I admit I was wrong assuming the MPPT like a PVM output is the same as input voltage. I have never considered wasting money on a MPPT, so I wasn't up on it. I plan to use an PVM since they are less expensive and will do the job more efficiently. Now if you want to add an extra panel, go ahead. I (we) have to first out how much power we actually need to size everything properly. Then go with good products and keep them as small as necessary... good batteries, good charger, good inverter. The key is balance. I might make sense if you can afford them, to have more PV panel than you need, but not so much on everything else. I plan to figure what will run on a modified SW Inverter before starting. I continue to learn and am rereading all that HandyBob (https://handybobsolar.wordpress.com/
) has to say. He points out that most solar pros (even the big dogs) have an agenda and it isn't getting you the right system for you needs. For instance, did you know that the biggest issue with batteries is that the equipment we are being sold isn't charging them fully. We who have actually camp outside a resort might start the evening on batteries half (or less) charged; this is causing them to not last as long as they should. Staying the night in a Walmart parking lot isn't boondocking.