USE or UF cable transition to romex for solar panel array

[Zee]

NM for solar?

Absolutely, for AC output.

[Sunking]

What insane R factor are the exterior walls ?

Not as high as one might be inclined to think. The real advantage of ICF is not high R values which you do get, but it is the extremely high thermal mass, very few thermal bridges, and almost ZERO air and vapor migration. But to answer your question around R 35.

[Zee]

whether I can use romex (12-2 or 10-2 with ground) in the basement co carry the current from the inverter to the ac disconnect and then panel. And, the location of the AC disconnect as to where it must be located. I know it must be located outside per utility company regulation, I am just not sure it it needs to be located outside the house near the inverter or outside the house on the other side where the electrical service panel and meter are.

You will also have to run a min. #8 DC GEC (Ground) from the inverter to the meter/main or (E) ground rod.

12 gauge wire more than enough for 700U. Rx fine. (You can run flex conduit.........and pull in ac wires and DC ground also.)

AC disco:
2 main requirements:
CODE - one AC Disco must be in line of sight from inverter. (next to it basically)
Utility - one AC Disco must be at Meter/main. (some utyilities are fine with PV breaker in meter/main counting as AC Disco. Check with them.)
Sounds like you need both.

[Zee]

WAIT.
How many 250W panels will you have on a 700W inverter? "4-6"?

[inetdog]

WAIT.
How many 250W panels will you have on a 700W inverter? "4-6"?

Six 250 watt panels with a 700w inverter is not at all unreasonable if the light is not good, the panels are pointed in different directions, or the OP just wants to get max output from the SunnyBoy over a much greater number of hours, especially in winter.
Probably not economical to set out to buy that many panels without having solid plans to expand, but Dereck tells us that panel prices will be going up, and they will "store" just fine out in the sun until fully needed.

[Zee]

Six 250 watt panels with a 700w inverter is not at all unreasonable if the light is not good, the panels are pointed in different directions, or the OP just wants to get max output from the SunnyBoy over a much greater number of hours, especially in winter.
Probably not economical to set out to buy that many panels without having solid plans to expand, but Dereck tells us that panel prices will be going up, and they will "store" just fine out in the sun until fully needed.

Yes, i agree, it is not necessarily a bad idea.
I just am curious why he wants 1500 W on a 700 W inv.
Also, I am not sure the OP has considered what you wrote about.

Also, he mentioned ground rack, which i am 99% sure will face all panels a single direction.

Maybe he's in Alaska

I suspect 3 panels won't hit the min DC V threshold of the 700U.

[sirsparky]

Article 690

Article 690 specifically states that DC conductors within a building must be in metal conduit. Your basement is considered within a building and you must run the DC conductors inside in metal conduit. You'll be called out by an inspector if you don't and it's also hazardous to you or anyone who ever does any work inside your house that might accidently cut into an unprotected DC conductor. The metal conduit is also required by NEC to be labeled so that everyone is aware that it is a "DC solar circuit".

[Naptown]

Article 690 specifically states that DC conductors within a building must be in metal conduit. Your basement is considered within a building and you must run the DC conductors inside in metal conduit. You'll be called out by an inspector if you don't and it's also hazardous to you or anyone who ever does any work inside your house that might accidently cut into an unprotected DC conductor. The metal conduit is also required by NEC to be labeled so that everyone is aware that it is a "DC solar circuit".

that was covered in post #2

[sirsparky]

My bad, I missed that earlier post. Don't put Romex inside conduit as along with the GEC it won't be any easy wire pull. Go buy some THHN at home depot.

Someone discussed the Inverter strike aka startup voltage earlier. I agree that you might need 4 panels just to start the darn inverter. Anything more than 4 panels is a complete waste of solar panels. Those older Sunnyboys aren't very efficient but putting 1000 watts of solar into a 700 watt inverter is probably about maxing this Old Inverter out (unless you're living in the middle of the Mohave desert).

Another concern is that the Sunnyboy 700 has a max Input current rating of 7 amps and those new 250 watt panels have an Imp (operating current rating) of at least 8 amps. I would highly advise contacting SMA tech support before tieing 250's to this particular Model of Inverter.

Here's a data sheet:

http://www.solarpro.com.mx/v1/files/sunnyboy700.pdf

[sirsparky]

Overvoltage

Forgot to mention in my earlier post that the Model 700U Inverter has a very low DC maximum voltage rating. Be very careful how many panels you wire in series and input to this Inverter. If you use 6 newer panels you will likely overvoltage damage this Inverter. Check with SMA to determine how many panels you can series string connect into this Inverter.

Again here's a data sheet - http://www.hardysolar.com/grid-tie/d...boy-700-us.pdf

[inetdog]

Article 690 specifically states that DC conductors within a building must be in metal conduit. Your basement is considered within a building and you must run the DC conductors inside in metal conduit. You'll be called out by an inspector if you don't and it's also hazardous to you or anyone who ever does any work inside your house that might accidently cut into an unprotected DC conductor. The metal conduit is also required by NEC to be labeled so that everyone is aware that it is a "DC solar circuit".

One of the risks of high voltage DC wiring where exposed, unlabeled, to either the DIYer or the professional electrician is that smooth DC will not trigger a non-contact voltage detector. That could lead someone to believe that the conductors have been safely de-energized even though they have up to 600 volts on them.