Ground mount costs?

icarus · October 2019

I am consulting on a grid tie project on a remote site, as noted earlier. I am wondering if anyone has a ball park cost difference between “normal” roof mount grid tied systems in the 5-10 kw range, compared to a similar sized ground mount. I am interested in potential ground mount so that the PV can be easily cleared of snow in the winter.

Tony

Estragon · October 2019

My 5.5kw (22 x 250w) racking, which I mounted on a flat roof, was ~ $2,800. That was 5yrs ago, but similar racking is about the same these days.

Seems to me it's roughly 2x the cost of fixed mount rails on a sloped roof for the racking. At least some of the extra rack cost would likely be offset by extra labour and materials to deal with roof penetrations, working on a sloped roof, etc.

Dave Angelini · October 2019

I feel it is about 30% more after all is said and done for a ground mount. Not much more to have it track which would not be good for you with unattended snow. Just basic handyman skills are required on the ground. Different story up on a roof and liability insurance and all of the other worries that are not there on the ground. So, 30% more for the racking on the ground but much stronger that what a roof mount is with wiring, pipe, cement, and rebar.

The only time I have done roof mounts is in the jungle/forest where it is too expensive to maintain the growth. Always try and talk offgrid folks out of weakening a roof for solar panels. Other reasons also. Good Luck on this one.....Still seems crazy to me

MichaelK · November 2019

My latest rotating ground mount design took about 400$ of steel and accessories to build (myself) an array holding four 250W panels. Mostly unistruts and schedule 40 steel pipe. Amusingly, I payed 400$ out the door for those panels from Ebay with local pickup. So the framing for my 400$ worth of panels cost 400$.

706jim · November 2019

I had roof mounted panels for 24 years. Seemed to make sense at the time (didn't want them stolen).
I've since changed to ground mounted panels, three against a deck and another three on a 4 x 4 A frame. Cost was couple hundred for the A frame but I couldn't be happier. My newly shingled roof has no holes in it and I don't have to climb up there to clear snow or check connections. So it needn't cost a fortune to put them safely on the ground.

MichaelK · November 2019

Here is a pic of my five

Image: https://us.v-cdn.net/6024911/uploads/editor/fr/tc9uolva6gr4.jpg

V1.5 arrays from the back, which will give you an idea of the construction. Most of the construction is galvanized steel. Two points to caution about. Whenever welding galvanized steel, you need to be careful not to inhale any of the zinc fumes, to prevent zinc poisoning. Secondly, the steel has to be painted to prevent galvantic corrosion between the zinc surface, and the aluminum frame. The design is evolving over time, and my newest V4.0 design is being welded together now.

westbranch · November 2019

Have you got a picture taken at close to 90-* to the back? It looks like they are 2 dimensional , tilt & rotate manually?

So each array is 900W NOMINAL

WaterWheel · November 2019

I have to agree with Dave that a ground mount costs about 30-40% more but is much easier to mount the panels and wire up. In addition a ground mount is easier to inspect, clean, and modify if you ever want to change out the controller input voltage.

geosierranevada · November 2019

About $ 1000.00 worth of steel and sch 80 pipe at today's prices. Alot of cutting, drilling and welding. 20 - 245 watt kyocera panels. Summertime I run all three flat and winter drop them down so the snow will somewhat slide off. I turn and tilt to the South in winter.
Enjoy Thanksgiving George

icarus · November 2019

George...

You don’t happen to have any drawing of your design that you would care to share? PM me if you would if you wish to speak about this.

Tony

geosierranevada · November 2019

Tony,

I did not draw any thing up, but I will post some views of the framework before panels installed. The first two I built 17 years ago and there are 6 panels on each as you can see. Originally I had 8 BP 120 watt panels on them and there was too much flex on the racks. Cracked 3 panels, reinforced racks and solved the flex issue. BP bought back my 16 panels and now have 20 Kyocera's and built the rack which holds 8 panels. I will take closer pictures of the pivot points when I can ( we are away from home and it just snowed 3 ft in the last 36 hours ).
These pictures of the rack are all I have for now. George. Have a nice day

geosierranevada · November 2019

geosierranevada · November 2019

That is all I have for now. Everybody have a good rest of the year. George

mike95490 · November 2019

Are the PV racks your own design, or engineered factory racks ?

icarus · November 2019

Thanks George...Tony

geosierranevada · November 2019

My design, pipes are concreted in, steel is 2" x .25 angle iron, some 2" x 3/16 strap and etc.

George

Dave Angelini · November 2019

Looks small on the pipe for that size array. You can't buy one like this because it will not hold the snow and definitely not snow and wind for very many years.

geosierranevada · November 2019

That rack has had 4 ft snow on it and 70 mph winds - but you are the expert.

Have a nice day. George

Dave Angelini · November 2019

You also.
If it works for you that is great. Inspector will not let me put more than 125 square feet on a 6 inch pole. Just math, physics and basic engineering.

MichaelK · November 2019

westbranch said:

Have you got a picture taken at close to 90-* to the back? It looks like they are 2 dimensional , tilt & rotate manually?
So each array is 900W NOMINAL

Yes, you are correct, the arrays can track left to right, and are also seasonally adjustable. They each hold three 300 watt panels. Here's a pic of the completed array just before adding my panels, about 3 years ago. When I built the V1.0 design, the flimsyness of the Z axis become apparent, as GSN also mentioned, so I added the trusses on the back side. I kept on making incremental improvements till I got to the fifth version, pictured here. They have survived winter storms that have toppled big oaks on my property, like those in the background.

Next is a pic of my V2.0 design (1000W), which I'm embarressed to show. It utilized bushings rather than hinges, and although I think it's a robust design, the assembly of the completed array in-situ was just too challenging for me. I have to say I think the final assembly is crap, though it does in fact act very sturdy. If you look very closely at pic #2, you can see my finished V3.0 design sitting on the ground in-between V2.0 and my truck. That fixed angle array is going on top of my little workshop, which is the room on the left side of pic two. It is also designed to hold four grid-tie panels.

My V4.0 design holds 4 grid-tie panels (1000W), and is made of 4 vertically oriented unistruts. That's what I'm building now. My V4.0 design is the culmination of all the mistakes I made from V1 through V3. I getting around all the problems with previous designs by making it more modular. The major subcomponents, like the trusses, will be bolted on at the last stage, instead of welding. That way all the subassemblies can be carefully fitted together on my garage floor, then bolted together once the array is being placed into position. Sorry if that is too verbose. I'll have pics next spring when I bring this newest array online. BTW, the V4 design could be scaled up to hold six grid-tie panels, by scaling up pipe diameters and numbers of unistruts. But since my V4 array will bring my total watts to ~7500, I think I'm done building arrays.

Image: https://us.v-cdn.net/6024911/uploads/editor/cf/57d5tn3lap69.jpg

geosierranevada · December 2019

Dave,

It is a different world up here in the Southern Sierra, the Building Inspector showed up while I was fabricating the last panel rack and he did not want to look it over. The only thing he gave me a hard time about was my lack of having a sign that says electric shutoff. On another note, I was going for a final inspection on my 40 x 60 metal barn, inspection was supposed to be in 3 days ( had the bolt tork guy lined up )
And Inspector called and told me he was too busy and couldn't come up, said it would be six weeks. I told the inspector where he could go
And cancelled inspection because it was not timely ( Fire Marshall passed it ). That is what it is like up here. Sorry I sorta gave you a hard time!

Have a nice day. George

Dave Angelini · December 2019

Hi George,
I have had my land in the southern Sierra for close to 30 years. We live outside in the foothills near Mariposa. There is a pix link on my web page below.

I am in business and have well over 200 offgrid homes under my belt. I design to the building code or better, inspected or not.

I did not mean for my comment to be an issue but rather a source of my experience. It has stopped raining so time to go out for a walk.

Ground mount costs?

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