solar installation

berwickberwick Registered Users Posts: 2
Hi, I am installing some more solar panels on our sailboat. Presently I have a Blue Sky2512 charge controller running 290 watts of solar panels (2-65w and 2-80w all in parallel). The 80w panels are prone to shading due to them being mounted on the bimini. I am going to add two 140w panels on the davits. I am looking for the best way (most efficient, esp with shading) way to hook up all these panels.
I think these are some of my options:
  1. Use two MPPT controllers (so they can work together), have one controller hooked up to the two 80w panels in parallel that are subject to shading, and the other controller, to two sets of series/parallel panel configuration. In other words one controller will take a nominal 12v panel input and the other a 24v panel input. My thought is that the MPPT is more efficient with the higher voltages so I would series the two sets of panels. I had read that paralleling is better if prone to shading thus the idea of doing this to the 80w panels. All the voltages in the panels are very close to the same but of course the current isn’t thus I would not string them all together.
  2. My other option is to parallel all 6 of them (larger wire) and run to one large controller. I guess if I am only using the nominal 12 voltages I could even go with a PWM controller instead of a MPPT as I am not gaining as much due to the nominal 12 volt system?
Am I gaining much more current/efficiency to the batteries by going the first route?
When you have two panels in series and you get a large shadow across one or both, do you loose mostly current from the cells and keep most of the voltage or do both decrease about the same? If it were mostly current then maybe two cells in series would work well with a MPPT controller which could still use the higher voltages?
Any better options I should look at?

Thank you

Richard

Comments

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,087 ✭✭✭✭✭
    Are you running refrigeration? The thing that is always a problem with solar is shade. Series connection just makes it worse. Sailboats do better with the panasonic/old sanyo solar panels. They have the best output per square foot but are 72 cell/24V panels.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • berwickberwick Registered Users Posts: 2
    Ok sounds good, is there much to be gained by using two charge controllers as the voltages of the panel are the same but not the current, so would this throw off MPPT if I use just one?

    Thanks

    Richard
Sign In or Register to comment.