I'd like to have (2) 100W solar panels on the roof of a van. Is there a simple solution to have (2) extra 100 W panels to plug in when parked? Would the charge controller just need to be sized for 400W? Is there any kind of simple disconnect system available to add the 200 W in series to the panels?
Series not realy (somebody might make a connector to make this work), parallel sure trivially easy. I use a pair of MC4 connectors behind the skirting, just connect up the portables once I'm at camp. As long as it's within the specs of your MPPT should be fine.
For a series connection, you need to short out the connector you use to plug in the extra panels. This could be done by inserting a dummy plug with the pins shorted, but there's an easier way:
Connect a schottky diode between the pins of the connector or use MC4 Y cables and Diode mounted in an MC4 housing. The diode orientation needs to be such that the current from the roof mounted panels flows through the diode.
