mppt vs pwm

Those are copper coated aluminum, which means more voltage drop, so you must size up, accordingly.

I bought my 6ga welding cable from windy nation, on ebay, but do compare prices. I was allowing for 50' of portable though, with 16 amps coming from two 12v/140w in parallel.

Do you realize that is copper clad aluminum wire?
Doubt the insulation is UV rated.

I suggest you get some real MC4 cable designed for solar. Available up to #8 wire. I believe those panels have MC4 connectors so you may also want some parallel MC4 connectors and make it all plug and play.

Yea it will cost a bit more to do it right.

The balance would have to be pretty good IMO or all the amps would go down the path with the least R or at least the amps would be in proportion to the different R amounts. You could smoke one of the controllers if each is near maxed with the hoped for split and you don't get as much split as you hoped for.

Doesn't matter with $20 eBay PWM controllers, but it would hurt to fry one if they were hundred$ each!

I did run two 20a controllers from one panel feed through a Y in hopes of each controller taking half the amps of the array. I was not able to measure how many amps each controller was getting (needs a clamp on ammeter)

I did confirm getting the total array amps to the battery bank ok, just no idea how many amps from each controller.

That's definitely in my pricing equation. The biggest benefits I have is the amount of space I have available for my setup and no hard time frame to have this completed (although it would be nice to have it together for a Colorado road trip in July).

Here's a quick and dirty source for 12' of 2-conductor 8 gauge wire:

http://www.harborfreight.com/12-ft-8-gauge-heavy-duty-booster-cables-69295.html

16' of 2-conductor 6 gauge wire:

http://www.harborfreight.com/16-ft-6-gauge-heavy-duty-booster-cables-60396.html

12' of 2-conductor 10 gauge wire:

http://www.harborfreight.com/12-ft-10-gauge-heavy-duty-booster-cables-69294.html

Keep in mind, as you add more and more controllers, you also need more wiring AND more circuit breakers between controllers and batts. And 23 amps input would require heavier wiring from panels to controllers.

Perhaps the best solution would be to go with TWO higher voltage controllers, and wire the panels in series/parallel. But to keep costs down, you may have to give up adjustable voltage set points. And mc4 'Y's don't come free.

CA Traveler wrote:

Bedlam wrote:
If all four panels were in connected in parallel, it would give me 544w @ 24VDC (just under 23A). Running this one feed to the inputs of three 20A controllers should balance out between the controllers. Am I missing something in this type of setup?

My understanding is that parallel controllers are connected on the controller outputs only to the battery and not on the panel inputs.

So is it not possible to use multiple smaller controllers off one large power feed as long as the voltage is within the controller range and the sum of the controller capacity is greater than the feed? I'm asking these questions prior to making a purchase and not trying to get something to work that I already have on hand. I assumed that running parallel controller inputs would be like running parallel loads off one source.

Bedlam wrote:
If all four panels were in connected in parallel, it would give me 544w @ 24VDC (just under 23A). Running this one feed to the inputs of three 20A controllers should balance out between the controllers. Am I missing something in this type of setup?

The wiring itself would be easy enough;

4 panel pos and 4 panel neg to a pair of 4-into-1 'Y's... Two wires to a pair of 3-into-1 'Y's, near controllers... 1 pos and 1 neg to each controller.

Not really sure how well it would balance out?

I do like the redundancy, though.

.

Bedlam wrote:
If all four panels were in connected in parallel, it would give me 544w @ 24VDC (just under 23A). Running this one feed to the inputs of three 20A controllers should balance out between the controllers. Am I missing something in this type of setup?

My understanding is that parallel controllers are connected on the controller outputs only to the battery and not on the panel inputs.