Mighty Ground Mounts

[SunFarmer]

New member here. I’ve been lurking in the shadows for a few months soaking up knowledge. Been hoping to build a solar electric system for years (maybe even decades), the USA 30% tax credit is a good incentive to finally do it.

Background:
My wife and I live on property in the rural Maryland countryside west of Baltimore in the USA. Our lot is mostly wooded with only a small patch that gets enough sun for solar. Unfortunately, the sunny patch is close to a neighbor’s house, and this neighbor can be prickly. Therefore, I wanted to get a building permit just in case my neighbor complains about the project.

Originally, my plan was to construct a single wooden ground-mount structure to support a dozen panels each in the 450W range. But when I applied for the building permit, I learned about a county zoning requirement for a 30ft setback from my property line. This would have put the array in the shade of some big old trees, which I don’t want to remove. After several more attempts, I reached a compromise of constructing two smaller arrays for six panels each. With this arrangement I got approval to place them 10ft from my property line, where they will enjoy bountiful sunshine.

The next hurdle was the building review, where again my design was rejected. I came to learn that the county requires that “accessory structures” have to meet the same snow load strength as actual houses, even though there hasn’t been appreciable snow in these parts for 10 years. Originally, I planned to use 2x8 headers and 2x6 rafters. But to get it approved, I had to seriously beef up my design to use 2x10 headers and 2x8 rafters (and lots of them). The resulting ground-mount structures are overbuilt, but I played along and got the building permit.

Next up is digging a trench for running wires to the house.

 

[PunchySunshine]

New member here. I’ve been lurking in the shadows for a few months soaking up knowledge. Been hoping to build a solar electric system for years (maybe even decades), the USA 30% tax credit is a good incentive to finally do it.

Background:
My wife and I live on property in the rural Maryland countryside west of Baltimore in the USA. Our lot is mostly wooded with only a small patch that gets enough sun for solar. Unfortunately, the sunny patch is close to a neighbor’s house, and this neighbor can be prickly. Therefore, I wanted to get a building permit just in case my neighbor complains about the project.

Originally, my plan was to construct a single wooden ground-mount structure to support a dozen panels each in the 450W range. But when I applied for the building permit, I learned about a county zoning requirement for a 30ft setback from my property line. This would have put the array in the shade of some big old trees, which I don’t want to remove. After several more attempts, I reached a compromise of constructing two smaller arrays for six panels each. With this arrangement I got approval to place them 10ft from my property line, where they will enjoy bountiful sunshine.

The next hurdle was the building review, where again my design was rejected. I came to learn that the county requires that “accessory structures” have to meet the same snow load strength as actual houses, even though there hasn’t been appreciable snow in these parts for 10 years. Originally, I planned to use 2x8 headers and 2x6 rafters. But to get it approved, I had to seriously beef up my design to use 2x10 headers and 2x8 rafters (and lots of them). The resulting ground-mount structures are overbuilt, but I played along and got the building permit.

Next up is digging a trench for running wires to the house.

Nice start!

If I may suggest...rent a trencher! Your back will thank you and it'll be the right depth the whole way.

 

[SunFarmer]

Extra-Large Conduit!

I’m using 4” sewer pipe as conduit for running wires from the solar arrays to the house.

Background
Eight or nine years ago, I attempted to build a pico-hydroelectric system (even smaller than a micro-hydro). I constructed several test dams on a little creek to measure available water flow and head. I then found a bunch of 4” sewer pipe sections for cheap on craigslist, which was perfect for a penstock to move water from the dam to the location where I planned to build a small turbine.

Unfortunately, my dam backed the creek up into an already rusty culvert pipe which ran under the driveway. This caused the rusty culvert pipe to collapse, YIKES, and resulted in a $35K repair job. That was the end of my pico-hydroelectric dream. But I had all this 4” sewer pipe lying around, so I repurposed it as extra-large conduit. One this for sure, I’ll never run out of room for additional wires.

 

[niktak11]

You can fit around 289 10AWG THWN conductors in there without exceeding 40% conduit fill.

 

[StackedHusky]

I'm zoned agricultural so if the inspector asks questions, I'll just put a goat under it. Agricultural buildings don't require an inspection here.

 

[Brett V]

Very nice! Similar to what I did except your carpentry skills are light years better than mine.

 

[OffGridForGood]

I'm zoned agricultural so if the inspector asks questions, I'll just put a goat under it.

Do your Fences hold Water?
IF they do, then they MAY hold a Goat...been my experience...LOL
All kidding aside, Agr requirements are typically much more lenient than standard building codes, good to know if you have a homestead type of set up, and are not too worried about the structures.

 

[CTS]

Any chance you have some measurements for you ground mounts? I need to build a ground mount and I'm only looking at 6 panels total.

 

[Grateful Ed]

Sorry to hear about the governmental oversight, those babies are definitely built, what a waste of lumber. I'm in rural agricultural in VT and didn't even apply for a permit as my panels are far from borders and unseen by anyone but drones. I spent some time thinking and then drew my plans. They are at winter angle and I am betting they will get plenty of sun in the summer although I can retrofit them to make them adjustable if I really need. I was a little worried that they were not robust enough but they are rugged as hell. My panels are bifacial, I didn't know when I ordered them but I wanted to have as little shading as possible especially when there is snow on the ground, so I used cable as my bracing. It worked great. I will be posting a progress thread on my system, its close to done, I have been remiss, cheers!

 

[SunFarmer]

CTS: Attached is a PDF with my design plans for the mighty ground mount, although the rafters could be put on 24" centers. I had to use 19" in order to get building permit. I used GRK lag screws for all connections.

Also attached is picture of my southern array with panels installed. I used mid and end clamps from Beny's Solar and 2.5" lag screws to attach panels directly to wooded rafters.

Grateful Ed: Those are some amazing ground mounts. The panels are really going to soak up the sunlight.

 

[Zoomyn]

Such a handsome array.. . what neighbor could ever complain : )

PT wood is shipped wet - keeps fastener splitting down but shrinks as it dries - be vigilant to wood warp glass killer results as it dries PLUS panel clamps slotted at wood attachment points would be good to relieve movement tensions that can build up - that 11-foot rafter length can see some serious shrink as is bakes under the panels, 0.250" or 0.375" is easily possible and it varies from board to board...

Placing header/rafter lag bolts in at an angle will pay back that extra effort for years to keep end-grain weathering to allow attachment loosening : )

The last wood ground mount solar frame I got to help with we used metal 'pads' wrapped over wood edges to interface under panel brackets - stainless hdw, nyloc nuts and smooth washers, slotted brackets and milk jug plastic spacers to let the heave & shrink release as PV temperature changes and wood weathering kept it 'live'

 

[OffGridForGood]

that 11-foot rafter length can see some serious shrink as is bakes under the panels, 0.250" or 0.375" is easily possible and it varies from board to board.

Standard Spruce shrinkage longitudally is 0.1 to 0.2%
11 foot board length = 132" shrinkage .132 to .264 inches overall (over the full 11 feet of board)
typical PV panel is 7 feet long in it's longest direction = wood shrinkage in 7 feet length = 0.084 to 0.168" (about 1/8th inch)
Source Purdue Education service extension.

 

[SunFarmer]

Thank you good people. I'm going to back-out the panel mount screws a few turns to provide some wiggle room for expansion.

 

[handinpalm]

Extra-Large Conduit!

I’m using 4” sewer pipe as conduit for running wires from the solar arrays to the house.

Background
Eight or nine years ago, I attempted to build a pico-hydroelectric system (even smaller than a micro-hydro). I constructed several test dams on a little creek to measure available water flow and head. I then found a bunch of 4” sewer pipe sections for cheap on craigslist, which was perfect for a penstock to move water from the dam to the location where I planned to build a small turbine.

Unfortunately, my dam backed the creek up into an already rusty culvert pipe which ran under the driveway. This caused the rusty culvert pipe to collapse, YIKES, and resulted in a $35K repair job. That was the end of my pico-hydroelectric dream. But I had all this 4” sewer pipe lying around, so I repurposed it as extra-large conduit. One this for sure, I’ll never run out of room for additional wires.

Be careful on what type of wiring you use in buried conduit. Make sure it is rated for wet location, because buried conduit Will hold water from condensation over time. Use at least THWN / THHN-2 rated wire. Of course you need to look at the Max voltage rating too. Good luck on your project!

 

[SunFarmer]

Hello Forum,

Here is an update on my Mighty Ground-Mount Project.

Installed six solar panels on the second array, AND, passed the county’s building inspection. I’m now free of government oversight and will return to my normal operating practice, which is “Go Rogue”.

By the way, my panels are BlueSun 460W purchased from Signature Solar. Fortunately, I followed their recommendation and ordered two extra panels, because two panels were damaged in transit. This left me with a dozen panels so I could complete the project without waiting for replacements. I filed a damage claim with the Signature Solar and the carrier. Signature Solar made me several very fair options. I choose the store credit with 10% bonus.

Next up is to wire the panels and order an inverter and batteries.

 

[Zoomyn]

One little detail I’d be looking into, lightning & providing a better path for a direct strike a distant elsewhere - pick a tree and run a chunk of coarse stranded aluminum entrance cable up it, drive or bury a ground rod the give the far end a dandelion puff out of the strands with clear sight of the sky & that is cheap self-insurance against a major strike, the pre-strike leaders and field saturation will still be a separate issue…

And the drawback of complete wooden frame - perhaps put a ground rod & solid conductor up one of the posts to a point above everything else, I’ve sat next to hissing and glowing ‘leaders’ that are thousands of ‘em all competing to become the easiest path for the main strike - just being close will still prematurely age electronics & filters but not as bad as getting every panel & complete cabling all riding the unmitigated potential…

 

[SunFarmer]

Hmmm.... Sounds like "Lighting Rods".

I am planning to drive two 8ft copper-clad ground rods, one for each array and bond the panels to them. but now will also start thinking about lighting rods.

 

[Zoomyn]

Whatever gets done having a part of the system connected to two earth ground points with some distance between them is a problem as that becomes a circulation carrier for ground/air field surges that otherwise would be just slow changes…

 

[SunFarmer]

Hello Forum,

Reached another milestone with my off-grid solar electric installation. I finished wiring the arrays, which completes all outdoor work. (Just in time, frosty winter weather is expected next week for the east coast of USA.)

I installed an IMO disconnect for each of the two arrays and then a third IMO switch in the basement to disconnect the combined current. I repurposed two used AC disconnects and made them into PV junction boxes which hold 25amp fuses. I’m using the expensive ILSCO insulated multi-tap connectors as combiners and to transition from stranded PV wire to solid 10G UF-B cable with runs between the arrays and to the house.

Also, very exciting, received the EG4 6000EX-48HV inverter, three Lifepower4 batteries and battery cabinet from Signature Solar. All the equipment looks good, except the battery cabinet was bent a little lop-sided, which I straighten out using a ratcheting cargo strap.

Still on-track to commission the system before end of the year.

 

[Zoomyn]

Yow that must feel good

I had a buddy get inspector snubbed when his disconnect(s) did not break both (+) and (-) simultaneously... naturally he spent more money to make that go away : /

Is the green box off a ways behind the full array photo your utility powerco's distribution transformer?