Below, you will find information on four types of photovoltaic solar power systems.  There are more than 4 photovoltaic solar power installation configurations, this is an overview some of the most common set-ups.

Stand Alone System – A stand alone photovoltaic solar power system provides electricity generated from the array to the point of consumption and is independent of the utility grid.  Stand alone systems generally use a battery storage system to provide electricity to the load when the solar array is autonomous and unable to generate power.  A more sophisticated stand alone system adds an inverter and ties into the building service panel.

Grid Tie System – A grid-tie system is also called a utility interactive system.  This type of solar power system operates in tandem with the local utility supplier.  It uses an inverter to convert DC power to AC power, ties into the service panel supplying electricity at the point of consumption from the solar array. 

It also ties into the utility grid and sends electricity back to the utility when the energy produced by the array is not consumed at the point of consumption.  The term net-metering is used to describe the offset of electricity used from the grid and the electricity sent back into the grid.

Grid Tie with Battery Backup – Also known as a bimodal system, a grid tie system with battery backup is also a tandem system that can operate as a grid-tied utility interactive PV system as well as a stand alone system which can draw power exclusively from the batteries in the case of a blackout, even at night when no electricity can be drawn from the solar array.

In the utility interactive mode, the system can be set up as net-metered using a bidirectional utility meter or dual metered, using two utility meters.  One for importing power from the grid and one for exporting electricity generated from the solar array back to the utility company.

This is a sophisticated system that accounts for autonomy in electricity production, but comes with a higher price tag than stand alone or simple grid tie systems.

Hybrid Systems – a basic hybrid system is configured as a stand alone system that uses electricity generated from two different sources.  A solar array combined with a wind turbine would be an example of dual energy sources in a hybrid system.  Hybrid systems are sophisticated and complex.  A standard hybrid system converts power from the energy source from DC to AC using and inverter and ties into the AC electrical panel where the electricity is used at the point of consumption.

By: Rick Contrata

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