The amount of power needed while cruising depends on many factors including the energy used by appliances and lighting, the output of the engine alternator, the climate and the length of time away from shore power. These and other factors will determine the amount of solar power and thus size of the solar panel(s) you may need. Working with Ed Foster of foster-wills.com, we have developed a worksheet to assist you in inventorying your on board power generation and consumption and estimating you solar power requirement. Print out our Solar Power Calculation Worksheet and use it as a guide to figuring out your power generation requirement. From this you can get an idea of what your solar panel options might be. Hope it helps!
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.
Mostly cloudy 7 days
Partly cloudy 8 days
Partly sunny 8 days
Mostly sunny 7 days
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
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.
Solar panels provide an excellent solution for obtaining the electrical power needed to support on-board electrical systems. They are quiet, require little maintenance and are reliable.