin-film modules/panels require the most space to produce the same results as either a mono-crystalline or poly-crystalline module/panel.
Mono-crystalline and poly-crystalline panels have the potential to last up to 50 years, however most power warranties are only for 25 years. Thin-film panels are still rather new and their life expectancy is unproven, but the design expectation is 20 years.