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diy solar

Phase Synchronizing???

CMA

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Dec 7, 2020
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I have (3) Delta H6 Hybrid inverters. They sync just fine to the grid - but I've been told - when operating them off-grid - they will not sync with each other. Does anyone know if it is possible to sync them in a grid-down - no battery scenario?

I have an 18.6kw solar array - but grid-down - I can only use one of the inverters without major re-wiring (which I obviously want to avoid.)

I don't want to add batteries. The grid is very stable here. If the grid does happen to go down for more than 24 hours - I want to use the panels in the daytime, then a generator at nighttime. Does anyone know how I could make this work?
 
Your inverters need somewhere to put the excess energy your panels produce above what your home will consume ast any given moment. That's why you'd need a battery. Inverters typically can't throttle an array down to match instantaneous power demands.
 
I understand what you are saying, but these inverters are designed to provide power in a grid-down situation. There are others that are capable of doing the same, such as some SMA inverters. How are they doing this?

Also, in a total off-grid situation, where there is battery backup - once the batteries are full - oftentimes there is still a vast amount of energy being produced (but not used) by the array. Where is that energy going?
 
...such as some SMA inverters. How are they doing this?...

Don't know about your brand of inverter, but some (e.g., Magnum) have a special cable that runs between them to synchronize the phases. Your inverter documentation or manufacturer should be able to tell you what's needed and how to do this. Hope that's of some help!
 
They are Delta H6 Hybrid inverters. There is no documentation that I can find that says they can be synced together off-grid. The rep from the company I buy them from, is the one who told me they could not be synced off-grid. They aren't very expensive, but I didn't want to try it to see what would happen.
 
Sounds like it won't work then as-is. Ask your rep if they have integrated with any other vendors to provide a solution for this.
 
I have (3) Delta H6 Hybrid inverters. They sync just fine to the grid - but I've been told - when operating them off-grid - they will not sync with each other. Does anyone know if it is possible to sync them in a grid-down - no battery scenario?

If these inverters can operate without a grid one at a time, then they each have a way to switch to a mode whereby they generate a 60 Hz sine wave output. That is what you have done to use just one of them off-grid. It thus seems that you should be able to set one up as "the grid" generating a stable 60 Hz wave, then turn the second one on in grid-tie mode so that it will sync to the first units 60 Hz wave. I.e., one in non-grid-tie mode and the other in grid-tie-mode with the non-grid-tie one operating before the grid-tie one is connected to it.

Alternatively, you might use a smaller conventional non-grid-tie inverter as the "grid" and have the two Delta H6 inverters sync to it.
 
These are old Solar City inverters that were never sold after Tesla bought Solar City. I doubt that they are built to UL1741SA so they are limited in how effectively they can AC couple to each other. Adding batteries may be the only workaround to get more than one to produce when the grid is down. These were designed to run the original phase one Powerwalls which ran at 380 volts.
 
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