Why Solar: Basics of Solar
- PV is an acronym that stands for photovoltaic. The term photovoltaic represents the union of two words: photo meaning light and voltaic meaning electricity. Photovoltaic systems convert light energy, photons, into elecricity through the photoelectric effect.
- A complete solar electric system is made up of several building blocks. At the smallest level there are solar cells. Cells are manufactured from semiconductor materials, such as crystalline silicon, sometimes "doped" with boron and phosphorous. Cells are electrically connected and packaged to form a solar module.
- Solar modules are wired together in series and parallel to create the PV array, producing direct current (DC) electricity when exposed to sunlight. Because almost all commercial buildings utilize alternating current (AC) electricity, the PV generation must travel through an inverter, which changes the DC electricity from the array into AC electricity for the building's consumption.
- PV systems are either roof mounted or ground mounted. The mounting systems and securing methods are determined by type of roof, available space, structural requirements, etc.
- The balance of system (BOS) components include racking, clips, switchgear, junction boxes, conduit, grounding equipment, meters, and the Data Acquisition System (DAS).
- The DAS is typically viewable online as it monitors, records and displays the PV system's performance. Web-based monitoring is a critical component of proper operations and maintenance (O&M) procedures.
- O&M is performed by qualified solar technicians and can include visual inspections, monitoring output, cleaning, electrical testing, troubleshooting and warranty support.
Step 1: Sunlight strikes the modules.
• When photons from the sun reach the solar module, a certain portion are absorbed by the cell's semiconducting silicon, knocking its electrons loose and channeling them into a flow of DC (direct current) electricity.
Step 2: The direct current is carried to an inverter.
• An inverter changes DC (direct current) into AC (alternating current)—the type of electricity we use almost exclusively to power our homes and businesses.
Step 3: The alternating current is integrated into your available power supply.
• AC electricity flows from the inverter into the building's electrical service gear, where it is drawn as needed into electrical loads throughout the facility.
Step 4: Excess generation flows back to the electrical grid for others to use.
• Any excess power produced by the PV system flows back into the grid through a bidirectional "net meter" (causing the meter to spin backward). The utility will credit a customer's account with the excess electricity produced and delivered back to the utility grid. This credit is at the retail rate rather than wholesale, thus maximizing the economics for the system owner.
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