Thanks for this post and everyone's explanation of MPPT. I too in my mind use the analogy that the extra voltage is "converted" (yes I know this is NOT the right terminolgy or process that happens with MPTT) but its easier to think of that way for people who are not highly knowledgeable in MPTT or even the whole PV process. Some might say 'well they shouldn't be messing around with solar' which I suppose is a fair point. At the same time its so easy now with companies providing small PV systems that are turn key that your average Joe who understands very basic electronics can slap together safely and reap the benefits. I have a degree in computer engineering (essentially an electrical engineering degree but with more programming classes). I don't claim to be any kind of expert, in fact you will see all my posts are in the 'Beginners' section of this forum.
While in my mind I used the incorrect analogy that MPPT takes surplus solar engery in the for of volts and "converts" it into amps that the SCC passes down to your battery/load. That made it easier for me to just make sense of it at first. Knowing that it acts as DC-DC converter / Buck converter (with other technology as well) may make it a bit difficult for someone to grasp that its not "converting engery from your PV array into extra amps from "unused" volts.
I can see why its easy for someone to think that, asssuming 100% efficiency lets say you have 4 panels 100 watts each and each panel produces 5 amps and a Voc of 20volts. You know already that the limit of the power that can be produced is simply # of panels multiplied by their wattage rating. In our case 400 watts is the max power possible. Then people start looking at series and parallel panel combinations and can easily be led to coming to the conclusion that 'hey if my panels are all in series' I have 20v + 20v + 20v + 20v = 80v at 5 amps (80v x 5a) = 400 watts. Then they look at their MPPT SCC and they see their battery on a perfect sunny day is pulling 10amps! Woah! What?! But my panels in series only put out 5 amps and I'm seeing 10 on my solar charge controller, why? That's were imho, I think the people who don't understand mppt correctly want to think well its taking that "extra voltage" since I only have a 12V battery I'm charging and "converting it volts into more amps". Then they get further confused if they do a 2S2P configuration (40x10amps) = 400 watts. But this time there's no "extra" current.
I think once they grasp the concept it then becomes one of those things you think to yourself (wow I am embarassed I didn't get it) but thats ok, you are asking and learning! Then you start finding yourself asking well when do I need to do parallel connections, what's the pros/cons to such a mix of series/parallel if at the end of the day MPPT handles it for you. Now we have to step out of our perfect 100% perfect world and into the real world to learn as to why/how/when to do such combinations. That's a whole different story. Sorry to revive a dead post. But I stumbled across is as I was looking to get a deeper technical understanding of MPTT myself. Any day now I have 12 panels arriving to add to the fun. My 4x 100watt panels have been great but I want to speed up charging of some big battery banks I built.
