SMA Secure Power

[Murby]

I'm installing an SMA Sunnyboy 6.0 with secure power supply. The inverter is mounted to the panel racking which is about 70 feet from the house.
My question:
Can I run a separate direct burial line from the inverter back to the house for the secure power? or does it have to be mounted right at the panel? I wanted to bury an extra 10ga line with the main 4ga power feed so the plug for the secure power would be inside the home even though the inverter is outside.

Any problems with doing this? I think I saw there needs to be a switch installed for the secure power circuit but I don't care if that switch is next to the inverter or inside the home.. as long as I can get the plug inside the house.

[max2k]

I'm installing an SMA Sunnyboy 6.0 with secure power supply. The inverter is mounted to the panel racking which is about 70 feet from the house.
My question:
Can I run a separate direct burial line from the inverter back to the house for the secure power? or does it have to be mounted right at the panel? I wanted to bury an extra 10ga line with the main 4ga power feed so the plug for the secure power would be inside the home even though the inverter is outside.

Any problems with doing this? I think I saw there needs to be a switch installed for the secure power circuit but I don't care if that switch is next to the inverter or inside the home.. as long as I can get the plug inside the house.

I'd be more concerned about grounding issues in this setup and make sure I have both array and the house at the same potential in case of lightning strikes regardless of SPS use.

[SunEagle]

If you have to go out to the inverter to "switch on" the secure power source why don't you just plug an extension code in at that time.

Why go through the trouble of digging a trench and installing the wire under ground where it can deteriorate from moisture and as max2k points out a potential lighting strike finding a path into the house?

[Murby]

I'd be more concerned about grounding issues in this setup and make sure I have both array and the house at the same potential in case of lightning strikes regardless of SPS use.

My system is a "ground mount" system. I can sink an extra ground rod into the soil next to the SMA inverter and tie together the ground rod, the inverter, and the house's ground system inside the breaker box.. It would effectively become one big ground system with a grounding rods at both the array and the house all connected together.

Does that sound adequate ?

[Murby]

If you have to go out to the inverter to "switch on" the secure power source why don't you just plug an extension code in at that time.

Why go through the trouble of digging a trench and installing the wire under ground where it can deteriorate from moisture and as max2k points out a potential lighting strike finding a path into the house?

Because then I'd have an extension cord running across the back yard.. I'd have to hook it up each time, and I'd have larger voltage drops.

I have to dig a ditch anyhow to run the main power line from the array to the home's breaker box.. how many wires I put in the ditch makes little difference at that point. In fact, as it stands now, I'm going to be burying a 4ga (direct burial) cable, then a few inches of dirt, then a 1/2 inch pvc conduit for the ethernet (cat6 line).. Seems like the perfect opportunity to install a 10ga direct burial line for the Secure Power outlet, just have to make sure there's a few inches of dirt between the network cable and the power cables.

My system will be sending about 25 amps (240volts) back to the house over 100 feet of wire. I could have gotten away with 6ga wire but I found some 4ga copper for scrap price.. Only paid $100 for a 175ft piece of direct burial cable..

All advice and comments are much appreciated.

Thank you!

[inetdog]

If you have to go out to the inverter to "switch on" the secure power source why don't you just plug an extension code in at that time.

Why go through the trouble of digging a trench and installing the wire under ground where it can deteriorate from moisture and as max2k points out a potential lighting strike finding a path into the house?

It is certainly possible to run the switch circuit remote from the inverter along with the SPS output circuit.
There is no switch for that purpose on the inverter. It must be installed as part of the SPS wiring whether it ends up being close to the inverter or far from it.

[max2k]

It is certainly possible to run the switch circuit remote from the inverter along with the SPS output circuit.
There is no switch for that purpose on the inverter. It must be installed as part of the SPS wiring whether it ends up being close to the inverter or far from it.

I'd be concerned with remote installation of the switch from electromagnetic point of view- laying next to the power wires it would get some voltage generated in the switch control wires. Depending if the switch wires control some low voltage input circuit or directly SPS wires this could be a problem or not. I don't see that info in the manual. May be contact SMA ppl and share their response here?

[Murby]

I'd be concerned with remote installation of the switch from electromagnetic point of view- laying next to the power wires it would get some voltage generated in the switch control wires. Depending if the switch wires control some low voltage input circuit or directly SPS wires this could be a problem or not. I don't see that info in the manual. May be contact SMA ppl and share their response here?

I don't plan on running the switch circuit.. just the power circuit and even that will be separated by six inches of dirt.

My ethernet cable will be separated by another six inches of dirt too.. all buried 48 inches down.

[SunEagle]

Because then I'd have an extension cord running across the back yard.. I'd have to hook it up each time, and I'd have larger voltage drops.

I have to dig a ditch anyhow to run the main power line from the array to the home's breaker box.. how many wires I put in the ditch makes little difference at that point. In fact, as it stands now, I'm going to be burying a 4ga (direct burial) cable, then a few inches of dirt, then a 1/2 inch pvc conduit for the ethernet (cat6 line).. Seems like the perfect opportunity to install a 10ga direct burial line for the Secure Power outlet, just have to make sure there's a few inches of dirt between the network cable and the power cables.

My system will be sending about 25 amps (240volts) back to the house over 100 feet of wire. I could have gotten away with 6ga wire but I found some 4ga copper for scrap price.. Only paid $100 for a 175ft piece of direct burial cable..

All advice and comments are much appreciated.

Thank you!

I believe I understand your reasoning.

In my case I wouldn't want to spend the extra cash to bury the wire for the secure circuit. Chances are very high that if I loose power it will not be sunny so the secure circuit would be useless to me. For the few times I could lose power during the day, it would be easy for me to run that long extension cord if I needed it.

Like I said it comes down to what each person feels they need to do to have an "emergency power" source. I rather spend the money on a nice inverter style generator. That would work day or night and still get me 2000 watts of power for hours.

[max2k]

I don't plan on running the switch circuit.. just the power circuit and even that will be separated by six inches of dirt.

My ethernet cable will be separated by another six inches of dirt too.. all buried 48 inches down.

Ethernet are twisted pairs which would efficiently eliminate any alternating magnetic field induced currents, besides it's much higher frequency so that should work just fine. The distance is a little excessive for Ethernet but good CAT6 should be able to get you through at 1Gb/s min.

IMO running SPS back to the house is fine as long as you take care of the grounding- bonding grounding rods of 2 sites together with at least #6 ga unspliced copper wire. Just don't make 2 isolated grounds or 2 grounds which are connected by thin wire which is essentially the same as it would simply evaporate in case of lightning strike. That wire needs to carry insane currents for the short time. If it is not there lightning currents will find their way to the ground through remaining wires/equipment/people/dogs/... Your ground rod at the array or even system of the ground rods there won't be able to ground the entire charge as the soil itself 'jumps' during the strike. The point is to make both sites 'jump' together.

I'm curious if you could utilize Ufer ground system at your array location- this depends how your concrete posts are done: http://www.ecmag.com/section/codes-s...at-ufer-ground. Please note if you go this way you'd need to bond posts together to create Ground Electrode System and still run the same wire back to the house grounding rod. Ufer ground replaces ground rod at the array but array ground still needs to remain bonded to the house ground rod.

[Murby]

My array is on a slope.. The 40 foot distance of the array changes elevation by 30 inches with the lowest elevation being just a few feet above the water level of the pond. I plan on sinking the array grounding rod at the lowest elevation where it will remain wet at all times except maybe the occasional super dry summer that happens once every decade or so.

The inverter is located at the array and is about 140 feet from my home's breaker panel.. I am using 4 gauge copper wire w/ground and all will be bonded together...