Hello everyone. Would this be possible? What would be the main problems?
I'm trying not to despise my old installation by combining it with the new one I'm going to install. I have thought about this solution. At first glance it doesn't seem very far-fetched to me.
Don't be hard on me.
Pretty sure it's not supported by victron but i'll answer the concerns i spotted.
Main one is around does multiplus 1 have ACOUT1 and ACOUT2 like a multiplus II does.
If it does my concern was going to be what if the grid went down and Mutliplus I ACOUT1 was wired in multplus II ACIN then there's a risk that mutliplus II continues to export power as the multiplus-I has setup a micro grid.
Which is fine unless the OPSZ cells and LiFePO4 cells are full then you have a situation where fonius is pumping out power and multiplus II is exporting power but this has no where to go if OPSZ cells are also full. You'd need to tell fronius to turn off via the multiplus i in this scenario (you'd have to make something yourself).
Solution 1: to wire ACOUT2 of multiplus i into multplus II's ACIN as ACOUT2 will go off when grid goes down preventing multiplus II exporting power. The only issue then is if grid is off for a long time the OPSZ could be full and LiFePO4 could be empty as you wont be able to transfer between the two if the grid is down. (this is assuming loads are wired off the multplus ii).
Solution 2: disable exporting on multiplus ii (however if lifepo4 often fill up before OPSZ you may lose some energy where fronius is throttled back even if OPZS isnt full).
First of all, thank you very much for your response. Indeed, the Multiplus I has two outputs. One of them is only for critical loads, this output is the one I intend to use. Regarding your concern, I forgot to mention that the ESS where the multiplus II is installed, zero feed-in is configured so that the energy does not circulate in the opposite direction towards the “grid” emulated by the multiplus I. Of the proposed solutions, I prefer the second. At no time do I don't intend to feed in the excess electricity. Simply configure the system to take advantage of the storage of the OPZs batteries and be able to start the multiplus II in case of no grid (very common), discharged batteries or no sunlight. The opzs have their own recharging system and would only be used in very adverse weather conditions (rare here). In summary, I think you would agree with me in stating that this installation is possible as long as the multiplus II ESS is configured not to discharge into the network. This configuration is the current one, in the typical AC-coupling configuration.
There's probably a better solution but I cant think of one without needing custom relays/code to try control the multiplus I.
I imagine the official answer is change wiring of loads to be split. Say multiplus 1 does 30% of loads multiplus ii does the rest, and split the loads across the two.
And then manually balance the two somehow. However I imagine if everything is allready wired in place then this is way more of a headache than the above.
Your exposition is correct. Splitting the loads is a very expensive solution. Another solution is to configure the two installations in parallel by placing a transfer switch on the outputs, whether manual or automatic, and being able to choose between the two energy sources, preventing them from being connected at the same time. Let's think that the multiplus I installation would be used as a generator. all the best
