I have a new, 2026 5th wheel RV that has one, 200-watt solar panel, a 75 15 solar controller that is charging two lead acid batteries. I’m going to swap out the batteries with two 100Ah lithium batteries. I was also going to swap out the controller with a Victron 100 30 controller to hopefully charge the batteries quicker and just in case I decide to add another solar panel.
Is it just a matter of plug and play with the new controller or do I need to add anything else? (I have a switch on the inverter to convert to lithium)
You should review your wire sizes & protection if you’re changing max current.
Doubt the controller is the limiting factor on a 200W panel. Larger panel might help, as long as you’re under the PV voltage & current limitations in the manual the controller will limit charge to 15A. It might be more economical when adding another panel to use another 75/15. Helps with shading too.
Paul is correct regarding the controller not increasing your charging current as well as the importance of confirming proper wire and circuit protection.
The amp rating on the controller is not a number indicating what it will charge at but what it is capable of depending on its input(the panels). Your 200 what panel can only produce so much. And 15 amps is the very high end what it can possibly produce. There are, perhaps, rare circumstances where the 200 watt panel, combined with an MPPT may produce more than 15 amps, in which case a 20 or 30 amp controller would be able to utilize the surplus. But this scenario would be rare. In short, upgrading the MPPT will not charge faster.
I concur with @MiPaul that your best time and money spent would be to add another panel and MPPT. Or if it is more practical, remove the existing panel and replace it with a larger one, along with a bigger MPPT. Again, confirming wire size and circuit protection is sufficient.
The larger picture here, if you don’t mind me saying, is insuring all your other charging sources are configured to charge the LFP batteries. These sources would be your converter/charger and however your tow vehicle’s alternator are charging the LFPs. When your refer to your “switch on the inverter to convert to lithium” do you mean the onboard converter or do you actually have an inverter/charger? Either way, yes, you will need to change the charging profile to lithium on either one.
As far as the MPPT goes, it is not quite plug and play. You will need to get into the settings and change it to a LFP charging profile using Victron Connect.