I have a 1990 Macgregor 26s with 100Ah of 24v LiFePO4 batteries, a 480 watt solar array, and a little-bit-less-than-2HP torquedo like (Haswing Protruar) electric motor. My boat is significantly less displacement than a Hunter 27e, (probably ~3700-4000 lbs loaded with me and the Mrs. and the 30 gallon water tank and the 30 pack of beer in the refrigerator) but I do have some experience with an electric/solar boat of similar length so perhaps my thoughts are relevant. And, I am an extra class ham radio operator so I know a little bit about electricity... (Though not much, I am also a dumb redneck.)
That Hunter can probably realistically motor 8-10 hours at *cruising* speed in flat water without a problem. But what is cruising speed? I define cruising speed as the point of most reasonable amount of power expended for the most reasonable amount of speed from the vessel. Tradeoff. If you have unlimited power cruising speed becomes hull speed.
Down here in reality, with that boat, though, it's probably more like 4 knots.
My 480 watts of solar will develop about 13-14 amps @ 27volts (about my float voltage) in PERFECT conditions (which only exist about 7 hours a day, average, at our latitude, with no clouds.)
13-14 amps (so, 360ish watts) will push my light boat at about 3.2-3.4 knots with no wind. Great for my local lake. If I draw from the battery and push it to max (about 45 amps/1250 watts) I get about 4.8 knots with no wind, or about 2.5 knots into a 20 knot headwind. The power required to push a boat increases exponentially with speed. A figure I heard cited which seems to hold true is double the power for every knot of speed.
To compare, my Yamaha 9.9 high thrust will cruise (~2400rpm) at about 4.8-5 knots. At that rpm I figure it's putting out 2.5 hp. Hull speed is 6.5.. I've had it to 6.2 with the Yamaha..
What it comes down to is that in perfect conditions you can make headway (if you're patient) with very little power. But most people are not willing or able to put enough solar to make moderate range cruising a possibility. The charge INefficiency of lead-acid batteries compounds the effect. The top 20% of a lead acid battery's charge is almost unobtainable on a working boat by solar due to the idiosyncrasies of the chemistry. Solar can float it.. but solar will never bulk AND absorb with the amount of insolation (Again, by lattitude, but Arizona/Californa = ~7 hours...) available. Lithium Iron Phosphate has a chance because of the charge efficiency, though, but it's costly and requires a whole lot more money or active management than most people are willing to put into it. NOW, add windage from your panels, a 30 knot headwind and ebb tide into safe harbor 10 miles away during a freak storm where clouds are blocking the sun and nightfall is an hour away.... Either you have a genset you can start or you are going to have one hell of a rough survival sail with dead batteries, no nav lights, no chart plotter, and no shipboard VHF.
Funny thing is I am a proponent of the technology LOL.. because a BIG solar array, smart power management, high efficiency batteries and your sails give you a lot of possibilities (my fridge always keeps my beer 34degF, no need to ever fire up a motor to charge).. but be prepared to be VERY cautious and have backup plans for your backup plans.
Just some thoughts...I'm done with my scotch now, good luck.
. It's at Newport Beach CA. BTW love our Potter, but it is a bit small for over night.