Can someone explain why you can't add shittons of panels to a small inverter to get as much power as possible even during cloudy weather, and then have an automatically adjusting resistor to keep the inverter from getting too much power during bright days? You'd think getting rid of excess energy would be the simplest possible thing to do, but everyone seems to treat it as impossible.

The peak of this was a discussion with a solar system seller, who only admitted that any kind of adjustment at all was possible when I had argued it down to an automatic curtain that physically blocks part of the panels when the current is getting too high. At least that would work apparently, but why on earth we can't simply add a resistor to the wire?