When our supplier told me they had a new high output marine solar panel that was flexible I was skeptical. The specifications seemed just to good to be true. So I ordered some to test. Well, I was pleasantly surprised.
These panels are very well constructed and they have a power generation comparable to our hard panels. These panels can be flexed to 30 degrees so can conform to most boat curved surfaces. The 100+ watt panels have an electrical box on the front (not shown in the picture) which contains two blocking diodes. The 50 watt panel has one blocking diode. The base material is very sturdy and strong. Each panel has grommets for attaching the panel.
I have tested the output of these panels under various weather conditions and their susceptibility to shading. Below is a quick comparison of output of our three mid-range panels laying flat at mid day on a mostly sunny day measured with a meter:
Flexible 100 watt Rigid 105 watt Rigid 100 watt
Monocrystalline Monocrystalline Polycrystalline
Short Circuit Current (Isc) 5.48 amps 5.50 amps 5.26 amps
Open Circuit Voltage (Voc) 19.2 volts 19.7 volts 20.5 volts
Computed Power (not rated power) 105 watts 108 watts 108 watts
Additional information is available on our solar panel page.
At other places on this blog and on our web site we talk about how to determine the size of solar panel (how many watts) you will need to meet you power consumption requirements. Once you know your panel size requirement there are some things to consider in selecting a solar panel.
Panel Type - There are many articles written on the two types of solar panels; monocrystalline and polycrystalline. Monocrystalline panels are made up of single crystal silicon wafers. Polycrystalline panels are made up of silicon that has a multiple crystalline structure. There are pros and cons to each type of panel. Monocrystalline panels have a higher output per square inch in direct sun but are very sensitive to shading and output will degrade faster on cloudy days. Polycrystalline panels are not as sensitive to being shaded and output will not degrade as much on cloudy days. At CMP we offer both a polycrystalline and a monocrystalline panel.
Panel Crystal Quality - Because we have a confined space on our boats, we need to have the maximum output per square inch from our solar panels. The quality of the silicon crystals used to make the panel is a key factor in determining the panel output. Crystals are passed under a fixed light and graded as to their output (1-10). Grades are grouped into classes. Class A crystals are grades 8-10, Class B crystals are grades 4-7 and so on. Crystal quality follows a bell curve; there are many more Class B crystals than Class A. We at CMP specify only the best Class A crystals for use in our panels. Less expensive Class B and C panels are often used on land based solar farms where space is not an issue.
Panel Shape - The largest market for solar panels is commercial applications where many many panels are mounted on a roof or in a field. These panels are usually rectangular in shape often twice as long as wide. This shape is often not ideal for marine application. Often a more square shape is preferable, especially for pole mounting.
Choosing the right panel for your needs will require study and/or discussion with panel experts.
The weather for our cruise in the North Channel of Lake Huron this year was excellent. It was warmer and sunnier than last year. Our Kyocera 85 watt solar panel performed very well. The following are some statistics:
Days cruising: 22 days
Max power generation: 40 amp-hours
Min power generation: 13 amp-hours
Average power produced per day: 35 amp-hours
Average power consumed per day: 51 amp-hours
Our primary use of power was for the refrigerator/freezer. We ran a power deficit each day of about 16 amp-hours at anchor but with our 360 amp-hour battery bank, this not a problem. Moving on every 4 days or so gave the 75 amp alternator plenty of time to bring the batteries back up to charge.
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.
Thomas Trimmer has been cruising with his Ericson 38 sailboat on the Great Lakes for over 20 years. He has pioneered the use of solar energy for wilderness cruising. He is continually designing and building equipment to simplify and enhance the cruising experience.