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Photovoltaic (PV)

Photovoltaics (PV) is a technology that converts light energy into electricity.  PV produces electricity from a clean, renewable source without noise or air pollution.  The basic unit of a PV system is the solar cell, a small, square-shaped semiconductor made from silicon or other conductive materials.  Approximately 40 solar cells make up a solar module (more commonly known as a “panel”).  Panels grouped together make up an array.  Finally, arrays grouped together form a solar system.  A typical PV system has a PV array(s) and a control center containing a DC to AC inverter.  Alternately, some systems have micro-inverters attached to each panel.  Some people add batteries to their system in order to store the unit’s output for use at night or as a backup in case of a power outage. 

Solar panels can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture more sunlight than fixed angle systems.  For utility or industrial-scale applications, hundreds of solar arrays are interconnected to form a large PV system, also known as a solar farm.

The basic PV or solar cell produces only a small amount of power. To produce more power, cells can be interconnected to form modules, which can in turn be connected into arrays to produce yet more power. Because of this modularity, PV systems can be designed to meet any electrical requirement, no matter how large or how small.

PV System Diagram

PV systems are generally classified according to their functional and operational requirements, their component configurations, and how the equipment is connected to other power sources and electrical loads.  The two principal classifications are grid-connected, also referred to as utility-interactive, and stand-alone systems.  Grid-connected systems operate in parallel with and are interconnected to the electric utility grid.  Therefore, when a grid-connected system generates more electricity than the home or business uses, that electricity flows back into the grid and the electric utility will buy that electricity from the customer.  (For safety reasons, grid-connected systems do not operate when there is a power outage) Stand-alone PV systems generate their own electricity and operate independent of the electrical grid.  They typically include battery storage so the users can access the electrical energy when there is no sunlight.  None of these systems use any water to generate electricity.

Diagram of Grid-Connected Photovoltaic System

Diagram of Stand-Alone PV System with Battery Storage Powering DC and AC Loads.

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Pima County Solar One Stop (520) 740-6463

The Solar One Stop is a multi-agency, collaborative effort led by Pima County and the City of Tucson, with funding provided by the U.S. Department of Energy's (DOE) Solar America Communities Initiative. The goal of the program is to spread the news about affordable, quality, and efficient solar technologies for homes and businesses.
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(520) 740-6463