SOLAR PV SYSTEM
ON-GRID TIED SOLAR SYSTEMS
Also Known As: On-Grid, Utility-Interactive, Grid-Intertied, or Grid-Direct
Grid-tied systems are the most common type of solar PV system. Grid-tied systems are connected to the electrical grid, and allow residents of a building to use solar energy as well as electricity from the grid. Grid-tied systems do not need to produce 100% of the electricity demand for a home or business. When there is no demand for energy, the solar panels send excess electricity back out into the grid for use elsewhere. When a home or business is using energy, but the solar panels aren't producing enough energy (at night, or on a stormy day), electricity from the grid supplements or replaces electricity from the panels.
Owners of a grid-tied system complete a net metering agreement with their utility. This agreement allows utility customers to receive credit for the excess energy they generate, typically credited as a kilowatt-hour credit on the next month's bill. Net metering policies and agreements are different for each utility. Living with a grid-tied solar PV system is no different than living with utility electricity, except that some or all of the electricity you use comes from the sun.
Grid-tied systems do not provide protection from power outages. When the electrical grid fails, grid-tied systems will not continue to operate. This allows utility employees to fix the power lines safely without wasting time identifying solar energy systems that are still feeding electricity into the power lines.
System components:
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PV panels (multiple panels make up an array)
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inverter(s)
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required electrical safety gear (i.e. fuses, breakers, disconnects)
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monitoring system to monitor energy production (optional)
OFF-GRID SOLAR SYSTEM
Also Known As: Battery Backup Systems/Stand Alone
It is possible to install a solar system that is independent of the electrical grid.
This is called an off-grid system, and it requires that the solar panels are able to produce enough electricity to cover 100% of the energy needs of the building. Most homes have higher electricity demand in the evening or at night, so off-grid systems usually incorporate either a battery (to store energy produced during the day), a backup source of energy (like a generator), or both. Off-grid systems are more complex and less flexible than grid-tied systems.
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Off-grid systems are most common in remote locations without utility service.
Off-grid solar-electric systems operate independently from the local utility grid to provide electricity to a home, building, boat, or RV (or remote agricultural pumps, gates, traffic signs, etc.). These systems typically require either a battery bank (to store solar electricity for use during nighttime or cloudy weather) a backup source of energy (like a generator), or both.
An off-grid solar system must be large enough to produce enough electricity to cover 100% of the energy needs of the building. In all off-grid scenarios, electrical usage must be monitored and kept below the maximum output of the panels and batteries as there is no grid-source to supply excess power.
System components:
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PV panels
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battery bank
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inverter
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required electrical safety gear (i.e. fuses, breakers, disconnects)
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monitoring system to balance energy consumption with production
ON/OFF HYBRID SYSTEM
A Combination of On-Grid and Off-Grid System.
A hybrid system is one in which your solar panels are still connected to the grid's power wires while also having a backup battery system to store surplus electricity or excess power.
The advantage of a hybrid solar system is that you will always have power in any situation. The extra energy generated by your solar panels (but not used by your home) is saved in a backup battery. When the sun is not shining, this battery will supply electricity during the night, system outages, or severe weather.
A hybrid solar system works by directing solar energy to your inverter, which then distributes electricity to your home. Excess energy that is not needed to power your house is stored in your home battery. When your solar panels are not producing electricity, this battery can offer power to your home. If there is any energy left over after all of these stages, it is transmitted to the grid.
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A hybrid system is an excellent way to gain control over your power supply. With solar panels and a backup battery, you may be your own energy source while also being linked to the power grid.