We spent the month of July in the North Channel in Northern Lake Huron north of the 45th parallel.  We logged the output of our top-of-pole mounted 85 watt Kyocera solar panel and our daily power consumption.  It was an unusually cloudy July.  Here are some statistics.

Weather
Mostly cloudy      7 days
Partly cloudy       8 days
Partly sunny        8 days
Mostly sunny       7 days

Power Generation
Maximum power produced in a day was 38 amp-hours
Minimum power produced in a day was 12 amp-hours
Average power produced per day for the 30 day period was 25 amp-hours

Power Consumption
Average power consumed for the 30 day period was 46 amp-hours

Our travel pattern was to stay at anchor for 2-3 days and then motor/sail to another anchorage.  We connected to shore power one night.  While we ran a power deficit of 21 amp-hours per day while at anchor, our high output 75 watt alternator quickly replenished our batteries on our travel days.

We ran our refrigeration/freezer every day as well as our computer (chart plotting) and autopilot when underway.  We found the combination of our 85 watt panel and our 75 watt alternator provided us with ample power for the trip.