Is it possible to have a solar pv system with batteries power my home with the GRID as backup power?

Posted on August 28 2010 by Helen Woods

I’ve bought books and read many instructionals/articles etc etc online, but all of them give three options…Off-Grid, Grid-tied or part Off-Grid and part on the Grid.

I’d like the option to power my home from a battery bank (windmill and solar panel charged) and have to grid as backup. Either the grid takes over when the battery charge is low or the grid charges the batteries when the charge gets too low. I know that there’s an issue with the types of electricity, but don’t they make Inverters or other devices that can make this possible?

Where I live there’s enough sun and wind to go off-grid, but I’d like the grid to be there as a backup just incase.

If you can advise me or point me to a book or website that explains how to do this…that’ll be great.

Thanks in advance for your help.

Curtis

Answer

The grid is really your battery. The reason why you don’t find the solar power configuration you are describing in books or articles is that in practical use it does not make sense.

I understand why you might want to go this route, as it makes you feel somewhat independent but have the safety of the grid when you need it — but please, it does not make sense and is not green either.

  • A grid-tied system basically uses the grid as a giant battery, by giving it power when you have too much and taking back when you need it.
  • In comparison to a battery, the losses are small.  Batteries give you back significantly less kWh than you put into them, unlike the grid.
  • The grid-tie means you don’t have to buy batteries which are made of toxic chemicals.  (Without going into much detail I think you believe me that “lead-acid batteries” are not the greenest building material around.)

Embrace the grid as the best battery ever invented, and charge it with energy from your renewable systems.

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