Snow, Rain, Frost, and Wind ground or roof mount?

[Snowynorth]

I'm new! My electrical knowledge is low! I appreciate the info I've read here, and those that have helped me.
Maybe the links below will help some others. I posted them in another thread, but I think they could help a few more.

About 7-8 years ago I met a guy who had a roof mount array on an acreage about 2 miles from me. The panels did shed snow fairly well. He had a steep pitch. The next year I was driving past his house and saw that the panels were down. I stopped and talked to him, and he told me it was because his roof was leaking, and a fix was needed. I decided then that there would be no roof array for me. I told him to use quad sealant, or hot tar to seal every penetration before re installing the panels. Or better yet install a ground mount. He had plenty of space, and wasn't lacking in funds. He went back to the roof, but did make sure it was sealed properly.

I don't know much about electrical, but I do know a couple things about nasty weather up here in Alberta. I also know a bit about expansion, and contraction, and a few other basic things about construction. The wife and I built 4 houses and renovated another 5 when we were younger. We lived in them long enough to be considered primary residence, and not subject to tax. Then sold them at a profit, and started again.

I was first thinking about the biggest panels I could get and using less of them, but knowing the stress, possible frame twisting, the metal frames wanting to expand and contract while being firmly mounted, and the support they would need with high wind speeds, and no roof behind them, I decided to go with 60 cell, or 120 cell 1/2 cut and nothing more. I think big panels withstand better on a roof, where I would never install, unless I absolutely had too. Because it's a ground mount, and exposed to the wind I am also going gap 12" +- between each vertical set of 3 to reduce wind resistance. The bottom will be 5' +- from ground level, to handle snow shedding.

For those in the snow and cold. Here are a couple links that could help you. We built 3 small cabins on screw piles at our hobby/party farm. I dug the piles in 12' for a reason.

Fence Post Keeps Popping Up? Here’s How To Stop Frost Heaves

If the winter frost heaves your fence posts, follow this guide to solve this problem once and for all.

bestlife52.com

https://www.cbc.ca/news/canada/calgary/frozen-pipes-homeowners-frosted-calgary-1.5051182
I understand the average person who hasn't dealt with it, but did municipalities not understand frost lines years ago? I'm glad I did.

Solar panels shine despite winter's blast, NAIT study finds

Five-year study by alternative energy experts shows snow has little impact on panels' effectiveness

www.nait.ca

I hope I wasn't to wordy. For the new folks like me, there is more to consider with solar, then the size, and configuration of your electrical system.

 

[Samsonite801]

Yeah, I decided to go with ground mount too to start out with for now, seems easier to service the panels and even will give a shady spot to hang out under on hot days...

 

[Ironman]

I'm with you on ground mounts being the best in our environment. But also I'm a big fan of steel roofs.
In my case, with an almost always western wind, south facing means my panels are edge on to the wind. I've also learned to build my buildings facing gable end into the prevailing wind, and the snow never seems to get any buildup on the roof before the wind takes it away.

 

[sunshine_eggo]

Advantages to roof mounts:

1. They don't take up any usable land area.
2. They may have shorter wire runs to equipment.

Disadvantages to roof mounts:

1. More expensive than ground.
2. Compromised array maintenance, troubleshooting and testing.
3. Rarely at the proper tilt.
4. Possible lack of suitable mounting area for a due South orientation.
5. May have insufficient cooling depending on distance from panel to roof surface. Adversely impacts panel production and life.
6. NEC2017+ requires individual module level shutdown adding ~$50 to the cost of each and every panel.
7. A PV related fire may impact your roof.
8. Harder to clean/de-snow if needed.

IMHO, if you have the space on the ground, it's almost silly to not ground mount.

 

[Samsonite801]

Just as a side note, I like what Ian did here on his barn where he just made the solar panels be the roof...

I know this wouldn't be perfect for every scenario maybe, but for a barn (or even a carport) it seems great.

 

[Snowynorth]

I'm with you on ground mounts being the best in our environment. But also I'm a big fan of steel roofs.
In my case, with an almost always western wind, south facing means my panels are edge on to the wind. I've also learned to build my buildings facing gable end into the prevailing wind, and the snow never seems to get any buildup on the roof before the wind takes it away.

I have steel roofs on all 3 of our new cabins. One side of the big cabin roof is 20'x 56' with a 5/12 pitch facing directly south, out to a field with no tree shade. My solar component shed is 15' off of the cabin. I have 4 awg cable trenched well over 200 ft to where the ground mount will go. That's how much I like roof mounts.

 

[MichaelK]

For my workshop I did both. So I have a four-panel mount on the roof and a four-panel ground mount. The workshop has a shed roof, so the pitch is only 1:10. I built a triangular frame out of unistruts to hold the panels. I then bolted unistrut rails on the roof perpendicular to the array frame. So, the rails are bolted to the roof, and the array is bolted to the rails. It was straightforward to make and install. What I find though is that the ground mount makes spot checks on wiring connections very easy. I have to get a ladder to check the roof mount.

The ground mount is a rotating mount like what I always show in my pics. The advantage of this mount is I can rotate it East in the morning and West in the afternoon for more power. It's not motorized, I just turn it by hand. I find that the rotating ground mount ~doubles my available sunhours when tracking the sun.

The other advantage of the ground mount is it is seasonally adjustable, and when set at the winter angle, it sheds snow the same day without me having to do anything.

 

[upnorthandpersonal]

In case you can't dig into the ground easily (like me because it's all bedrock), you can use something like these if you can find them:

Get them as deep as you can, then cover the whole thing with tons of gravel. This is mine:

Build thread:

DIY ground mount

Keeping in line with the whole low-cost solar system, building my own braided bus bars, etc. I thought I would see what it takes to build a low-cost ground mount for those 500W 96 cell panels (1310mm x 1956mm). My goals were to make the whole thing simple to build, with minimal tools and simple...

diysolarforum.com

 

[Snowynorth]

In case you can't dig into the ground easily (like me because it's all bedrock), you can use something like these if you can find them:

Get them as deep as you can, then cover the whole thing with tons of gravel. This is mine:

Build thread:

DIY ground mount

Keeping in line with the whole low-cost solar system, building my own braided bus bars, etc. I thought I would see what it takes to build a low-cost ground mount for those 500W 96 cell panels (1310mm x 1956mm). My goals were to make the whole thing simple to build, with minimal tools and simple...

diysolarforum.com

There are people who use the 2000 and 4000 lb concrete stacking blocks. The ones that are seen separating fancy rock, and dirt etc at the landscape supply yards. They are quick to set, but equipment is needed. It's not how I'm going to do it, but if I couldn't get well below frost I would rather than drilling.

 

[Wellbuilt]

I have these 3 concrete pads to mount some panels on 3’x6’6 x8” thick .
They are 800lbs each I’m going to run 9 panels it’s going to be 12’ high and 20’ long .
I’m going to make them flush with the ground .

 

[Snowynorth]

I think for 20' long you should have 6 anchors. Keep us posted. I'd like to see the finished product.

 

[Snowynorth]

One thing to remember if you have frost, you are better off staying above ground if you can't dig below the frost line. I built a 2 tier deck off of my house. I couldn't afford the extra expense of deep piles at the time. The county didn't want to approve it. The inspector said piles only. My Kid worked for a company that had a structural engineer. He stamped my drawings. So much for the inspector. The deck has been there for 16 years. It moved very slightly a couple times, then went back into the original place. I haven't even needed to re tighten any screws.

 

[Snowynorth]

It is the freezing moisture frost under poorly placed piles that push them up, and they don't go back down. If you are well below the frost line the frost pushes sideways in and out, not up.

 

[Snowynorth]

If you are putting pipe in the ground "below the frost line" in cold climates it's a good idea to pour cement inside up to a couple inches above ground level, unless you are using very heavy schedule pipe. Even then I would pour in the concrete if it was mine. It counteracts the side pressure from the frost, so the pipe doesn't buckle. I have done this, and built a breathable hat on top to allow the cement to cure, and keep out rain. Then you should weld on, or otherwise seal the top with a cap. Use big stretch or quad, that don't shrink and crack, and make sure it's well sealed. I've seen rain accumulation that built up and froze inside schedule 80 pipe up here, and it split it open, like it was a plastic bag. Others have told me they have seen schedule 40 do the same thing.

 

[Snowynorth]

I have these 3 concrete pads to mount some panels on 3’x6’6 x8” thick .
They are 800lbs each I’m going to run 9 panels it’s going to be 12’ high and 20’ long .
I’m going to make them flush with the ground .
View attachment 82555

When you anchor make sure you drill right through the concrete, and use heavy redi-rod or bolts. Put a good size chunk of 3/8 to 1/2" plate steel on the bottom and top to spread out the pressure, Secure with big washers and big nuts. Also make sure your mount to the poles above are super heavy duty. The top of your cement pads is the fulcrum point, especially the back longer poles. It's like sticking your arm out and someone pushes down near your shoulder. It's not to easy. Then they push down on your hand. It's easy. The top of your pole is your hand, the bottom is your shoulder. If you have no wind which I doubt, forget the above.

 

[Wellbuilt]

Yes that is the plan , I’m thinking 4x6 treated lumber and steel brackets mounted to the top and front
and to the top and back side .
I’m on the top of a Mountain in the middle of nowhere , and there is lots of wind but it comes out of south west and will hit from the front so there is not a lot of lift from behind .

 

[12VoltInstalls]

t is the freezing moisture frost under poorly placed piles that push them up, and they don't go back down

No it isn’t. It’s the frost grabbing the piling or footing and pulling it up, unfrozen dirt falls underneath and it doesn’t always go back down

That is why tapered pre-cast footings work so well- they don’t pull up

 

[crossy]

IMHO, if you have the space on the ground, it's almost silly to not ground mount.

We have our 10kWP of panels on our car port so they don't take up any of our limited land (only about 1/2 an acre).

Our house roof is a "feature" and there is no way Madam would permit panels up there. It's also Thai style with curved rafters so mounting would be a nightmare (the pitch would be way too steep anyway).

Easy to maintain without loads of climbing (OK slightly harder than true ground mounting) and the inverters live under the car-port roof out of the weather (they are IP65 and fanless).

Of course we are only a few degrees above the equator so the panels are flat on the roof but it shouldn't need too much engineering to apply tilt.

At least we don't have to worry about shedding snow

 

[sunshine_eggo]

We have our 10kWP of panels on our car port so they don't take up any of our limited land (only about 1/2 an acre).

Easy to maintain without loads of climbing (OK slightly harder than true ground mounting) and the inverters live under the car-port roof out of the weather (they are IP65 and fanless).

Of course we are only a few degrees above the equator so the panels are flat on the roof but it shouldn't need too much engineering to apply tilt.

At least we don't have to worry about shedding snow

Pffft. Not a roof. You just have a ground mount you can park your cars under. ?

 

[sunshine_eggo]

I am fighting the urge to replace my aluminum awning over the back porch with one constructed from SanTan panels. 12x30', and it's almost a perfect fit as-is for 5kW. Due South, mostly favorable shading and the slight tilt makes it almost perfect for summer solstice.

Since it's not a "roof" and considered temporary, no individual module shutdown requirement.

WTF am I waiting for? A shorter project list...