it's a near impossibility to site a solar panel on a sailboat that is entirely shade free for the entire length of the day
That's probably true of a reasonably-sized monohull, but Ocelot is a cat. Setup is 4x 120W Kyocera panels out over the dinghy davits (we have a lot of room back there and it doubles as a shade for the rear of the cockpit). You can read a bit more about them here (photos are outdated in general but we haven't modified the array since they were taken): http://svocelot.com/Ocelot/mod...
Having the panels so far aft and so high provided some protection from salt spray (enough that they don't need cleaning after any but the roughest passages, the kind where the whole boat needs a good rain rinse) and also kept them out of the line of most of our shadows. If the sun sets or rises directly in line with the panels and mast, then yes, we'll lose that panel, but this can often be remedied by running the boom out to one side (tied down with the jibe preventer) and letting the (relatively huge) sail protector swing the boat a few degrees away from pointing dead into the wind. By anywhere close to the hours when the sun is at full power, even our slightly-raked mast just isn't far enough back to shade the panels. (As a side note, it occurs to me that this may explain why the ramp up to full power took longer in the morning than evening; if the easterly winds meant the panels were occasionally shaded in the early morning, we'd only have 3/4 the nominal power production for that much insolation.)
As for angle, that definitely cost us some power - our panels are very much immobile, aside from changing the orientation of the entire boat - but I'm not actually sure how much. Even at 60 degrees off apex, which is pretty late in the day (assuming you're right under the sun's path, within +/- 60 degrees is 1/3 of the day, or 8 hours), you still get 50% of the insolation you would get at apex, atmospheric losses aside. That's certainly significant losses, and it drops off sharply after that, but the middle hours of the day are not severely affected.
By the way, nice site! I'll have to ask my folks if they ever ran into Animation coming up the Aus coast. Alternatively, do you know S/V Vamp? Good friends of ours. I'm sorry you posted as AC but I may ping you by email.