I've bought a second hand motorhome with two 100W solar panels fitted. It has two Bluesolar 75/15 controllers fitted and I want to upgrade to Smartsolar. I don't understand why the previous installer fitted two as one should handle 220W of solar panels according to the datasheet. Is there any good reason why I cannot just combined the panels and use one 15A controller? If I can't then presumably one 20A controller would be perfect in preference to gain two controllers.