first 24volt to 12 volt project

Hello and thanks for joining!

I'm going to move your question to the "off grid solar" forum so you can get more views and replies.

See you around.

230W of power @ 24V would be about 9.5A. 20' & 20' would be 40' round trip. So, if I was wanting to extract as much power as possible, I'd use a 12ga set of wires, on each panel, run back to the charge controller.
From what I've not forgotten about boats, is that what you want, is usually broken. So if you had tied both panels in parallel, and used 10 ga wire to connect to the controller, one wire would break, and you loose all charging. If you have each panel on it's own wire, you have twice as many wires to break (how's that for redundancy!) but better chances of one of them keeping the system going .

You do know that you should used tinned wires (each strand in the insulation bundle is tin/solder plated before the insulation goes on) to prevent the copper from corroding if you get any water or pinholes in the wire. (boat use = tinned wires, house use = plain copper wires.

From the boating forums:


Wire could hardly find a more hostile environment than aboard a boat. On-board wiring is salted and doused, shaken and whipped, crushed and abraded, exposed to sunlight, subjected to heat, and coated with petroleum. Neither lamp cord nor house wiring will long endure these conditions. Choose your wire carefully. Never use solid wire on a boat. Wave-or motor-induced oscillations eventually fracture solid wire. Boat wiring must have the flexibility stranding provides. Boatbuilders save a few dollars using type 2 wire, but a boatowner should use only the most flexible wire, called type 3. The wire must be copper, but even copper corrodes in the marine environment, and corrosion is the primary cause of electrical failures on a boat. Plating each strand of the wire with a thin coat of tin-called tinning--dramatically improves corrosion resistance. The additional cost of tinned wire is nominal, the benefits substantial. Under normal circumstances use only tinned wire.

solar on boats

thank-you mike.could you give me your opinion on the charge controller that i plan on using.

Worthless. I know folks who inherit them, and gut them to use the case or panel for something else. I feel the electronics are dated, and don't honestly downconvert with any gains.

I'd much rather steer you to the Rogue (60V max PV)


or the Blue Sky 2512 (35V max from the PV)

You may have answered a question for me already Mike.
I bought one of those controllers and I wasn't sure if it was working normally for an MPPT controller.
I have 10.2 amps shorted current out of my array but the best I ever get out of the controller to the batteries is 4.2 amps. It will show 12.8 volts and no charging amps for about 20 seconds, then there's a lot of relay clicking after which the voltage goes up to about 14 and the amps to about 4. Stays like this for about 5 seconds then goes back to 12.8 and no amps.
It seems to spend most of it's time not charging.
I have my array at 12 volt so I rewired it for 24 but it still does exactly the same. Put different batteries on as well in case it was them, no change.
Any ideas?

One of what ? controllers. BZ ? BS ? no name from china? Rogue ? Morningstar?

MPPT controllers don't have relays, it's all electronic.

It's a BZ MPPT250, and it clicks away like a demented deathwatch beetle.