I have a Multi RS solar with 16kwh battery and cerbo gx. I am thinking of buying a mppt RS 450-100 because the multi rs solar’s mppts only use 12A of solar input current. The rs 450-100 can use 18A of solar input current. My panels are around 14A impp, so i will loose some power because of clipping during the best sunny days.
I am also interested by the full galvanic isolation provided by the multi rs solar and rs 450-100 combination (of course in this configuration i will not use the integrated mppts of the multi rs solar)
I also assume the multi rs solar will last longer because there will be no heat generation from the integrated mppts
I am planning to add more panels with micro inverters in the futur on the ac out of the inverter (2 kwp or 3 kwp at most), the multi rs solar is limited to 100A of AC/DC charging , so with an additional rs450-100 i will have more charging power.
Do you think it’s worth the cost? ? Will the multi rs solar work properly with its mppts being left unused?
You already own the MultiRS, correct? So you plan to spend another what, 900 bucks, in order to be able to use an additional 2A at the very top of the power curve.
Since you already have the MultiRS and a Cerbo, i guess you also set up VRM. In the advanced tab you can configure a graph to show you the PV current. So you can take a look at how many times and for how long that 12A limit is actually being hit. You can now imagine the curve continuing, completing the arc. Is that sliver of energy worth 900 bucks to you? Maybe it is, for me it would not be.
Yes
Ok thats an argument. But you could also use both the MPPTs of the MultiRS and the extra RS450 instead of again spending money on micro inverters.
One thing to also keep in mind is conversion efficiency, or conversion losses. By using the internal MPPTs you get a higher efficiency on converting PV to AC voltage, since only the internal DC bus is used. By using an external MPPT you are converting PV to 48VDC to charge the battery, then 48VDC to the internal DC bus in the MultiRS, then create AC out of that, For energy that goes into the battery it doesnt matter since the double conversion happens either way, but direct usage of AC power is more efficient by using the internal MPPTs of the MultiRS.
Same for using micro inverters. If you can directly use the energy they produce then thats fairly efficient. But if you convert PV voltage to AC in the micro, then AC to internal DC bus and then to 48VDC in the MultiRS to charge the battery, only to then reverse that again, its quite inefficient.