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Off-Grid and Grid-Tied Systems

data:2009-06-12

Difference between Off-Grid and Grid-Tied Systems

 

The basic difference is where the energy generation goes.

 

Off-grid system, often also called standalone system, consists of following:

Power Generation Source: Wind Turbine, Solar Panels, or together called Wind-Solar Hybrid

Controller: controls functioning of wind turbine or/and solar panels, rectifies the wild current from wind turbine and charges to the batteries.

Batteries: Stores electricity produced by Wind turbine or Solar panel. Also functions as a buffer to stabilize voltage and current

Off-grid Inverter: Inverts the DC current from batteries into stable AC for electric appliances like lighting, TV , Microwave Oven etc.

 

Grid-tied system, or by the name of on-grid system, consist of following:

Power Generation Source: Wind Turbine, Solar Panels, or together called Wind-Solar Hybrid

Controller: controls functioning of wind turbine or/and solar panels, rectifies the wild current from wind turbine and provides DC to grid-tied Inverter. (Controller is not necessary for solar grid-tied system due to the stable character of solar generation.)

Grid-tied Inverter: Inverts the DC current from controller or solar panels into stable AC and transmits directly to the home appliances, excess electricity to the State Grid.

 

By comparison, we can find their difference is batteries and power destination. Off-grid system must have a battery to store energy for inverting. On the contrary, grid-tie system does not need batteries. It transmits the power directly to the home appliances and state grid.

 

In many countries, grid-tied system is very popular. It does not require expensive and heavy batteries, meaning lower total cost. User is able to make money by trading excessive electricity with utility companies, getting faster payback of the system. However, user must get local authority permission for grid connection before installation.