Ground Mount w/ SolarEdge 10kw Grid Tie Inverter

[jorgey]

Looking at installing a SolarEge 10kw grid tie system. The array itself will be about 250 to 300 feet away from the house (and the electrical hookup).

Would it be better to install the inverter at the array and run AC the 300 feet to the house, or run DC the 300 feet and mount the inverter at the house (outside or in attached garage)? The array would consist of 40 - 260 watt panels, split into 2 strings. From what I have read here and other places, I "should" be able to do either, but would like the recommendation as to what would be best to minimize any loss over the run.

I think that I should be able to run either AC or DC with 6 gauge wire that distance and not have much loss. (DC probably a little better.) Not sure if that is right or not, please correct me if I an wrong. I would like to know if I have the gauge of wire correct and what the recommended mounting location of the inverter would be, ideal situation (array or house, inside or outside).

Thanks.

[inetdog]

Very simple rule of thumb for starting: Make the longer run at the higher voltage.

By that guideline, it would be more efficient (only in terms of wire cost) to run DC at 300V the longer distance instead of AC at 240V. (or worse at 120V).
But maintenance, environment, security and other issues are probably more important than the difference between 300V and 240V.

PS: For DC you will be running two or three wires for one string. For AC you will be running 3 wires plus a grounding conductor (EGC).

[jorgey]

Very simple rule of thumb for starting: Make the longer run at the higher voltage.

By that guideline, it would be more efficient (only in terms of wire cost) to run DC at 300V the longer distance instead of AC at 240V. (or worse at 120V).
But maintenance, environment, security and other issues are probably more important than the difference between 300V and 240V.

PS: For DC you will be running two or three wires for one string. For AC you will be running 3 wires plus a grounding conductor (EGC).

Thanks inetdog!

Sounds like DC is definitely the way to go. Is 6 gauge wire going to be sufficient to handle that long of run?

I would be using one of the SolarEdge DC optimizers on each panel and I believe that the wire from them is 10 gauge. What do you recommend at the array to tie the strings into a the larger gauge wire to make the long run?

[inetdog]

Thanks inetdog!

Sounds like DC is definitely the way to go. Is 6 gauge wire going to be sufficient to handle that long of run?

I would be using one of the SolarEdge DC optimizers on each panel and I believe that the wire from them is 10 gauge. What do you recommend at the array to tie the strings into a the larger gauge wire to make the long run?

You can use an online voltage drop calculator like the one at http://www.southwire.com/support/vol...calculator.htm.

Using 6AWG wire and a current of 12A, the voltage drop over 300 feet will be slightly over 1%, which is a very good number.
Depending on the actual output current of the array (roughly array power divided by 300V), you could possibly get away with just continuing the 10AWG.
That number, using 10000watts, is 33.3 amps. For that, I would indeed go to 6AWG. That would give you 3% voltage drop.

Depending on the temperature conditions at the array and how the wires are run, that is potentially more than 10AWG is rated for in the first place.

As far as connecting goes, a junction box is required for any such transition. Inside the box you can use wire nuts, terminal strips or even crimped butt connectors designed for the two wire sizes. It can be useful to have a point to disconnect and make measurements, so the terminal strip is attractive. Or you can make the transition at the location of the series fuse (mandatory).

[sensij]

SolarEdge nominal DC voltage is 350 V, with a tendency to run a bit higher (up to maybe 380 V).

Also, keep in mind that max string size is 5250 W, so you are looking at two, maybe three strings with that inverter. You can decide whether to combine at the array and user fewer heavier conductors or combine near the inverter and use more lighter conductors.

[Ben25]

You can combine the 2 strings unfused at the array and run one string back to the inverter. 6awg would probably be fine but I haven't done the calculations on it.

[jorgey]

The inverter that I am looking at is the SolarEdge SE10000A-US-U. I may be looking at the info about this unit wrong, but I am under the impression that this unit only has the ability of connecting 2 strings at 5200 watts max each. That would mean that I could have 2 strings of 20 - 260 watt panels. Is that correct, or am I missing something here?

[ButchDeal]

The inverter that I am looking at is the SolarEdge SE10000A-US-U. I may be looking at the info about this unit wrong, but I am under the impression that this unit only has the ability of connecting 2 strings at 5200 watts max each. That would mean that I could have 2 strings of 20 - 260 watt panels. Is that correct, or am I missing something here?

The inverter has two connectors on it for strings with a max string wattage of 5250. You can combine them on the roof or at the inverter. With just two strings that is your best option, though you could do combinations of 3 strings to connect more modules to the SE10000 inverter.

[jorgey]

The inverter has two connectors on it for strings with a max string wattage of 5250. You can combine them on the roof or at the inverter. With just two strings that is your best option, though you could do combinations of 3 strings to connect more modules to the SE10000 inverter.

Great, thanks for the info.

[Cosmacelf]

FWIW, the data sheet on that inverter specs the maximum gauge wire to be 6 gauge.

Also, how are you connecting the inverter to the Internet? if Ethernet, be aware that the maximum length for a regular twisted pair Ethernet cable is 330 feet.

[jorgey]

FWIW, the data sheet on that inverter specs the maximum gauge wire to be 6 gauge.

Also, how are you connecting the inverter to the Internet? if Ethernet, be aware that the maximum length for a regular twisted pair Ethernet cable is 330 feet.

Thanks for the info. I've been thinking that I will run DC from the array and mount the inverter at the house so my ethernet cable will only be about 20 feet long at the most.

[bcroe]

Also, how are you connecting the inverter to the Internet? if Ethernet, be aware that the maximum length
for a regular twisted pair Ethernet cable is 330 feet.

Sure for a single cable. But putting a $10 "ethernet switch" as a booster every 250' or so will let it be
extended indefinitely, if that is practical. Doing that here. Bruce Roe

[foo1bar]

Sure for a single cable. But putting a $10 "ethernet switch" as a booster every 250' or so will let it be
extended indefinitely, if that is practical. Doing that here. Bruce Roe

To do that, you need power at that location as well. Ovious choices would be an outlet or powered via power-over-ethernet.
And of course a place that the little switch can live and not get wet (nor too hot). (

[bcroe]

To do that, you need power at that location as well. Obvious choices would be
an outlet or powered via power-over-ethernet.
And of course a place that the little switch can live and not get wet (nor too hot). (

Those pretty well define my "practical". Fortunately my buildings are all less than 300' apart.
No pedestals sticking out of the yard (yet). Bruce Roe

[radareclipse]

This thread was one I had a similar question on, running from a distance to the house a ground mount setup. However I am going to do 3 or 4 pole mounts. Each pole would have 12 panels as a one string. So I'm either going with 3 poles (36 panels) to one inverter, or 4 poles (48 panels) to 2 inverters (SolarEdge).

The house is in the country, so less rules and reg's, but do I need a DC disconnect of some sort on each pole?

In the case where I might do 4 poles/strings and 2 inverters, could I get away with doing a Midnight Solar Combo Disc box like this one where I could run the four strings into it and then two strings out to my two inverters and not have to do some type of DC disconnect on each pole?

http://www.altestore.com/store/Enclosures-Electrical-Safety/Electrical-Enclosures/Disconnecting-Combiner-Boxes/Midnite-Solar-MNPV8HV-3R-DisconnectCombiner-Box/p10340/

If I need a disconnect on each pole, can you recommend something plain and simple? Every panel on the string is in series, so close to 500v. Weather goes from below zero worse case (-15 wind chill) to a little above 100 if that matters.