First, ID your converter so you know what you are working with. Lithium capable or not. Charge Wizard or not. Open the circuit breaker panel door, inside you will find a white sticker with the model number of the converter. Mine for example PD4575K18LS8.
It is not Lithium ready but it does have the charge wizard which I use occasionally in manual mode to boost up my Lithium batteries charge if I know I'm going boondocking the next day or so.
Go to PD website and download your manual.
Next, you need to do an energy audit. Figure out what each appliance draws and add it up. This will tell you how many amps per day you use. From this you can size your batteries and solar panels.
Excellent article on energy audit (in watt hours)
https://docs.google.com/document/d/1...t?usp=drivesdk
You can do the same thing in Amp/hours but you will need to distinguish (convert) between AC and DC.
For example, most batteries are rated in Amp hours. your furnace uses about 12A dc. Worst case scenario, on a cold night
12A x 12 hours = 144Amp hours (Ah).
If you have a 100Ah battery it will be long dead before morning.
On top of that you should NOT run a FLA battery below 50%. It will shorten its life.
Lithium batteries you can go down to 10% safely.
How to find happiness with lithium batteries
https://www.solacity.com/how-to-keep...tteries-happy/
Will Prowse on YouTube has excellent tutorials.