I currently run my multiplus ii 48/10000 in off grid mode. During high demand times i often see the loads reaching towards 8kw which is the inverters limit.
Im thinking of getting a second inverter, and thinking of a multiplus II 48/5000 to run in parallel with my existing 10kva, but can this be done, being they are both different powers, or would i need to buy another 10kva version, to balance them? Alternatively i could do what Andy did on "off grid garage "(youtube) he uses his Phoenix inverter as a generator which kickes in if his loads reach the limit of his multiplus, but my concerns are that if i suddenly peak over 8kw, that the generator power (Phoenix inverter) may take too long to add its power to the load, and my multiplus could trip off before being load assisted.
Any ideas?
For a parallel setup, both units need to be identical and even recommended to be of the same hardware revision, and of course same software revision
Now, this is a bit redneck and I’m assuming that they wouldn’t let the magic smoke out of each other trying to sync… but I suppose you could run a 5kva feeding a “shore power/grid” input to the 10kva, with an input current limit on the 10kva set to accommodate the 5kva input limit. The system would run primarily on the 5kva unit, then the 10kva would kick into power assist and provide another 10kva
As for the generator config, the multiplus can handle some momentary overload as long as it is not thermally stressed. That may work as long as you can get the generator online fast enough, from what I’ve read the 10kva can handle an overload condition up to several minutes of course assuming conditions remain stable and thermal protection isn’t an issue
The trouble with connecting a 2nd inverter onto the ac output on my 10kva inverter is that i currently have a 3kw solar inverter already connected to it.
So what would be the best connection method while still keeping my 3kw solar inverter connected to assist my mppts to charge the batteries?
I guess just the same as I had mentioned (again, assuming this configuration will work stacking inverters like this and then being able to sync up to each other)
Solar3kw-mp5kva-mp10kva
The solar would be the primary, during light/no load the power passes through the multiplus’s transfer switch and off to your panel
As demand increases up to the solar inverters limit, the 5kva would start power assisting, as the 5kva reaches its limit the 10kva will start power assisting.
Sounds good in theory I guess. In the perfect world you would just get another 48/10000 and parallel them properly but that doesn’t sound near as fun!
So basically i can connect a 5kva inverter and a 3kw silar inverter in parallel onto my 10kva ac1 out terminals, so in effect all 3 inverters outputs ate in parallel to my consumer unit?
If so theres one problem, the 5kva inverter would want to go into charging mode and charge the batteries ( like the 3kw solar inverter already does.)
But that will just contiuous cycle the batteries which i dont want .
This is the joy of having absolutely no clue what kind of setup you have installed exactly!
So your pv feeds mppts as well as a solar charger/inverter correct? The combination of them is used to charge batteries and the 48/10000 is not set up to charge? How is your generator tied into this?
The multiplus charger can be turned off if you wish to use other means of charging
You can use ESS. I do this when off-grid with 2 smaller inverters in the shed. I have a 5000 multi with critical loads and the AC in of the 2x shed multis are wired to the consumer unit. I have a shelly EM in the consumer unit and use node-red to check the power and when it’s a certain value enable exports. The 2 units in the shed are 1200va ea give me 7400va total. I need to disable the internal charger or they will charge from each other. It’s a very satisfying project.
They are normally grid-connected and I have another SD card for the RPIs in the shed with a different configuration for off-grid when I lose power.
In my case i was not granted dno permission to connect my mp2 to the grid because of its size10kva, and i already have a g98 and export 3kw from my solar inverter (an array of 14 enphase microinverters)
And get paid a FIT.
The current way its configured is with an automatic transfer switch which is triggered by the mp2 to send enphase power to the loads, which in turn also charges the excess into the batteries via ac1 out, then when soc reaches 96% the transfer switch isolates the enphase system from the off grid side and switches it onto the grid side to export excess.
So if i were to connect another inverter to power assist onto the ac1 out, it would be parallel to the enphase system and will probably start charging the batteries with the batteries own power.
And the “ac in” is via a contactor connected to the grid, so when im on a low soc and cheap rate starts, the contactor closes and the mp2 becomes a battery charger from the grid. So i cant connect a 2nd inverter as a generator to the ac in. So im feeling stuck not knowing the best solution to power assist if loads get too high.
That’s not too dissimilar to mine I have AC PV inverters on AC in and MPPT DC charging. The other 2 multis are connected to the consumer unit on AC out. They work just like your microinverters when the grid is out. It wasn’t easy but I have the 2 AC out connected multis supporting the 5000va using ESS.
I found a video of someone using ESS to combine 2 different units. Mine is done entirely differently but you can see in the video a Multi in a camper connected to a Quatro in the House. This is not an example of how to do it just that it works.
I may have missed it, but depending on the size, frequency and duration of the overload the Multi can handle short periods of higher loads. Question is more of whether the batteries can handle such demands. Easiest is to buy a 15kVA (12kW) and sell the 10kVA.