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Parallel Inverters Battery Racks Configuration

WattAboutThat

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Dec 15, 2021
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I am very new and request guidance from more experienced solar system builders:

If you design a system with multiple paralleled inverters (half of them out of phase), should the battery systems (racked or otherwise) be on a common buss and then connected to all inverters from the single bussed battery as their dc power source? Or would it be better to divide the batteries such that each inverter has it’s own independent battery supply?

Same for pv panels - should they be separate suppliers to each inverter - or should they be bussed together and supply all inverters from the buss?

What are the pros and cons of each method?

Thank you
 
Bus the batteries all together. This keeps the load on them all the same. It also allows you to take one or more of the inverters off-line and still have the full battery capacity available. It also allows you to take a battery offline and not shut down the system.

I am not aware of an advantage to separating them.
 
Another question: Should all of the solar sources also be bussed together, then each inverter connected to the buss, in the same wayvas tge batteries, so all solar panels are feeding in parallel all of the inverters which then charge all of the batteries in parallel?

When all of the inverters are sending out a charge to charge the batteries, or when all solar panels are sending a charge, what prevents too much charge from one inverter from backfeeding the other inverters and blowing circuits?

thx
 
Another question: Should all of the solar sources also be bussed together, then each inverter connected to the buss, in the same wayvas tge batteries, so all solar panels are feeding in parallel all of the inverters which then charge all of the batteries in parallel?

When all of the inverters are sending out a charge to charge the batteries, or when all solar panels are sending a charge, what prevents too much charge from one inverter from backfeeding the other inverters and blowing circuits?

thx
If you have separate MPPT controllers, the panels are split among them, and they connect directly to the DC bus (which would be common to all inverters and all batteries). If youre using all in one inverters (that have built-in MPPTs) then obviously you'll be splitting the PV strings across those various units.

Edit:

My response lost sight of the question. In agreement with filterguy, you do not combine all of the PV on the same bus with multiple MPPT sourcing from it. You do combine multiple MPPT on the same bus as your batteries/inverters for feeding it. Each MPPT (AIO or not) should have its own string of PV to draw from.
 
Last edited:
Another question: Should all of the solar sources also be bussed together, then each inverter connected to the buss, in the same wayvas tge batteries, so all solar panels are feeding in parallel all of the inverters which then charge all of the batteries in parallel?

When all of the inverters are sending out a charge to charge the batteries, or when all solar panels are sending a charge, what prevents too much charge from one inverter from backfeeding the other inverters and blowing circuits?

thx
The short answer is no... you should not bus them all together.... but it is a bit more complicated than that.

As a general rule of thumb, the more MPPT charge controllers, the better....with the ultimate being one controller per panel. One per panel would mean that every panel is constantly optimized to get the max out of it and any shading or other issues on all the other panels does not impact it.
Generally speaking, MPPT controllers are expensive enough that this is not often done. (The exception being when micro-inverters are used, but that is not the situation you are in)

However, how you arrange the panels on each of the charge controllers will depend on several things...
- possible Shading or different angling of the panels
- Specifications of the solar panels
- max input voltage of the charge controller.
- Lowest temperature your area will get.
 
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