New Off Grid Solution Feedback

Hi everyone, I'm doing my first off grid install for my own home. I would like to get some feedback on what I have so far from anyone generous enough to provide it.

This is not going to be connected to grid power and will support an RV and some minimal requirements while we build an off grid home. I'm using Sketchup Web to diagram the system, my apologies, I can't seem to get the line colors to change which is why they are all black instead of red, black, grey and green. I've already bought the panels, inverter, and batteries from Current Connected and Signature Solar, so feedback on using different components won't be super helpful. I haven't purchased any of the electrical hardware and components yet.

Some questions I would love more feedback on to make sure I have the concepts right:
- Is my main breaker seem reasonable on the electrical panel? I see 60A used a lot with 18k in other designs, is that due to the max output of the inverter?
- I think I have sizing right on my solar arrays for each MPPT for the EG4 18k based on what I've learned from the manual all the folks here in reading through other posts, but please sanity check me
- Does it make more sense to add a generator to the 18k or via Chargeverter setup, I can use one or both of my Predator 5000 generators with a pairing kit. They are inverter generators so provide clean power. The guys at Current Connected said forego the Chargeverter, but I see a lot of feedback on needing enough power from the generators to run all loads + charge the batteries, which might push the Predator generators past their limit?
- Should I be incorporating Surge Protection Devices (SPD), like from Midnight Solar?
- I'm assuming I should add a PV Disconnect as well between the arrays and inverter?

Link to Generator: https://www.harborfreight.com/5000-...ote-start-and-co-secure-technology-70143.html
Link to Parallel Kit: https://www.harborfreight.com/rv-ready-50-amp-inverter-generator-parallel-kit-58374.html

For context, eventually when the home is built, I will be adding another EG4 18k, three more wall mount batteries, with 36 more of the Hyperion panels. All inverters and batteries will be installed in a shipping container. Appreciate any feedback!

Officient said:

- Is my main breaker seem reasonable on the electrical panel? I see 60A used a lot with 18k in other designs, is that due to the max output of the inverter?

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Breakers protect the wires. Size the breaker for the Wire. I believe the 18kpv can output 12kw continuous, which is 50 amps. 125% of that is 62.5 amps, hence the 60 amp breaker. Consider upsizing now since you plan on paralleling at least one more 18kpv.

In off grid, each 18kpv can have its own connection to the load (each comes into a different breaker on the load panel). That works too. Helps if you want to take one out of service.

Officient said:

- I think I have sizing right on my solar arrays for each MPPT for the EG4 18k based on what I've learned from the manual all the folks here in reading through other posts, but please sanity check me

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Max voltage on MPPT is 600v. You are showing 450v. Don't know if that is Voc. If not Voc, then you need to check.

Officient said:

- Does it make more sense to add a generator to the 18k or via Chargeverter setup, I can use one or both of my Predator 5000 generators with a pairing kit. They are inverter generators so provide clean power. The guys at Current Connected said forego the Chargeverter, but I see a lot of feedback on needing enough power from the generators to run all loads + charge the batteries, which might push the Predator generators past their limit?

Click to expand...

If you have inverter generator that can be in parallel with each other, then you don't need the Chargeverter to clean up the power. There is something about the 18kpv not working great with Generators. But, there is a "Gen Rated Power" setting that should keep the 18kpv from overloading the generators.

Note: You are supposed to parallel the gen input. If you have the CV charging the battery directly, then you don't have to parallel that connection.

Officient said:

- Should I be incorporating Surge Protection Devices (SPD), like from Midnight Solar?

Click to expand...

Can't hurt.

Officient said:

- I'm assuming I should add a PV Disconnect as well between the arrays and inverter?

Click to expand...

Some way to stop power in the string is helpful. Let's say you want to move a string from one MPPT to another. Disconnect (or RSD) lets you do that during the day.

Thank you for the feedback, very much appreciated.

DIYrich said:

Breakers protect the wires. Size the breaker for the Wire. I believe the 18kpv can output 12kw continuous, which is 50 amps. 125% of that is 62.5 amps, hence the 60 amp breaker. Consider upsizing now since you plan on paralleling at least one more 18kpv.

In off grid, each 18kpv can have its own connection to the load (each comes into a different breaker on the load panel). That works too. Helps if you want to take one out of service.

Click to expand...

I like the idea of future proofing. So, to size for 2 EG4 18k units, I would go with an 125 AMP breaker minimum with #1/0 cable. To size for a 3rd 18k unit down the road, I could go with a full 200AMP panel with #3/0 wire. Sounds like I would combine the circuits in small panel prior to the main loads panel and feed into the main panel on the main 125AMP or 200AMP breaker. Or, as you suggested, just add 60AMP breakers on the main load panel for each inverter. Any trade-offs to consider between having the inverter combined in a separate panel prior to the main panel other than saving more breaker space for other uses in the main panel?

DIYrich said:

Max voltage on MPPT is 600v. You are showing 450v. Don't know if that is Voc. If not Voc, then you need to check.

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Yes, 36.98v is the VOC, see here for the 395 watt Hyperion panel: https://signaturesolar.com/product_images/HY-DH108P8 390-410W-202110 (short cable) (2) (2).pdf

Are you thinking I should do 14 per string perhaps? I have a total of 72 panels already purchased, so my thought was 6 strings of 12 panels total, 3 per 18k when it's all said and done.

DIYrich said:

If you have inverter generator that can be in parallel with each other, then you don't need the Chargeverter to clean up the power. There is something about the 18kpv not working great with Generators. But, there is a "Gen Rated Power" setting that should keep the 18kpv from overloading the generators.

Note: You are supposed to parallel the gen input. If you have the CV charging the battery directly, then you don't have to parallel that connection.

Click to expand...

The 18k Manual shows that "Gen Rated Power (kW): The battery charge power can be limited based on the detected LOAD consumption and Generator input power limitations."

I assume this means it will still try to split the generator power between the load and batteries, with priority on the load? This is what I have gathered from reading the manual: "When the generator is started, all the loads connected to the LOAD terminals will be supplied by the generator while still charging batteries. The pass-through relay on the generator terminal is 90A. When the generator is on, please ensure the total load and charge current does not exceed 90A."

DIYrich said:

Can't hurt.

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My understanding is if lightning or something similar hits my system, it could fry everything without these in place. I would think not having them on an expensive system is pretty risky, or are the components in play pretty tolerant?

DIYrich said:

Some way to stop power in the string is helpful. Let's say you want to move a string from one MPPT to another. Disconnect (or RSD) lets you do that during the day.

Click to expand...

I think I'll implement these, I'm pretty sure this is NEC 2017 code anyway, which I will need to adhere to in Idaho if I plan on getting the off grid system permitted.

I am building a similar system myself now. 18kpv and 56 Hyperion 395 watt panels. The final configuration will be 4 strings of 14. Only 3 of 4 strings will be set up now. We will be building an off grid home in a couple years and move the equipment and do the full install then.

Strings of 12 would be fine. You have a lot of panels so unless you buy more to max out the strings at 14 I wouldn’t sweat it. 12 panels gives you more combinations to work with as far as mounting. 1x12, 2x6, 3x4 etc.

I just got a string of 11 up today and running temporarily. I have IMO isolators (indoors) next to the 18kpv with midnight solar lightning protection. Outside near the arrays I have another IMO. It is code to have isolating means within sight of the array as I recall. These portions of code are new to me and I am trying to decipher them. I like having them in both locations as it is safer and handier to be able to turn that switch and know it’s off.

I have a chargeverter for future use, but only have a 3500watt generator at the moment. In a pinch I could use it manually. I think as long as you set the max gen current for your gen size you will be fine.

Have patience. It’s fun, but a lot of work.

A couple pics of the imos.

The 100A breaker you show is a branch circuit breaker, looks like you would back-feed it from inverter load output.
If you do, it is best to have a retention device, so the breaker can't pop out and have exposed contacts (some models like QO, but Homeline is more covered.)

When I paralleled multiple inverters I did try 2x 70A 2-pole plug-in branch circuit breakers, but they caused issues with unbalanced pass-through current from the grid.

the question will be how your 3x inverters behave. My Sunny Island simulate resistance and voltage droops with current, facilitating sharing of current. Victron specifies output wire resistance must match exactly.

My problem was QO270 resistance differed between breakers, and with 60' of 6 awg wire matched to within an inch, I still saw 3:1 current imbalance. Schneider Multi-9 63A DIN rail breakers matched within 10%. Midnight/CBI breakers matched perfectly.

So my suggestion is a box with DIN rail and either CBI or Carling magnetic-hydraulic breakers (which only need to be 0% or 5% respectively higher than max continuous current, not 25% higher like thermal-magnetic.) Then you can feed combined output to main lugs; with redundant inverters and batteries, likely no need for generator bypass.

For the panel shown, you can get 70A, 100A, or 125A main breaker which fits in the larger knock-out.

Or just connect to the main lugs. Does manual say a breaker is required? You would want to size a breaker 25% above inverter continuous current, and then it is likely to never trip anyway. Unless excessive current fed from grid or gen input.

GFCI breakers or outlets for wet locations are good shock protection.
AFCI breakers are now code for 20A circuits. Combined AFCI/GFCI is available.
All can be 1-pole or 2-pole.

Are you planning to start out with a 12 slot panel fully stuffed?
Start with a bigger panel.

Consider an interlocked "Generator" breaker" (sliding sheet metal blocks main breaker) so you can run the place off generator if you need to take inverter offline.

Ground rod - typically two are now installed, at least 6' apart.
Bond also to all water and gas lines. Bond hot & cold together at water heater. Bond to foundation steel if accessible, RV frame in the interim.

I was required to use 4 awg to water pipe for 200A service, not sure if same for lower amperage system. Other connections 6 awg was allowed (standard ground wire for 200A.)

Bond PV panel frames to inverter chassis!
People keep not doing that, and people keep getting shocked.

RyGuy said:

I am building a similar system myself now. 18kpv and 56 Hyperion 395 watt panels. The final configuration will be 4 strings of 14. Only 3 of 4 strings will be set up now. We will be building an off grid home in a couple years and move the equipment and do the full install then.

Click to expand...

Yeah, sounds like a very similar plan. The biggest variable for me at the moment is a good DIY racking system that falls within code and has engineered designs stamped that doesn't cost more than the panels lol...

RyGuy said:

Strings of 12 would be fine. You have a lot of panels so unless you buy more to max out the strings at 14 I wouldn’t sweat it. 12 panels gives you more combinations to work with as far as mounting. 1x12, 2x6, 3x4 etc.

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Agreed. One broke in shipping so I have 71 to deal with unless they can ship a replacement without breaking that one. I hear that's a tough deal.

RyGuy said:

I just got a string of 11 up today and running temporarily. I have IMO isolators (indoors) next to the 18kpv with midnight solar lightning protection. Outside near the arrays I have another IMO. It is code to have isolating means within sight of the array as I recall. These portions of code are new to me and I am trying to decipher them. I like having them in both locations as it is safer and handier to be able to turn that switch and know it’s off.

Click to expand...

Congrats. I think I'll put them in both locations as well.

RyGuy said:

I have a chargeverter for future use, but only have a 3500watt generator at the moment. In a pinch I could use it manually. I think as long as you set the max gen current for your gen size you will be fine.

Click to expand...

I think the 18k requires 240v generator input from my reading? Can it be configured to accept the 120v from a smaller inverter generator? Looks like I stepped in it thinking the parallel kit for the Predator 5000 is 240v with a NEMA 14-50 outlet, but it's not... it's 120v, so if the 18k requires 240v I'll have to get a Chargeverter or another generator.

RyGuy said:

Have patience. It’s fun, but a lot of work.

Click to expand...

Thank you for all the feedback. I may make a video walking through my process at some point to help others. Not a lot a full install videos with this newer hardware out there for bigger systems.

Appreciate all the feedback

Hedges said:

The 100A breaker you show is a branch circuit breaker, looks like you would back-feed it from inverter load output.
If you do, it is best to have a retention device, so the breaker can't pop out and have exposed contacts (some models like QO, but Homeline is more covered.)

When I paralleled multiple inverters I did try 2x 70A 2-pole plug-in branch circuit breakers, but they caused issues with unbalanced pass-through current from the grid.

Click to expand...

Good point. I bought a panel yesterday. Went with the Leviton 40 slot panel with a 200A main breaker: https://www.homedepot.com/p/Leviton...-Main-Breaker-RD0-LP420-BDR/323276278#overlay

The thought being I'll use this for all my branch circuits for now, run a 60A breaker with 6AWG wire to the single 18k for now, leaving the main breaker/lugs free for connecting a future 200A panel where I combine multiple 18k (3 total in theory). Let me know if this sounds off in any way, just picking up bits and pieces as I go. I noticed most diagrams show the 60A and 6AWG cable on the 18k, not sure if a 70A breaker is a better idea with 4AWG cable (these are harder to come by). Per @DIYrich comment, 12k/240 = 50A which is the rated 18k output, and 12k*1.25=15k, leaving 15k/240=62.5, so in theory the 60A breaker is 2.5A undersized if you are following the rule of thumb but it seems like the 60A with 6 AWG is common anyway?

I'm not married to this Leviton panel yet.., just thought it had some unique features. So please criticize if you see the need.

Hedges said:

the question will be how your 3x inverters behave. My Sunny Island simulate resistance and voltage droops with current, facilitating sharing of current. Victron specifies output wire resistance must match exactly.

My problem was QO270 resistance differed between breakers, and with 60' of 6 awg wire matched to within an inch, I still saw 3:1 current imbalance. Schneider Multi-9 63A DIN rail breakers matched within 10%. Midnight/CBI breakers matched perfectly.

Click to expand...

This is something I haven't considered, hopefully the 18k units don't suffer from the same issue. I'm in North Idaho and have property with zero shading from Trees, etc.

Hedges said:

So my suggestion is a box with DIN rail and either CBI or Carling magnetic-hydraulic breakers (which only need to be 0% or 5% respectively higher than max continuous current, not 25% higher like thermal-magnetic.) Then you can feed combined output to main lugs; with redundant inverters and batteries, likely no need for generator bypass.

Click to expand...

The panel I bought comes is compatible with these Thermal Magnetic breakers, don't see a max current rating listed in the specs. I'll have to dig to see.

Hedges said:

For the panel shown, you can get 70A, 100A, or 125A main breaker which fits in the larger knock-out.

Or just connect to the main lugs. Does manual say a breaker is required? You would want to size a breaker 25% above inverter continuous current, and then it is likely to never trip anyway. Unless excessive current fed from grid or gen input.

Click to expand...

"Or just connect to the main lugs", are you referring to skipping a breaker on the load panel side since the 18k has one?

Hedges said:

GFCI breakers or outlets for wet locations are good shock protection.
AFCI breakers are now code for 20A circuits. Combined AFCI/GFCI is available.
All can be 1-pole or 2-pole.

Click to expand...

Good to know this now That's going to get expensive per the prices I'm seeing on AFCI/GFCI.

Hedges said:

Are you planning to start out with a 12 slot panel fully stuffed?
Start with a bigger panel.

Click to expand...

That was the original thought, thinking a full panel now to get some better future proofing.

Hedges said:

Consider an interlocked "Generator" breaker" (sliding sheet metal blocks main breaker) so you can run the place off generator if you need to take inverter offline.

Click to expand...

This a good idea. Is this comment talking to once I have multiple 18k units in place? The thought being to run the generator breaker separate from the 18k and only to load panel and not bother using the 18k generator input?

Hedges said:

Ground rod - typically two are now installed, at least 6' apart.
Bond also to all water and gas lines. Bond hot & cold together at water heater. Bond to foundation steel if accessible, RV frame in the interim.

Click to expand...

Yes, learned this last night. I'll be buying as second grounding rod. How do you bond to water lines if they are all PEX and poly these days? The only metal is the copper/brass fittings in a few spots. Since this is all in a shipping container, bond to the shipping container frame and the RV frame, or just one of the other?

Hedges said:

I was required to use 4 awg to water pipe for 200A service, not sure if same for lower amperage system. Other connections 6 awg was allowed (standard ground wire for 200A.)

Click to expand...

Interesting, wonder what the logic is here?

Hedges said:

Bond PV panel frames to inverter chassis!
People keep not doing that, and people keep getting shocked.

Click to expand...

Planning do this once I get to the panel. I'm assuming you mean a ground bond?

The 18kpv need a good 240v generator. That's why I got the chargeverter. It can use a cheaper generator. Even 120v if an adapter is used. It will be a while before I decide whether I need an expensive generator.

I ordered 1 extra panel. One was cracked. Not sure if that was from shipping or me. Should still work. Luckily its a backup.

Racking is expensive! I have 2 of the eg4 bright mounts and a DIY moveable wood rack that holds 3 panels. I am constructing a DIY metal rack on my shipping container using 1.25" galvanized pipe and fittings available through lowes. It blasted expensive even diy with this setup. 10' of pipe is $50. Fittings are $8-15 each. Strut is $35-45 per 10'. Lots of fasteners and clamps etc etc....... I envy those in sunnier areas to the south that don't need as many panels in the winter. I will have huge excess in the summer and scratch by in the winter I believe.

Fyi, here in my area we only need engineering if a the structure is over 10' above ground. I was sure happy about that as everything else seems over regulated. Maybe the same for you?

Officient said:

I'm not married to this Leviton panel yet.., just thought it had some unique features. So please criticize if you see the need.

Click to expand...

Is utility grid involved?
If grid fed 200A main breaker and PV backfed the grid through this panel, one way to comply with NEC is "120% rule", 200A busbar x 120% = 240A, 240A - 200A main breaker = 40A PV breaker allowed at other end.

If no utility source, on your inverters, this does not apply. Just limit sources to 200A.


I put in Homeline panel with aluminum busbars years ago. Now I try to use QO exclusively; it has copper for 125A and up but aluminum for 100A and less. Aluminum is acceptable for use in most locations, but I've standardized on the Square-D QO series meant for residential/commercial.

Officient said:

This is something I haven't considered, hopefully the 18k units don't suffer from the same issue. I'm in North Idaho and have property with zero shading from Trees, etc.

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If you have pass-through from grid, or a very large generator, and are counting on resistance dividing current evenly, then some breakers are a problem.

As for paralleling outputs so they share the load, RTFM. If it requires exact match of wire length, some breakers (at least the QO270 I used) were a problem.

I've had better results with magnetic-hydraulic. They do not have a designed-in heating element.

Officient said:

The panel I bought comes is compatible with these Thermal Magnetic breakers, don't see a max current rating listed in the specs. I'll have to dig to see.

Leviton Branch Circuit Breaker, Standard 2-Pole 30 Amp, 120-Volt/240-Volt, Thermal Magnetic R10-LB230-0TR - The Home Depot

Leviton Circuit Breakers provide overload and short-circuit protection and feature an all plug-on design. All hot and neutral wires terminate at custom lugs in the panel, not at the circuit breaker, so

www.homedepot.com

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Thermal. Therefore you should not exceed 80% of rating for continuous load. OK for shorter periods.

Officient said:

"Or just connect to the main lugs", are you referring to skipping a breaker on the load panel side since the 18k has one?

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Yes, or having separate fused or breaker combiner box.
If 18kPV has output breaker, that is probably sufficient. You can combine 3x inverters with Polaris multi-tap connectors and land a cable on load center's main lugs. Or into main breaker, if you use this panel with breaker.

For a while, I used dual lugs on load center to parallel two inverters. Later I inserted magnetic-hydraulic breakers on DIN rail in another box.

Officient said:

Good to know this now That's going to get expensive per the prices I'm seeing on AFCI/GFCI.

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Easily $75 per pole.

Believe me, they are very inexpensive compared to a burned down house/emergency hospital admission to monitor erratic heartbeat.

At this time, AFCI is required by code for circuits up to 20A. Larger circuits are generally point to point, less likely to have splices or daisy chain. Less likely to be repeatedly overloaded.

GFCI is required for we locations including kitchen near sink, bath, garage, outside.

I've just installed 2-pole AFCI for some household circuits with shared neutral. Previously put GFCI outlets where I wanted 3-prong (old ungrounded wiring) but not for refrigerators. Eventually I plan to split things into half a dozen 120V circuits, 1 pole.

Shopping on eBay I bid on a lot of 10 pieces QO 20A combination AFCI/GFCI, got them for about $220 so $22 each!
There is a problem with counterfeits, so I tested them. Pushbutton self test, 9 worked 1 didn't, so I've requested partial refund.
Loaded with 40A, all 10 slow-tripped in about 30 seconds. So they are functional, not just a counterfeit containing only a switch.
I would like to fast-trip them with 120A, but that will need to be at full voltage because they contain powered electronics. (For passive breakers I set up a transformer that boosts current.)
What I haven't done is to test AFCI. I presume GFCI test button just bypasses 6 mA with a resistor. I should try that externally.
To test AFCI, maybe burn steel wool? That's one test for PV AFCI.

Officient said:

This a good idea. Is this comment talking to once I have multiple 18k units in place? The thought being to run the generator breaker separate from the 18k and only to load panel and not bother using the 18k generator input?

Click to expand...

Interlock selects between main breaker and one 2-pole breaker.
So I think parallel the "Load" outputs of however many 18kPV (they have internal breaker?), feed those into that 200A main breaker.
Feed generator into a backfed branch breaker. Install hold-down and interlock.

You can also use 18k generator input, it should be able to start generator, sync to it, use it as AC source.

Do NOT connect generator to "Load" input, only to "Gen" input or "Grid" input.
Maybe if no utility grid, you can feed generator into "Grid" input and AC couple additional GT PV inverters on "Gen" input. If you want more PV than fits on MPPT inputs.

Officient said:

Yes, learned this last night. I'll be buying as second grounding rod. How do you bond to water lines if they are all PEX and poly these days? The only metal is the copper/brass fittings in a few spots. Since this is all in a shipping container, bond to the shipping container frame and the RV frame, or just one of the other?

Click to expand...

I guess you don't. Water provides a conductive path. Fixtures (may) be made of metal. I could imagine running a ground wire to every faucet, shower, tub. But I'm not sure what code is, be sure to research that.

Imagine inverter feeds water heater or pump, fault electrifies water feed, you're in the shower with drain water making a path to earth.

The first (several?) Desert Storm deaths were soldiers electrocuted by taking showers.

Officient said:

Interesting, wonder what the logic is here?

Click to expand...

We've always done it that way?
Water pipe used to be the ground rod?

For 200A circuit, 6 awg is minimum ground.
But inspector dinged me for not having 4 awg to water pipe, and I replaced it.
But new 4 awg seemed just as big as old. I mic'd it, 0.204", was already 4 awg.
Both my solid bare spool and green insulated stranded wire were 4 awg, someone pointed me to the correct wire before I knew better.

Officient said:

Planning do this once I get to the panel. I'm assuming you mean a ground bond?

Click to expand...

I mean a copper wire that connects inverter chassis to frames of all PV panels. There are some methods to use PV mounting rails as a conductor so wire itself don't have to attach directly to each panel.

RyGuy said:

The 18kpv need a good 240v generator. That's why I got the chargeverter. It can use a cheaper generator. Even 120v if an adapter is used. It will be a while before I decide whether I need an expensive generator.

I ordered 1 extra panel. One was cracked. Not sure if that was from shipping or me. Should still work. Luckily its a backup.

Racking is expensive! I have 2 of the eg4 bright mounts and a DIY moveable wood rack that holds 3 panels. I am constructing a DIY metal rack on my shipping container using 1.25" galvanized pipe and fittings available through lowes. It blasted expensive even diy with this setup. 10' of pipe is $50. Fittings are $8-15 each. Strut is $35-45 per 10'. Lots of fasteners and clamps etc etc....... I envy those in sunnier areas to the south that don't need as many panels in the winter. I will have huge excess in the summer and scratch by in the winter I believe.

Fyi, here in my area we only need engineering if a the structure is over 10' above ground. I was sure happy about that as everything else seems over regulated. Maybe the same for you?

Click to expand...

I ended getting a Chargeverter from Current Connected yesterday, they have them in stock. I'll have to get a plug conversion sorted out as it 120v with the 30 AMP plug.

Do you see any issues with permitting going the DIY route? If the county requires a permit for the ground mount racking it will probably have to have a stamped engineering document with wind/snow loads specified. I'm hoping to avoid that as all the prefab solutions are pretty spendy

I was able to avoid engineering by splitting array into sections that fit no-permit structure size, 120 square foot footprint.
They may have wised up since; that was 20 years ago.