1) Introduction to Solar PV
Page 1, Image of single solar module

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What is a solar photovoltaic (PV) system?

Solar PV systems come in many different sizes and types. A system could be as simple as a single PV module connected to a water pump, designed to pump water when the sun is shining. The most common PV systems found are called grid connected systems and they usually contain many PV modules, racking, an inverter(s), and a bidirectional meter.

The smallest component of a solar PV system is called the solar cell. Many cells, usually 60 or more, are wired together to produce a single PV module or solar panel. The two terms, modules and panels, are often used to describe the same thing a single PV module; however, using the term module is more accurate and is less likely to cause confusion. Technically a number of modules wired together is called a panel. Finally, when several panels are wired together they form an array.

PV modules are sold in a range of sizes (e.g. 60 or 72 cell ) and power outputs (e.g. 270 watts). The materials, the processes, and the technology used affect the cost and efficiency of the modules. An interesting fact for those of us living in colder regions is that the voltage and the efficiency of a modules increases with colder temperatures.

Most modules produce DC electricity, a car battery also provides DC power. When connected to the electrical grid in the city this electricity is converted to alternating current (AC) electricity by the inverter so that it can be used in your home or business. AC electricity is the energy required by most electrical devices.

Batteries can be included in grid tied systems to provide backup power, but they are mostly used in off-grid systems. Batteries are nice to have, but they add cost to a system and they may require maintenance. In grid tied systems there are inverters available that have the ability to provide backup power, but they only provide power when the sun is shining.

Solar PV systems produce the most energy on sunny,  summer days where there is little cloud cover and the sun is high in the sky. The greatest production happens when the sun is perpendicular to the surface of the modules. This point in time will depend on the angle that the modules were installed at, often the angle of the roof, and the time of day and the time of year.


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