The two major types of solar electric systems are

• Stand alone system, also known as a battery or off-the-grid.
• Utility-tied, better known as either grid-connected or grid-tied.

Assuming you have a sunny location with the proper orientation, there is a decision to be made: Tie into the grid or go with a stand alone system? The differences revolve around the storage systems, the accessibility of the grid, and the time and money involved.

For some this is an easy decision; for others, it is more difficult. And for those who live in rural areas, there is often no choice but the stand-alone system.

Consider these pros and cons of each system before making your decision.

An "off the grid" or "stand alone" system:

• Must supply 100% of your electricity needs--thus must be larger.
• Is more expensive to install and maintain than a grid-connected system.
• Requires management and maintenance of the battery bank.
• Uses batteries which have a limited life and must be replaced at intervals of time.
• Is still operational when a grid is experiencing an outage.
• May require a fossil-fuel generator if the system is down for any length of time.
• Is more practical when a home is more than several hundred yards from an existing power line.

An "on the grid" or "grid-connected" system:

• Can supply any percentage of your home's electricity needs.
• Is less expensive to install than a stand-alone system.
• Requires little-to-no maintenance or replacement of parts.
• Is only operational during sunlight hours even when the utility grid is experiencing an outage.
• May require a fossil-fuel generator or battery storage if the grid is down for any length of time.
• Is more practical when net metering is available.
• Is more practical when the home is close to utility lines.

Remember:

1. Any PV system can be installed as a single power unit, or as a hybrid system in conjunction with other sources of electricity such as wind or water power.

2. Either can also have backup power such as a fossil fuel generator.

3. A grid-tied system can be installed over a period of years as budgets allow. It may not as cost effective, or even possible to do that with a stand-alone system.

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