SPG Solar, Inc. (SPG) designs performance-based solar systems to collect the most sunlight possible and thereby produce the most electric power. Each system is monitored in real time using SPG’s proprietary SunSpot™ software to verify the solar system’s performance.
When a solar system is designed to maximize electricity generation, fewer PV panels and less space to mount them are required to hit energy production targets. This eliminates the cost of installing extra panels that would otherwise be needed to meet the annual electricity production goal.
For optimum performance, the following factors are critical:
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For North America, the standard for optimal collection of sunlight is to orient PV panels to true south and tilt the panels so they face the sun throughout the year at an average 90-degree angle. At the general latitude of Northern California, this angle is 22 degrees from horizontal. SPG designers use a special compass-like instrument called a “Solar Pathfinder” which indicates specific areas of the installation site that will maximize a solar system’s electric generation capability.
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Solar modules should be mounted at a tilted position to allow cooling air flow across their front and back surfaces. Like computer chips, PV modules are primarily made of silicon. They use air flow to keep cool and lower electrical resistance, which helps maximize electricity production.
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Dust in the air gathers on PV modules just like it does on a car. The fine coating of dust that dulls a car’s finish also reflects sunlight off the surface of a PV module—preventing light from penetrating the glass cover to generate electricity. Tilted modules are more productive because they stay cleaner by shedding dust when it rains and by keeping falling leaves and other debris from accumulating on the surface of the panels.
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Designers must also take into account shading that will degrade the amount of power produced. A shadow on one corner of a solar array will lower the production of an entire circuit of panels. Any panels that the system designer knows will be shaded should be connected together on an isolated circuit. By doing so the panels that receive full sun are able to produce electricity to their fullest potential, and electric production of the entire solar system array is maximized.
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Experienced electricians look for ways to minimize line loss in solar systems. Solar panels selected for a system should be matched on each circuit for electric output. Solar panels wired together in such a circuit are able to produce only the energy that the lowest-performing panel is able to produce. The low-performers should be circuited together, and the panels that perform at or near the highest potential should be on their own separate circuits.
To ensure the maximum return on investment generated by each solar system, businesses, government agencies, non-profits and homeowners that are considering solar should look carefully at the factors that go into a proposed solar system, and then verify the record of the designer/installer. Installation techniques also count, and the best electricians in the solar field generally get consistent results from their solar installations.
