Net Metering Interconnection Agreement
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How Off-Grid Solar Electric Systems Work
In an off-grid solar electric system batteries are required. They store energy and allow the system to provide power during cloudy weather and at night. Many aspects of an off-grid system are similar to on-grid. The notable exceptions being the methodology used for sizing the system (an off-grid system typically supplies all the power requirements of the home, sometimes supplemented by a gasoline or propane generator), the inclusion batteries (for energy storage), and the addition of charge control equipment necessary for managing the charge and discharge cycles of the batteries. The inverters are also different in that they usually incorporate battery charging capabilities.
Off-Grid Solar-Electric Systems
How Grid-Tied Solar Electric Systems Work
Solar PV modules collect the sun's energy and convert it into direct current (DC) electricity. The amount of electricity produced is proportional to the amount and intensity of sunlight.
The number of panels is determined by the home or business's power needs. Typically 2,000 to 4,000 watts (2-4 kilowatts, kW). A DC to AC grid-tied inverter converts the electricity from DC to alternating current (AC) for use in a home or business. A rule of thumb is 100 square feet of PV module area per kilowatt (kW) of electricity produced by the PVs. A typical solar electric system for a home will require approximately 200-400 square feet.
A bi-directional (spins both ways) electric meter records and displays "net" power usage. Net power is the difference between what the solar electric system generates and what the electric utility provides to meet a home or business's total energy requirements. When more electricity is generated than is used, the meter spins backward, lowering the electric bill. When less electricity is generated, the meter spins forward, although at a slower rate than it would without the PV system. The overall result tracks the net difference as electricity is generated and sent off to the grid and as electricity is consumed. This, then, becomes the basis for payments (credits) to your electric bill. This all happens seamlessly and automatically. No user intervention is required.
Energy storage (batteries) in a grid-tied system is rarely needed or justified. The electric grid acts as "storage," accepting excess power that is produced and allowing it to be used by others. When the PV system does not produce power (nighttime) or produces less power (cloudy weather), the electric grid becomes the source, seamlessly switching over. While there are energy storage solutions, the cost--combined with a short lifespan and maintenance requirements--makes them less of a solution. Unless you're off the grid, storage rarely makes sense. Finally, not having batteries in a system reduces the overall cost and virtually eliminates maintenance of any kind.
Grid-Intertied Solar-Electric Systems with Battery Backup
Net Metering: Fortis's Net Metering program is designed for residential and commercial customers who wish to generate their own electricity using a "BC Clean" energy source such as solar, wind or micro hydro, and connect to the Fortis distribution system. When customers with their own generation capabilities produce more than they consume, they will receive a credit from Fortis that goes to their account and can be applied against future consumption charges or be paid out annually.
