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paul-campbell asked

Staging upgrades - temporary imbalances


330W panel, 40A MPPT, 2.4kWh 24V LFP battery, Multiplus 24/800.

Loads: Single "office" circuit running 100-200W of monitors, pcs, the usual junk.

Configured with the virtual switch on the multiplus to ignore AC and favour battery, It behaves much like it should, like a "house battery". On good days it stays off-grid overnight. On bad days it switches back to grid in the evenings.


990W panel, 40A+15A+15A MPPT per panel, 8kWh battery. Possibly a bigger or second multi.


I can't afford to do that all at once. Not without breaking the rules of no "non interest free" credit.

I want to start with the other 2 panels. The power output of which would be 0.4C on the batteries if the loads are off at peak sun. It might have to run that way for 3 months of summer before I can finance and source the batteries.

I intend to run all 3 panels on an MPPT controller individually. The panel site has progressive shading from both ends.

I am currently (pun?) looking at the Victron 100/15 MPPT units. I can "cap" the panel output to 26A or so by putting 2 of the new panels temporarily into a single 100/15.

Or... if they support current limiting I could probably balance the panels and battery far more nicely, so that i get the advantage of all 3 panels during lower light, but the current gets capped in "direct sun" to not hammer the battery.

I have seen other posts going into dynamic control and DVCC so that the inverter loads and battery net current can be taken into account and allow the inverter to make use of the full 990W while the battery charge is limited by the VE MPPTs.

3 months might be long enough to work without that. Not unless it's easy to inject via MQTT or similar interface under my control system.

3 months is too long to work with something like a temporary 250W heater load on the inverter to bleed panel power.

Options suggestions?

Additionally.... increasing inverter power from 800VA to maybe 2kVA... is the easiest option paralleling two multiplus's? Can a multi work in tandem with a more basic pheonix? Is chaining/tie-ing inverters together "dark siding" or is it supported yet?

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