SOLAR OUTPUT ON SAILBOAT

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!

Comments

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    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.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    edited January 2016 #3
    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...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • tidetimtidetim Registered Users Posts: 10 ✭✭
    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!!
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    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...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    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.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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