Barry and Penny!
I'm fare from an expert on solar panels
But hear is my thought's so fare.
We have three 150 w panels in serie on the Arc, they are Turkish origin, and so fare we are very pleased with them. The two on the rail are from Sunbeam (Germany I believe) light weight panels also in serie, they give compared with the one on the arc fare less, they give on average 15% of my total solar energy but nominal it should give 31 % if everything equal, but they come more often in the shadow from the mizzen boom, We have two Victron Mppt regulators, and two Victron MPPT Control units, and I have the feeling that the MPPT for the rail panels "reads" what's coming in from the larger solar system and reduce out puts. I have the same issue with the two Battery charger I have, if I run them both when on shore power at the same time the smaller charger does not contribute after a few minutes. I guess it could be the same with more than one solar charger, especially if the charge rate for my batteries are high say +95%, but that is not a big deal, they looks giving OK when battery around 90%.
Our thoughts was to have two light weight panels on our Bimin in serie with the rail panels, but the canvas man told us it's not a good idea, as they will chafe, "destroy" they shape of the bimin and that it will collect moist between the panels and the canvas. So we decided not to put them there, but I'm considering to put them there anyway, to put chafe protection, the shape I'm less concerned about, then we have the issue with moister, but our Bimini is not very large and to replace it now and then is not a major cost.
Paul on S/Y Kerpa SM#259 en route to Sicily