We tested our new 150 watt polycrystalline solar panel on a 35 day cruise in the North Channel area of Northern Lake Huron.  This panel was equipped with the prototype of our solar water heating system which will be addressed in another blog entry. The solar panel was mounted on our pole mounting system and was rotated toward the sun The boat equipment and cruising pattern was essentially the same as last year (See prior blog entries).  We were powering a freezer/refrigeration system, instruments, laptop computer, radios, autopilot, windlass and LED lights. Data was gathered using the remote display on our EP 10 amp dual output solar controller.  The solar panel performance met our expectations.  Our house battery bank consists of three 120 amp hour flooded batteries.  
Both battery banks were usually fully charged by 2 PM when at anchor and on mostly sunny days so we often had excess power. 

Data comparing the performance of the 150 watt solar panel with our 140 and 160 watt panels is presented below.

Average amp hours per day produced under various conditions:

                                                       150 Watt poly  140 Watt, poly    160 Watt, mono    160 Watt, mono
                                                                2015             2012                   2013                    2014

Overall average output per day         49 amp hours    53 amp hours       48 amp hours          48 amp hours

Sunny days                                                 60                 69                        71                        69
Mostly sunny days                                       56                 50                       50                         56 
Mostly cloudy days                                      36                 35                        37                        39
Cloudy days                                                22                 32                        28                        20
                    
Avg. Output on days at anchor                     60                  62                        61                       51
Avg. Output when engine was used              42                  43                        44                       45
 
 Min amp hrs for a day                                 4                   27                        28                        4
 Max amp hrs for a day                               84                   74                        77                      76

Max amps output                                      11.8 amps      10.5 amps            11.5 amps           11.4 amps

This data is intended to provide a general idea of what to expect from the solar panels under various conditions.  The two primary variables are the amount of sunshine and the running of the engine (the alternator charges the batteries so the controller shuts off power from the panels).   Because the panel was equipped with a water heat collector on the back, it may have run hotter on sunny days when the water circulation pump wasn't run thus degrading the performance by up to 10%.The average panel output on sunny days at anchor with no motoring was 67 amp hours.

Our top-of-pole solar system addresses the need for power while at anchor and under sail.  In fact, we have found the solar system usually provides us an excess of electrical power while cruising.  Now we find the only additional thing we need while at anchor for an extended period is warm water for showers and cleaning dishes.  Sure there is the old black bag absorb the sun's heat option but this is a bit cumbersome.  
Then there is the option to run the engine until it heats up the water in the water heater.  Running the engine for warm water is inefficient and undesirable. 


Now we have what promises to be a pretty good solution; solar heated water.  Because the solar panel is dark in color, it absorbs a significant amount of the sun's energy in the form of heat.  This is dissipated through the back and front of the panel by air currents.  By attaching a heat collector/exchanger to the back of the panel, properly insulating it and circulating water through the heat exchanger we are able to collect that excess heat and store it in the water heater tank or in a separate holding tank.  While still in the test stages, we have completed proof of concept and can make the heat exchangers available to DIY mariners who are interested in setting up such a system.  We plan on offering a complete water heating system retro fit kit within the next year. 

Initial tests indicate that with our 140 and 160 watt systems we can heat 3 gallons of water from 60 to 110 degrees F in less that a half hour on a sunny day with the ambient temperature of 65 degrees F.

Our top-of-pole system is about to be a 3 in 1 assembly; solar panel mount, outboard motor crane and solar water heating system.  Call us if you are interested in participating in our test program.