Solar Wiring Diagram - Any Comments/Suggestions?

TechWriter wrote:

mena661 wrote:
You only need fuses on solar when you have a 3 or more string array.

You have a source for this?

http://www1.cooperbussmann.com/pdf/9df1f7ec-8c62-4210-8cf8-9504927394f0.pdf

"PV systems that have three or more strings connected in
parallel need to have each string protected (systems that
have less than three strings will not generate enough fault
current to damage the conductors/equipment and
therefore do not present a safety hazard as long as the
conductor was sized properly based on local code
requirements)."

"Once it has been determined that maximum short-circuit current
.... exceeds continuous current rating of conductor, follow the
recommendations of selecting the proper PV string fuse."

mena661 wrote:
You only need fuses on solar when you have a 3 or more string array.

You have a source for this?

You only need fuses on solar when you have a 3 or more string array.

Hi,

I do not see asking simple questions as harsh. I'm sorry my post was interpreted that way.

Load diversion is not needed--but with nearly 600 watts of solar a lot of the time the panels will have already charged the battery bank to bursting full. At that time, diversion load (which I think is on the pwm tristar already) could be used to power a 12 volt water heater. (added to the water heater in place of the drain plug).

KID controller has, er... kiddish size terminals :), and no remote monitoring. But this is beside the topic anyway, the OP's array mandates at least 40A controller.

alliemac9 wrote:
Hoping to continue to tap into the collective solar intelligence here...this is my wiring diagram for the system I am planning as discussed in this thread.

If you haven't purchased a controller, look at MidNite's new KID Controller. Also, there's a handy array sizing tool. Check out MidNite's Forums too.

I'm all for fusing, but I prefer resetable breakers. At the very least, they're a handy way of disconnecting each panel. Here's my PV schematic. I opted for all parallel PV connections.

You don't need the funny switch to choose solar vs or with converter.

-You can use both at the same time, no issues

-Should you want no solar, you already have the switch on the array side of the controller

-For solar only, no converter (why ever that?), You can use the battery disconnect switch to isolate the battery from the converter. I don't know if the battery disconnect switch is downstream from where you will parallel the controller and converter outputs. If it is, then you need another way to turn off the converter (by turning off its 120v eg)

- If you just plug things into the inverter or an extension cord from it, then no need to turn off the converter. If you plug the shore power cord into the inverter or into an extension cord from the inverter (like we do) then you need a way to turn off the converter's 120v.

alliemac9 wrote:
I'm not sure about battery voltage sense wires? Is this related to the TriMetric connections?

And I don't know what diversion load wiring is.

Voltage sense wire has nothing to do with Trimetric, but is a "recommended option" for Morningstar controllers. I think you need it.
Load diversion was, I believe, a tongue in cheek comment. Those are necessary with wind turbines, but in solar it's optional.

alliemac9 wrote:

This is what we preliminarily came up with - I mentioned that it seemed like others were putting fuses on each panel, but I never saw a discussion of why

Not on "each panel". There was a discussion, and the Handbook by Bussman-Cooper was quoted, which handbook said, on the page 5, that if Isc of parallel array exceeds the conductor/string rating calculated as 1.56*(PV Isc), string fusing is necessary: page 5.

In your drawing the left hand battery would contribute more power. Balanced wiring eliminates that. See the first diagram below for 2 12V batteries.

smkettner wrote:

alliemac9 wrote:
Interesting.... wondering if the combiner box will have enough room for three fuses? It hasn't arrived yet...

May need 4 fuses and 4 connections direct into the combiner.

I agree 4 fuses in the combiner box would be best.