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I am configuring a new system for an off-grid installation and I am not sure which device is more suitable for my case. I see that Multiplus I is 70-100A but Multiplus II is 70-50A.
I want to connect it to a solar panel array of 4800W and 4xPylontech 2,4kW batteries, plus the Victron MPPT 250V100A and the Victron Color Control GX at 48V + the additional genset in case batteries drop below certain level. Any suggestions? Thanks
Hi @tpwchr,
some thoughts
Given that you have a 70 amp charger in both, I am not sure that it matters. Max charge current from 250V genset will be 1/5th of this ... 14 amps, so having a 50 amp transfer switch is never going to be an issue if you are off-grid (unless you have big additional loads that you will only run when the genset is running).
I would make sure that the genset is 'compatible' with the inverter. Check out https://www.victronenergy.com/live/multiplus_faq before you buy.
Consider if you will manually or automatically start the genset and confirm the stop/start interface compatibility.
MMPT 250V100A - 250V will mean 4 parallel strings of 6 panels (assuming 24x200W panels)? Peak current could be close to 40amps Keep an eye on cable sizing, particularly if the panels are a significant distance from batteries. Keep any potential shading to a single string if possible to maximize power.
If you need to power large inductive loads such as bore/well pumps, be really careful to ensure that the inverter can handle their startup current requirements which could be 4-6 times their running requirements.
hope this helps,
Ron
Hi @rrroonn, thanks for answering. So why would it only charge at 1/5th of it? I would have thought that it would charge at 50A*48V=2400Wh. The generator is activated automatically when the battery drops to an specified level through the inverter.
Regarding the solar panels, I thought of 16x400Wp in 4 parallels of 4 series (199,2V41,44A).
Fortunately I dont have any of those special loads, just a normal house. Thanks!
Hi @tpwchr For me the key consideration would be the slightly lower power consumption of the newer MPII model especially if you are 100% off-grid, it is also much lighter and just be mindful that the first generation MPIIs had m6 battery connectors vs M8 on the latest. Otherwise a no brainer given the processor and some upgrades to the boards, connectors etc. My MPII first gen has now been running almost two years completely unattended 6000miles away serving my holiday home I have been unable to visit ;)
Thanks for your reply @ejrossouw I made the choice and its going to be the MPII even though it would charge the batteries 50% slower than the MPI because of the 50A instead of 100A. Hopefully wont need the Genset too often. What do you think of the rest of my solar config?
The chargers are 70A DC on both versions and that is DC, so the 100A AC transfer switch is irrelevant. It will max out at about 15A on AC.
I cannot comment much without knowing more about the loads, peaks etc., but at a very high level under ideal circumstances, if there are no loads the batteries can easily be charged in about 2-3 hrs from 80% DOD. Just make sure the generator is powerful enough to handle the charging loads when it is required.
Another of my installations charges a 189Ah LG Chem RESU10 at 35A in under three hrs from 74% DOD to 95% (no solar though, but your MMPT should be even better being DC to DC) Of course it will depend on solar yield at the time as well as the loads which will be served first and then the battery will be charged.
Hope this helps.
To be CLEAR The difference between the two models is the AC transfer current is 100amps on the multiplus or 50amps on the multiplus II so if the output from your generator is NEVER going to exceed 50 amps I would go for the MP II as its the lattest tech and as others say has lower no load standby power.
In reatlity you may never get that low in loads so pick the one that you may grow into . I suspect you will never get near the 50amp maximum so the MP II would be my choice
