Which solar array will recharge my batteries more efficienetly?

sparkey

I presently have 2, 110w polycrystalline solar panels wired in parallel  on my boat. Each of them are rated to output 6.3A at 17,3v. The most output I’ve seen on my battery monitor from them  is 12.3 amps.

I need to upgrade my solar to run my boat.  I am considering replacing them with 1, 365w REC, monocrystaline, black 120 cell panel that outputs 10.3A at 34.3v.  I am told that the new panel with the higher wattage and volts would put more amps in my battery than the 2 I have now even though it outputs less amps. Is that true?

BB.

12.3 amps from a 2 parallel panels x6.3a=12.6 amps is about ideal for a PWM type solar charge controller.

Could you get a little more current from an MPPT solar charge controller.

Maybe if you wired the two 17.3 Vmp panels on series and an MPPT controller on a cool & clear day...

They way right now it seems your system is performing as expected.

Yes, a larger array properly wired to a PWM or MPPT controller would supply more current (assuming your batteries will accept more charging current)...

For an optimum system, really need to know more.

Doing it wrong (I.e. a 36 Vmp panel driving a PWM controller on a 12 volt battery bank) the higher Vmp voltage will not help on PWM / 12 volt system.

Bill

sparkey

Thanks for your comment. I have a Moningstar TriStar 45 MPPT controller and 8 gauge wire.

sparkey

What do you mean when you say, “ MPPT controller would silly more current”? What do you mean by “silly”?

BB.

Auto correct on my phone... Supply more current...

Bill

sparkey

I realized that the REC panel I was interested in wont fit in my car for the drive to Mexico where my boat is. I have two other panels that I bought to put on top of my camper van that will fit in the car. I am wondering if they would add even more power than the 365w REC panel.
They are 2, 210w panels that put out 12.48A at 16.7v. Together they output 25A. I am wondering if these panels would give me more power than the 365w REC panel?

BB.

In theory, placing your existing panels in series for Vmp-array 34.6 volts would have the MPPT controller in it optimum MPPT voltage range.

Two panels in parallel Vmp-array 17.3 volts, the MPPT controller would be acting more like a PWM controller--Especially on warm to hot days where Vmp-array voltage falls (hot panels--Vmp and Voc falls from specifications).

For a 45 Amp MPPT controller, this controller would support:

• 45 amps * 14.5 Volts battery charging * 1/0.77 panel+controller deratings = 847 Watt array

Over paneling an MPPT controller is a cost effective method of getting the most energy from your solar array. You can use more panels (over paneling for poor average weather conditions and such) can be done too. MPPT controllers will safely and be design limit the output current to their rated amperage (and will reduce output if the controller starts to overheat).

The one thing with solar PV panels is that they lose 50% or more of their output if there is any shading (even just shading a single cell).

How is the array exposed to sun on your boat? Motor boat on roof with a clear view of the sun or a sail boat with lots of rigging and sails to block the sun? In conditions where some shading is envevable, and/or where you have "two planes" of arrays (one facing left, the other facing right), the panels on the same side should be wired in series sets. And the other side series wired in their own sets.

Solar panels when dark/shaded go "high resistance" and the bypass diodes go into conduction to route the current from the other panels around the dark panel.

-Bill