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Hi,

I'm looking to setup a half on grid, half off grid parallel hybrid inverter to charge the batteries from a 3kw generator. I might also use some of the additional MPPT gained by the second inverter in the future, but only for battery top up.

Picture of planned setup....



Is this even possible? Would the canbus connections to the seperate on and off grid inverters confuse things? What about grounding on the non grid side.

Thanks

Interested in this thread, thought you had to parallel same size inverters though?

Yes should be possible. The thing to be carfull with re CAN is the max charge and discharge settings to the inverters. If the bms says 50A you don't want that 50A from both inverters as that would be 100A.
Ideally you want the max 50A but read the power coming from each inverter and subtract that from the setting to the other inverter.

All i can say is that the ECCO hybrids do allow a generator connection to them individually (or a wind turbine), and can be run in parallel. How they would work/be wired is well past my understanding/ability tho

Tinbum - that's a very valid point. Would the BMS not limit the charge though? I guess in the event of wanting to use the generator I could make sure the grid tied charge was turned off. It also begs the question if the grid tied inverter could still use the batteries whilst the off grid side charges?

resybaby - thanks. The only issue with the aux/load port is that it will be used for the microinverters. Plus the generator will not be synced with the hz on the grid side, hence the reason for an offgrid parallel setup.

AGT - good point, I wonder if it really matter if the inverters are matched?

Silverwings wrote: ↑Sat Sep 21, 2024 3:59 pm Tinbum - that's a very valid point. Would the BMS not limit the charge though? I guess in the event of wanting to use the generator I could make sure the grid tied charge was turned off. It also begs the question if the grid tied inverter could still use the batteries whilst the off grid side charges?

I guess it would depend on the BMS but I would plan for it not to. I think too many times people think the BMS does more than it does. I think of the bms being there to tell the inverter what to do and then if something goes wrong it will activate its internal safety features, which on many is disconnecting the battery..

Yes the grid tied would be able to use them as the other side charges. If the grid side is using less power than the off grid side is charging then the battery will charge. If not then its just like the generator power doing straight to the grid side to be used. (Remember inefficiencies though of ac > dc> ac).

So would I need canbus cables between the inverters? Or just from each inverter to the master battery?

As my generator is only 3kw, I was hoping to get a smaller sunsynk 3.6 even though it's not the same as my current. 5kw

I don't know the inverter myself but if they are able to be in parallel then it may be possible to do CAN to one inverter and then use the inverters link from that to the other inverter but I don't know how it would cope with the AC output not being the same.

Battery to each inverters CAN input should work but would depend on how the bms handles two sets of CAN messages from the inverter. Often it's only a message, like a ping, that lets the battery know their is an inverter there so the bms doesn't shut down. Again you would have to look at charge and discharge current setting.

If I were doing it I would use something like a Teensy to read and alter the CAN messages.

Look at my previous posts;

https://camelot-forum.co.uk/phpBB3/view ... 1548#p1548

Tinbum - I shall have a look through that forum link, but on first glance it seems to be well outside of my technical abilities!

TPage 59 in the manu has a section about parallel use

One thing that I was t aware of it to makes sure the firmware is the same on both machines!
Good luck and report back