The solar cell is the basic building block of all solar electric systems. When sunlight strikes the solar cell, an electron is freed creating a small amount of direct current. This energy is produced silently, with no noise, no moving parts, and zero emissions. Solar cells can be made from any type of semiconductor, and they are most often made from silicon, which is one of the most abundant elements in the earth's crust.
Solar Module
Solar Modules
Solar modules, also referred to as solar panels, are comprised of numerous solar cells wired together in series and encapsulated behind a protective barrier, typically glass. The cells are wired in series to produce a usable voltage. Usually solar modules have an aluminum frame to provide mechanical strength and to allow for secure mounting of the module. When numerous solar modules are wired together in series, they comprise a solar array.
Solar modules are offered in a variety of physical dimensions and power output capacities, depending on the technology, efficiency and manufacturer. For grid connected installations, modules typically range anywhere from 10-25 square feet in area and the output can be anywhere from 100 watts to 300 watts. For residential applications most solar modules are less than 250 watts.
Inverter
Inverter
The inverter is the brains behind the PV system. It is the device that converts the DC electricity produced by the solar modules into AC electricity that is used by the appliances in your home or business. In grid-tie applications, the inverter also synchronizes the AC output with the utility power to ensure that the two work together to seamlessly provide electricity. In order to do this, the inverter constantly monitors the utility power to make sure it is within certain specifications, and as a safety measure, it will shut down if the utility power deviates from these parameters. (For more information about this, see the following section on PV System Types)
Inverters come in various physical and electrical sizes, and a Solar PV system may contain more than one inverter, depending on the size and configuration of the system. Depending on the installation the inverter may be connected to the grid at variuos voltages as well. Typical connection voltages are 240 volts for residential installations, and 208 volts, and 277 volts for commercial applications. For larger commercial PV systems the interconnection voltage may even be at 480 volts. Inverters for residential instalations typically come in power ranges from 3 KW to 10 KW. Inverters larger than this are typically used for commercial applications and are usually configured for three phase applications.
Racks & Mounting Systems
Whether on a roof, a pole, or the ground, solar modules must be securely mounted. The mounting system must be wind and weather resistant. Aluminum mounting systems are widely used in the industry because aluminum is strong, yet light weight, and corrosion resistant. Typically, the systems also utilize stainless steel hardware, making them more maintenance free.
Batteries store the electrical energy collected by the solar modules during the day. While the type and size of the batteries depends on your application and budget, they all perform the same function-- to store electrical energy for use when needed. Batteries for PV systems differ from typical car batteries in that they are deep cycle. Whereas car batteries are designed to supply large amounts of energy over a short period of time, deep cycle batteries are designed to be discharged over a long period of time, and can discharge up to 50% of their overall power without decreasing their capacity and longevity.
The charge controller controls how the batteries are charged, monitoring the state of charge to ensure that the batteries are not overcharged. This greatly enhances the capacity and lifespan of the batteries
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