The calculator allows up to 130% over-paneling by default. But this setting can be overridden. Victron allows over-paneling provided the limits I mentioned before are not exceeded. For me, that will be 137%. I don’t cross any Victron line.
How much over-paneling is too much? I remember vividly reading a Victron blog about it, which suggests I will be fine.
Of course, there can be a lot of waste involved. How much waste? This depends on your environment and use case. In my case, panels being cheap, I thought I would over-panel as long as the limits allow for those cloudy days.
Yes. I can see no reason why the inverter cannot be built with inherent protection from overpanelling, the only limits should be the Vmax, Imax and Wmax the inverter can withstand/tolerate. All the inverter has to do is restrict its input current which will cause the input voltage to rise thus reducing the current and thus the dissipation in the inverter. I would have to go back and re-read the manual for the precise wording, but I think they do specify a max panel power (nominal) which is pretty well equivalent to the rated power. Whether that is a real life limitation or caution, I cannot say. If I were designing it, it would be as bomb-proof as I could make it given that is so trivially easy.