SOLAR OUTPUT ON SAILBOAT

tidetim · January 2016

Three years ago I installed 3 135 watt solar panels (flat, little/no obstructions) mated to a MPPT (Blue Sky) controller to help maintain my boat's battery bank (2 4D AGM's, approx 400 amp/hrs - 1.5 years old). The panels run separately to a below-deck bus bar via MC4 cables, then parallel to the controller (8 gauge wire) and then battery bank. While in the Bahamas I saw over 25-27 amps during peak sunlight hours. We are now in Florida (Stuart) waiting to cross to the Bahamas and even during peak production hours, only getting 16-18 amps. I've checked all the panels and they are equal in production (3-4+ amps), that number triples (3 panels) going into the controller and then gets that MPPT "boost" going to the battery bank. I keep the panels clean and all connections are corrosion free. Other than all three panels failing at the same time, I am baffled as to why the loss of close to 10 amps. I had a marine electrician (not necessarily a solar expert) check my system and he could find no problems. Any help from here would be much appreciated!

Dave Angelini · January 2016

Probably the angle of your panels and less than a month from the winter solstice. Too bad you can't log the peak power and compare days and months, you probably would see that all is well.

westbranch · January 2016

Which Blue Sky MPPT CC do you have? If it is the 2000e you may be pushing its upper limits with those 3 panels. Theoretically I was exceeding its limit with more than 2 120W panels....3 went over...

tidetim · January 2016

Thanks for responses thus far. We are in S Florida (approx 27 degrees N) and sun, while not directly overhead, is not far off. I have the Blue Sky 3024 MPPT controller which, I suspect you know is more than enough for my 400 watts of panels.
Keep suggestions coming!!

westbranch · January 2016

Really all that is left is to add more panels to cover off the winter period losses in input &./or tilt the panels to get better interception.. I assume you are moored at a dock so there is not the issue of swinging on the anchor line...

Dave Angelini · January 2016

Get a tracker ? Sorry just kidding. The amps you measured long ago really need a voltage to be meaningful.
Small systems like this can output more amps at lower voltage but can be harder to get amps out at bulk absorb. Just a guess.
You can test the short circuit current of each module and check if they have degraded.

SOLAR OUTPUT ON SAILBOAT

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