Panel wiring

[BackwoodsEE]

You mentioned a "fixed mount facing south." Is that a ground mount? If so, and if you mount the grid-tie inverter outside so that no PV circuits go through the wall of a building, you don't need rapid shutdown. (And if the "building" is a dedicated solar equipment shed, you still don't need rapid shutdown for NEC 2017.)

If PV circuits enter a building but the interior conductors to the inverter are less than 3 feet long, you might not need rapid shutdown, either, as that is the maximum length of an "uncontrolled conductor" inside a building per the code. Less clean of a demarcation between PV outside and regular circuits inside, though. I've read of a case where the AHJ just wanted the inverter outside without rapid shutdown and that was that.

All this is academic if it's a roof mount. Then you are stuck with the rapid shutdown BS unless you use microinverters or optimizers, which satisfy the rapid shutdown requirement inherently.

[max2k]

Ah, this is making more sense now.
Sounds like the solar edge optimizers outputs are wired in series?

I'll look at the micro inverters too..


Thank you!

If you don't have much shading issues you can use SMA Sunny Boy 3.8 which has 2 separate MPPT inputs for your 10+9 configuration and can be had for $1,300.

SMA sells Rapid Shutdown System which consists of roof box and small 'controller' box with buttons installed on the wall at the ground level. It requires 5 wire control cable connecting the two but the cable is not specific for this system. The whole thing runs off 12V supplied from the box on the roof and is completely independent from the inverter. Roof box goes for around $300 and controller- $55 + the cable of course. Roof box has 2 channels A & B to control both strings in your case as it is single inverter.

If you go this route you're looking at approx $1,300 + $355 + $100 = $1,755.00 cost

[Dave T]

Yes, somehow I noticed that. Kind of irks me when companies pull stuff like that. Use weird custom stuff. Leave out parts / features you can't do without. Just to make it look like their system is a better price.

Looking over more stuff. I have to sell the stuff that isn't right for my needs, to get the funding for the correct equipment.

[Dave T]

Anyone seen / know of these?
solarpanelsplus.com/products/solar-microinverters/

[sensij]

Anyone seen / know of these?

solarpanelsplus.com/produ...icroinverters/

No, but the link on their webpage to their CEC test report shows some bad photoshopping of their name on top of the results of Northern Electric and Power's BDM-250-240A microinverter. They might all be from the same factory... Renesola's Replus 250b looks awfully similar too, but at least it has authentic test data. I wouldn't really trust any of it on my roof.

[Dave T]

Oh, wow, lots of good info. Yes, ground mount is my preference. I could easily have a solar shed thing to put the inverter in, if that removes the expense of that shutdown thing. This stuff has changed a LOT since I last investigated any of it.

[ButchDeal]

Oh, wow, lots of good info. Yes, ground mount is my preference. I could easily have a solar shed thing to put the inverter in, if that removes the expense of that shutdown thing. This stuff has changed a LOT since I last investigated any of it.

ground mount is going to cost more than rapid shutdown. There is additional material involved in ground mount as well as more labor.

[BackwoodsEE]

ground mount is going to cost more than rapid shutdown. There is additional material involved in ground mount as well as more labor.

I'm in the middle of setting up my 24-panel ground mount, and "more labor" is putting it mildly. It's an IronRidge racking system, 8 x 24" concrete piers 4' deep. Once you get a few inches below grade, my ground turns into a combination of "dust and boulders," as my son put it. The auger wound up making craters instead of neat holes, and the last couple of days I spent shoveling tons (literally, tons) of that dust and boulders around cardboard sonotubes. My tractor helped, but it was still a lot of work.

And the expense? I hate to think of it, from the Bobcat rental to paying my very skilled buddy to run the thing to the IronRidge materials to the 400 lbs. of mechanical tubing to the concrete truck. Oh, and don't forget the fat cable and conduit leading to the array.

Also, a solar shed isn't free. You have to consider the security issue, too. Some very expensive equipment sits inside, and hardware-store steel sheds are flimsy little things. Also, be mindful of the NEC working space requirements.

If I had a big properly oriented roof without shading problems, I'd happily buy whatever rapid shutdown BS box I needed and be on my way.

[SunEagle]

I'm in the middle of setting up my 24-panel ground mount, and "more labor" is putting it mildly. It's an IronRidge racking system, 8 x 24" concrete piers 4' deep. Once you get a few inches below grade, my ground turns into a combination of "dust and boulders," as my son put it. The auger wound up making craters instead of neat holes, and the last couple of days I spent shoveling tons (literally, tons) of that dust and boulders around cardboard sonotubes. My tractor helped, but it was still a lot of work.

And the expense? I hate to think of it, from the Bobcat rental to paying my very skilled buddy to run the thing to the IronRidge materials to the 400 lbs. of mechanical tubing to the concrete truck. Oh, and don't forget the fat cable and conduit leading to the array.

Also, a solar shed isn't free. You have to consider the security issue, too. Some very expensive equipment sits inside, and hardware-store steel sheds are flimsy little things. Also, be mindful of the NEC working space requirements.

If I had a big properly oriented roof without shading problems, I'd happily buy whatever rapid shutdown BS box I needed and be on my way.

Oh boy. I have something to look forward to next year. I planned on a ground based system sized between 6k and 8k watts. My home will not have a southern facing roof but I will have over 2 acres without and shade close to the home for the ground mount.

The problem I see with a solar shed would be the size needed for 20 to 26 panels all facing south. That will be a really big shed and may easily cost more than the ground mount hardware and installation I guess I won't know how bad my soil is below ground until I do some digging. I don't expect big rocks but I could easily hit a limestone layer that will make hole drilling a problem.

[BackwoodsEE]

The problem I see with a solar shed would be the size needed for 20 to 26 panels all facing south. That will be a really big shed and may easily cost more than the ground mount hardware and installation

What I meant by solar shed was just a detached little structure big enough to hold the equipment. No panels mounted on it. Yes, one big enough to hold all those panels would be a big structure indeed! Also, I don't know that panels mounted on a dedicated building that big would qualify as "ground mounted" for the NEC 2017 exception.

[SunEagle]

What I meant by solar shed was just a detached little structure big enough to hold the equipment. No panels mounted on it. Yes, one big enough to hold all those panels would be a big structure indeed! Also, I don't know that panels mounted on a dedicated building that big would qualify as "ground mounted" for the NEC 2017 exception.

I would imagine that any roof mounted panels (house or shed) would not qualify as a ground mounted system. If rapid shutdown is required for a shed I would guess that would be determined by the local fire department codes.

I was just trying to compare the costs of a ground mount system between 6k & 8k compared to a roof top installation on a none residential building or shed. Both the building and ground mount system would be required to meet the 130MPH wind code so it might cost more for the ground mount system (especially if the digging ran into issues) then a building with a roof top system with rapid shutdown. But that building would need to be pretty big and probably require some type of solid foundation or footing to meet wind codes.

Too soon to know until I go dig my first fence post hole.

[Dave T]

Ok.... I have a very large backhoe. Pretty much required to dig anything in my yard. I built the house entirely, literally, from clearing the trees, to the shingles on the roof, and everything in between. The only things I hired out was blasting, drilling the well, and pouring the slabs for the basement and garage.
The ground mount area likely has solid rock just under a thin layer of dirt, there should be a way to bolt or tie whatever structure to that. My roof ridge line is perpendicular to the direction that the panels would want to be mounted, so ugly / nasty to arrange them. Also, snow, maintenance, [of panels or roof] etc. would be a nightmare. Some of the roof gets shade, and undesirable stuff [moss & lichen] grows on it, so shading it more with panels doesn't seem like a good idea, as that stuff ruins the shingles. I'll have to look into the rules / code for mounting them on a ground base. Anyone have links to information on that stuff? I probably was under thinking that part some, but that doesn't change the situation...
If it all ends up getting too spendy, I'll just sell the stuff off if I can't get a decent ROI.

I am not thinking of building a shed big enough to mount the entire array, just a weatherproof enclosure / small "shed" that an inverter could be mounted in. No, I wouldn't buy some cheap thing that you could push over. I was also planning on a shed for equipment near the area, and there would be space in it that would allow for an inverter and space to work on it. It would likely be between the array and the garage end of the house anyway. There will be conduits running to that shed regardless.

[Mike90250]

you might be able to cantilever the panel rails over the sides of the shed ?

[ButchDeal]

you might be able to cantilever the panel rails over the sides of the shed ?

Ha. We had a request for that on a homedepot shed of only 8X10 to have 4 foot cantilever overhang on 3 sides. Customer had looked up the specs on ironridge xr1000 rails and was sure it was ok because ironridge said so.
We tried to explain that that makes the shed into a glider and we are not licensed to manufacture air craft...

[Dave T]

I just found these: SMA Sunny Boy 240-US-99-10 Inverter

Made in USA, not china. Have to use their AC cable, but the DC side can have the MC4 connectors my panels have.