My New 7.56KW Ground Mount.. First Light, First Watts..

[Murby]

We got first light today on our new solar system install... only two columns (8 panels) are connected and its totally cloudy but we're producing almost 800 watts of power. When the clouds clear, the power jumps up to 1900 watts..
I still have five more columns (20 more panels) too hook up yet but we are producing.

Designed and built the system myself.. Using SMA SunnyBoy inverter and SolarWorld panels for a total DC rating of 7.56 KW and I have another 2000 watts of extra panels I haven't even hooked up yet.

Started laying out the positions of the support structure columns...

Placing concrete forms 6 feet below grade. Concrete forms are 22 inches diameter below grade and 20 inches above grade. I used steel 55 gallon drums with the tops and bottoms cut out and attached sonotubes to the top of them for the above ground sections.



Because our solar array is 40 feet long and located on an east-west slope, there is a 36 inch difference between the west side and east side so our concrete pillars had to extend above ground at varying heights to adjust for the changing grade.


Some of the Sonotubes are really tall!

After three weeks of almost no rain at all, which is really nice when you're digging holes, we got rain.. right at the time when I wanted rain the least.. All of our forms flooded and eventually were completely submerged and filled with water.. and then more rain.. and more rain..

I had to go to Harbor Freight and purchase one of their trash pumps.. Each concrete form held over 100 gallons of water..


When the weather finally gave us a break, it was back to work setting up wood supports to hold all the pipe that will make the solar framework.


More wood, more supports... The 3 inch sch40 pipe we used is very heavy.. All total, there's about 2800 lbs of framework. Just lifting a 10 foot piece is difficult to do manually... Heavy stuff...
Except the shortest pieces, all the vertical pipes had to be hoisted into position with machinery.


I have to say.. I'm tired of screwing wood together and working with steel pipe for a while...


I used 5000 psi concrete.. very strong stuff normally used for industrial applications.. Even so, I wasn't happy with the tallest sonotubes relying on their own structural integrity so I decided to embed rebar into the four tallest at the far side.. While it may look like the rebar is close to the concrete form, it is at least 3 inches away on all sides.


Finally time to pour concrete! Yippee!! 8 Cubic yards to fill up all the forms. And I was considering buying a concrete mixer and doing it myself.. Yikes! Glad I didn't go that route or I'd still be mixing concrete today.
The concrete driver was amazing! I was not able to allow him access to the low side of the array and we were really worried that he wouldn't be able to snake the concrete chute between all that wood support and piping.. but he did.. and he never touched or bumped a single part of the structure. Amazing skill..

To be continued.....

[Murby]

What a mess! Concrete everywhere.. Ruined my $25 Walmart shoes, my pants were covered in concrete, I even had concrete in my hair!


And then the nightmare continues with more digging for the electrical lines.. We had to run 150 feet back to the house panel so I used 4ga wire. I could have gotten away with something much smaller like 10ga or 8 ga, but smaller wire would have resulted in power losses.. The 4ga wire only suffers 0.8% at full power. We also laid in an auxiliary 1 inch conduit for other power wires and a 1/2 inch conduit for Ethernet communications to the array.


Finally able to remove the sonotubes and most of the support wood..



Do some grading and plant some grass seed and start installing rails and power systems.


Starting to look like a solar system...


A view of the inverter and back side of the panels...


Finally! All of the panels are up.. Anyone ever notice when you build something there's always extra parts left over? LOL
The extra panels are actually just back ups.. spares that will be stored in a Faraday cage for safe keeping.


I currently have just the first two columns closest to the camera hooked up.. I still have 20 more panels to wire but the first 8 are already producing power and feeding it back to the grid. Even on a cloudy day, I'm seeing between 400 and 1000 watts coming from them.. Very cool!

[bcroe]

Thanks for the pictures; very neat, super solid. I was wondering if you get snow?

Nice driving those wooden layout stakes. I have to use steel T posts cause the
wood has too much difficulty with all our rock (by the Rock River). Even then
sometimes they won't go down; have to move them over a bit. Bruce Roe

[J.P.M.]

FWIW, I suspect few could do as well. Looks fit for purpose.

[Murby]

Thanks for the pictures; very neat, super solid. I was wondering if you get snow?

Nice driving those wooden layout stakes. I have to use steel T posts cause the
wood has too much difficulty with all our rock (by the Rock River). Even then
sometimes they won't go down; have to move them over a bit. Bruce Roe

I'm in Michigan so we do get snow.. sometimes a lot of it.. It was a consideration during the design phase as someone in this forum was complaining that arrays which are too low in the front can be problematic when shoveling snow off them.
I didn't want anything to be within 36 inches of the ground.. Mostly for worry due to the lawn mower.. but the snow piling up was another huge consideration.

[AzRoute66]

Thanks for sharing the photos. Always nice to see the dirty details, especially when someone else is dealing with them.

[SunEagle]

That is an impressive ground built system. Looks very professional and my hat is off to all involved.

One question. How are you able to just energize only a part of the system and connect it to the grid?

I would have thought that the POCO would want the entire system wired and inspected before it got connected to the grid but each POCO and AHJ do things differently.

[bcroe]

I'm in Michigan so we do get snow.. sometimes a lot of it.. It was a consideration during the design phase as someone in this forum was complaining that arrays which are too low in the front can be problematic when shoveling snow off them.
I didn't want anything to be within 36 inches of the ground.. Mostly for worry due to the lawn mower.. but the snow piling up was another huge consideration.

In northern IL I have placed a gap between upper and lower panels (8" is good) for snow. It
means that only a fraction of the snow will accumulate in front. In addition you will only be
pushing half as much snow half as far to clear the panels, and increase the tendency of panels
to clear themselves. Cut my cleaning time to less than half. good luck, Bruce Roe

PV16D3.JPG

[idnominal]

I'm seriously considering not bothering with most snow clearing this year. Last year was my first winter following September turn-on, and I especially wanted to see production numbers through the winter (cleared after almost every snow, including one pretty funny half roof avalanche with 30" of snow). Now, it looks like I can make (May - August) as much power as I will need (Nov - Feb) in credits (with a bit of a surplus) going into this winter. Grid tied, March anniversary, no carry-over in NY.

28 LG 315s, Enphase S280s, similar in size to OP, much smaller than bcroe (WOW!). My pic is nearby community solar farm, my Chevy VOLT not my installation.

Almost forgot, Congrats to the OP, beautiful looking installation!

[Murby]

That is an impressive ground built system. Looks very professional and my hat is off to all involved.

One question. How are you able to just energize only a part of the system and connect it to the grid?

I would have thought that the POCO would want the entire system wired and inspected before it got connected to the grid but each POCO and AHJ do things differently.

I haven't actually be certified to do so yet.. I haven't run the DC lines for the other 5 columns.. just got the first two hooked up and... well.. you know.. I had to scratch that itch to see it work.

I have a smart meter on my home and it displays current usage and it was showing we were using between 700 and 1000 watts of power.. The computers were on, dish washer running, laundry running, and my kid was watching television on and off.. So I figured if I let the system generate 500 to 800 watts it wouldn't hurt anything or even really go into the grid since the house was sucking it all up.
Besides, I'd rather send an extra few hundred watts of free power into the grid rather than have to pay for it coming into the house...

Woke up with a bit of surprise this morning.. Do solar systems not get along well with GFCI breakers? I installed a GFCI breaker for the solar system to backfeed and found it tripped this morning.. A glitch? Or do I need to replace it with a normal breaker?

[sensij]

Woke up with a bit of surprise this morning.. Do solar systems not get along well with GFCI breakers? I installed a GFCI breaker for the solar system to backfeed and found it tripped this morning.. A glitch? Or do I need to replace it with a normal breaker?

Replace it with a normal breaker, your inverter has the necessary ground fault protection built in.

For a decent explanation of why you will get false trips, take a look at this:

http://solarprofessional.com/articles/design-installation/ungrounded-pv-power-systems-in-the-nec/page/0/6

[SunEagle]

I haven't actually be certified to do so yet.. I haven't run the DC lines for the other 5 columns.. just got the first two hooked up and... well.. you know.. I had to scratch that itch to see it work.

I have a smart meter on my home and it displays current usage and it was showing we were using between 700 and 1000 watts of power.. The computers were on, dish washer running, laundry running, and my kid was watching television on and off.. So I figured if I let the system generate 500 to 800 watts it wouldn't hurt anything or even really go into the grid since the house was sucking it all up.
Besides, I'd rather send an extra few hundred watts of free power into the grid rather than have to pay for it coming into the house...

Woke up with a bit of surprise this morning.. Do solar systems not get along well with GFCI breakers? I installed a GFCI breaker for the solar system to backfeed and found it tripped this morning.. A glitch? Or do I need to replace it with a normal breaker?

I agree with sensij. Replace the GFCI with a standard breaker.

As for having the itch to check out your system. I understand. Just be aware that some of the POCO meters do not subtract the power you generate and goes to the grid without first being programmed by the POCO . The issue is that some of the old meters will continue to charge you for each kWh it sees going in either direction because it doesn't know better to subtract what is sent to the grid.

Sure test your system but be aware you may actually be paying for what you send out until the Net Metering system has been approved and set up by the POCO.

[Murby]

I agree with sensij. Replace the GFCI with a standard breaker.

As for having the itch to check out your system. I understand. Just be aware that some of the POCO meters do not subtract the power you generate and goes to the grid without first being programmed by the POCO . The issue is that some of the old meters will continue to charge you for each kWh it sees going in either direction because it doesn't know better to subtract what is sent to the grid.

Sure test your system but be aware you may actually be paying for what you send out until the Net Metering system has been approved and set up by the POCO.

Looks like I'll be replacing the gfci breaker then.

I'm aware of the meter issue.. thanks!

[wienerdog]

Just wondering so the disconnect box mounted at the rack has the #4 going to it then did you run #6 to the inverter in the seal-tite as the inverter terminals only take #6? Did you run a #4 neutral also or did you downsize that?

I am putting in a similar system and I am up in the air on going AC to barn or mounting the inverter in the barn and taking DC to barn.

[Murby]

Just wondering so the disconnect box mounted at the rack has the #4 going to it then did you run #6 to the inverter in the seal-tite as the inverter terminals only take #6? Did you run a #4 neutral also or did you downsize that?

I am putting in a similar system and I am up in the air on going AC to barn or mounting the inverter in the barn and taking DC to barn.

The 4ga wire I purchased is a multi-conductor cord.. and industrial odd-ball you would never find in any normal hardware store. Its one cord and contains three 4ga copper conductors, plus four 12ga copper conductors, plus a 6ga bare ground wire. The cord is rated for outdoor use, direct sunlight, hazardous locations, and direct burial in hazardous locations. Its something like $12/ft and I bought 200 feet of it for $150 or something like that.

The small gray box mounted next to the inverter is an outdoor 125 amp 8-space circuit breaker panel... I ran the 4ga into that, then mounted a 30 amp breaker, and ran the 6ga from the breaker to the inverter through the flexible conduit.

In my case, one of the nice things about having the outdoor breaker box there is that I can install extra breakers later on.. I plan to install a 120 breaker and put some yard lights above the solar array to light up the back yard... I can then use the 12ga wires (not currently needed for anything) to run a switch into the house.

Along with the lighting, I also plan to put up an IP Camera and the network junction box will allow me to put an ethernet switch so a single Cat5 line can be used for both the inverter communications and the IP Camera. (But all that is down the road a bit)