I purchased at SanTan solar. They have more than one location, bought mine in Gilbert, AZ
I have two systems at this time. A 12vdc system, and a 48volt system.
Both systems have panel voltage at 67 volts. That voltage is only required on the 48volt system due to the the 53 volt charging requirements of the rack mount lithium battery being used. I am not a fan of lithium but salvaged, helped make my decision. Still I wonder about my choice.
The 12vdc batteries (all 400ah of them) are Northstar blue+. The inexpensive PowMr controllers convert the power from the panels close to the batteries.
I made the choice for multiple controllers for duplicate systems design. A decision I have not regretted! Had it not been that way my refrigerator would have been full of spoiled food on a couple of occasions.
MPPT controllers are required to use a "24" volt solar panel for 12vdc systems. The house panels I use are 3x volts likely 35 volts. This they would call a 24volt panel. 19 volts would be what they call a 12vdc panel. The choice has only to do with the fact a 19 volt panel will not charge a 24volt battery, yes it can in a series connected panel array. It surprises me how some people in the industry are so poorly educated in their field they don't understand what works. Anyway, as long as the controllers will handle the peak voltage of the panel(s), the higher the voltage to the controller, the smaller the wire can be. For an RV my system is quite large. Even still, my wires are 10 awg, excepting those wires running from the cargo trailer, those are 6awg.
I tell people 500w is a minimum system. Not because you can't do with less. However when people see what I do, they start buying stuff I use and say " how can you, and I can't ".
Here is an example:
I have a chest freezer, an apartment size refrigerator. I make my espresso in the morning, and dilute it to taste with water I heat with an electric tea kettle. I use an instapot to precooked meals every 4 days or so, and warm them with an electric rice cooker.
I have a lady friend who I am showing the ropes, that is plugged into my rig till we have her setup with her own system.
When something needs modification I use my table saw and planner as needed.
I do have a poor boy generator should my batteries take to much of a hit. But running it is more of a maintenance thing.
Hope that dissertation is useful!!!