If you have 2 panels now, you can make the system work with 2s to start.
To add on, don't need same model, just similar Voc & Vmp. A different 2 panels wires 2s (or lower voltage panels wired 3s or 4s) that come to within 10% of same voltage will work. Shop locally.
If all panels oriented toward sun at the same time, current from the two strings adds. I think the panels put out 14A and your equipment specifies 15A, so can't do that.
If you mounted panels standing on edge facing West, and added panels back to back facing East, they would put out power different times, morning and evening, so never over 15A. But at Noon, sun hits the edge and makes zero power.
If you tilted one string 30 degrees off vertical, and the other string facing other direction 30 degrees off vertical for 60 degrees between the two strings, they would present pretty much same area to the sun all day. Should still be 15A max, but more hours of production.
I have deliveries to freight terminal, save cost of last mile with liftgate truck. I go get them with my pickup.
I also use smaller panels, like up to 370W, 45 lbs, 3.5' x 5', easier for me to handle alone.
Yours are 70 lbs and almost the size of a 4x8 sheet.
