How Grid-Tied PV Works

Grid-tied systems use PV modules to integrate solar electric power with existing electric utility power. As a grid-tie system generates electricity, it sends energy back to the utility power grid.

Grid-tie systems participate in net and production metering programs. The utility company will pay you to produce energy for them, and the energy you produce counts against the energy used by your home or business.

Batteryless grid-tie systems are the most popular type of PV grid-tie system; they are simple and efficient, providing power to residential and commercial spaces.

1.  In a batteryless PV grid-tie system, DC electricity is generated by PV modules.
   
2. Next, the DC electricity is converted into usable AC power by an utility-interactive inverter.
   

• If a string inverter is used, many PV modules will be connected to one central inverter. String inverters, such as the Sunny Boy, may be wired to a single series string of 12-24 PV modules.
• If micro-inverters are used, then each PV module will interface with its own individual inverter device.

   3. When the output of the PV modules exceeds the demand of the loads requiring electricity, excess power is diverted to the utility grid.
Grid-tie systems are eligible to participate in net and production metering programs, allowing you to sell-back excess production of electricity to the local utility.

Battery-based grid tied systems employs batteries as a part of grid-tie system architecture to provide backup power in the event of an outage (UPS). Adding battery capacity will reduce overall system efficiency by 10%. They require periodic maintenance, which may be performed by an informed system user.

1.  In a battery-based PV grid-tie system, DC electricity is generated by PV modules.
   
2. A charge controller regulates the amount of charge going from the PV modules to the batteries. This is to protect batteries from being over- or under-charged.
   
3. Next, the DC electricity is diverted into batteries for storage. A battery bank (set of batteries connected together) serves as a backup power source (UPS) in the event of a grid outage.
   
4.  The energy collected in the battery bank is converted by an inverter for use as AC power.
   
5.  When the output of the PV modules exceeds the demand of the loads requiring electricity, excess power is diverted to the utility grid. Grid-tie systems are eligible to participate in net and production metering, allowing you to sell-back excess production of electricity to the local utility.