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isavednokat asked

Two independent grid tied systems to send excess power to each other instead of out to the grid

I have two adjacent properties about 40m apart running (more or less) twin systems each based on a Multiplus II 10kVA, Cerbo GX, solar charge controllers, a bank of LiFePO4 batteries and some legacy A/C coupled generation as well. For a bunch of reasons I don't think it's practical to get rid of one meter connection and merge the systems but it would be so much more efficient if I could have the two battery banks balance with each other and absorb any excesses first before losing any residue to the grid. Is there some gadget that could do this? I envision possibly even a new product that does some kind of isolated DC-DC connection between the two DC buses whilst appearing to each side as another charge controller that can potentially source or sink power. But I'm really open to any ideas here...anyone got at least a starting point for me?

Multiplus-IIbattery charginggriddc system
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isavednokat answered ·

This feels more like a question for Victron staff directly given that it postulates a possible new product...any chance of someone there commenting? Not only is energy lost to the grid sometimes, which is not compensated for here in johannesburg, but the bigger problem is that solar charge controllers are throttled back when their adjacent battery bank is full whilst I may still have lots of battery space available on the other property thereby losing significant generation.

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nickdb answered ·

A niche case like this is unlikely to be commercially viable as a product, not to mention that physics makes it complicated.

You'd be better off asking this in modifications, but remember, as per guidelines, this is a community site, not a direct channel to staff.



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isavednokat avatar image isavednokat commented ·
@nickdb I think the concept of a power source/sink option that can integrate to a DC bus and all the Victron control mechanisms and software linked to that bus could have very much wider applicability than just my situation...it becomes a generalised way of integrating any other source of energy or interfacing any other storage without it having to exactly match in specification...tweak the voltage higher and power flows in, tweak it lower and power flows out...internally it converts between two DC voltages appropriate to its interactions with the two buses it connects to. For example each of my systems is now strictly limited as to how much storage there can be by physical limitations of space and the requirement of keeping connections the same length and availability of the exact model of battery and the abillity to keep all units operating under the same BMS so that they appear as a single coordinated battery to the Victron setup - with something like this I could dedicate another space close by to a whole new set of storage and integrate it, even years down the line from the original system design.
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