Inverter uses battery power and excess goes to grid, at night inverter uses battery power and if batteries get low then switches to grid power and also charges batteries.

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Hello,  If I am understanding the question correctly, you are wondering how to set the inverter so that it will charge the battery bank at night when the batteries are discharged below the system's depth of discharge setpoint?  

If so, this is a setting that is native to many battery based grid-tied inverters that is acheived by using the inverters programmable interface. This means that when the system's battery bank becomes overly discharge the grid can take over the critical loads again whilist charging the batteries. This would be superceeded once the sun comes up and there is ample solar resource available to charge the batteries with the PV.  

A follow up question; what grid-tied battery backup inverter is being used?  With that I may be able to point you in the right direction if I have interpreted the question correctly.

You have most of it correct. I need to know what equipment or inverters are needed to run the system from the batteries or PV panels if there is enough 24V power to charge the batteries and if there is anything left over feeds the grid.

I think I have enough battery power to power everything all night but if there is not enough sun for a day or two it may revert to grid power.

I heard something about needing two different types of inverters.

I only need 3000 watts for this first set up.

 

Hi David,

So you may or may not actually need to have a separate inverter to accomplish this feat.  My guess is that you won't because many battery inverter have both off-grid and grid-tied functionality.  The best starting place for me to help determine this is to find out what your current inverter make and model # are.  

As an example an Outback's GTFX and GVFX inverters are grid-interactive battery inverters. If the utility power goes down, these inverters can isolate themselves from the grid and use your battery bank and/or your PV to power your critical loads. The inverter can be set up so that either utility power or your PV can be used after an outage to recharge the battery bank. 

Your getting close......I don't want to use the Grid power unless the batteries get low....I want to be using the batteries and charging from the PV panels and if there is any excess then it would be fed back into the grid....I am just starting to build the system and don't have the inverter as yet and my sales man told me to check out being able to do what I want to do first.
Submitted
10 years ago
Asked by
David Passwaiter