Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
So you don't recommend this approach?
Complete Off-Grid House - 3000 sqft Ranch - Michigan
- Thread starter Over9000
- Start date
So you don't recommend this approach?
Daddy Tanuki
Emperor Of Solar
the forms were 40' but they were pouring roughly 4 meters (12 feet ish) on one wall per day and by the time they made one round they could pour on the then 4-5 day old concrete for the next 10-12 feet. they had some of the longest lobo chin vibrators I have ever seen could reach to the bottom of the mold and the cable was sectional so you could add length and was powered off of stationary 3 or 4 hp gasoline engines. add 4 together and you reached the bottom, as the mold got fuller you simple unscrewed and removed a section (ofr you moved the motor back out fo the way)
Daddy Tanuki
Emperor Of Solar
he is just saying you need to calculate for this. so either get a structural engineer to crunch the numbers for you or go bat feces crazy and overbuild it. i would have a engineer do the load calcs and materials sizing then go bat feces crazy because I love overkill on a project.
I do not know what the wind is like in your proposed location, but my first PV array here at fuji was a temporary setup I built with scafolding pipe... 3 years later when I moved the panels to their new home on top of the shop i found that some of the scaffolding pipes had deformed from wind load... I took note and added additional bracing and more pipes to my roof mount.... on something like this its adds to the cost, but with what you are investing into the system it is worthwhile to go a little crazy on the support structure.
Over9000
3rd Shift Ass. Manager @ 2nd-Hand Adult Toy Store
I'm pretty sure I could do the load calcs, strength / torsion / compression / flex analyses and figure out what the maximum of all normal forces and then multiply it by a safety factor.
Daddy Tanuki
Emperor Of Solar
pretty sure thats all he is alluding to. (but double check with him). as long as you brace it properly it will hold up like I said I added a couple of braces to my panels after moving them to the shop roof and problem solved as far as pipes deforming.
Daddy Tanuki
Emperor Of Solar
sorry missed a bunch in the middle, what are the specs of your SCC? thats all that matters...
OffGridForGood
Catch, make or grow everything you can.
Naturally, however an unsupported cantilever will require a very large section with this many panels - while a braced one will be far smaller and less expensive. We don't know anything yet about the ground conditions either - which needs to be part of the analysis.
Just trying to open the OP eyes to some possiblities. It is like thinking of a series of trusses to span your garage roof rather than beams, the trusses will be lighter and more slender because they are more efficient at transfering the loads. Lighter memebers are typically less expensive.
Brucey
Velcro Man
If this is using the Mt solar design tool that's already engineered by them you don't need any extra supports. But take a look at the numbers given for the footings for those four uprights it's going to be a significant volume/mass of conrete.
Also is a 28 foot max tilt height going to affect any local town codes?
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Brucey
Velcro Man
At least with my experience using mt solar design tool i played around and got something I liked the look of and then a couple days later I got an actual quote with all the specifics. The OPs design is going to have gigantic footers for those four posts but you don't have to "shore up" an MT solar design.
Price wise I'm guessing maybe $50k plus per array minus concrete?
Brucey
Velcro Man
Did you put 70mph as the wind load limit in the design tool?
Your local code authority will have a wind load design requirement that's what you need to input into the design tool. Chances are that limit will be 120mph+.
Quattrohead
Emperor Of Solar
You are going to end up paying more for mounting the panels than you are for the whole rest of your system, it's not financially practical what you are proposing.
Winter in your area is killing your solar proposal, I think you are better off hooking up to grid or relying on a massive amount of propane.
A far more manageable project would be a smaller system that can run your AC in the summer.
Winter in your area is killing your solar proposal, I think you are better off hooking up to grid or relying on a massive amount of propane.
A far more manageable project would be a smaller system that can run your AC in the summer.
OffGridForGood
Catch, make or grow everything you can.
He just needs to find an old Drive In Movie theater and buy the structure - heck maybe they pay him to take it away for them LOL
Zwy
Emperor Of Solar
4 feet clearance is enough when tilted enough because snow never settles on the panels. There isn't anything to really slide off. You don't need 85°, you need about 60° max. Higher height means you have to dig deeper for the pole foundations for not only ballast against uplift but also because the pole above ground is a lever. The 5 row tall array has 9.5 feet deep holes but I think 8.5 feet was enough according to the calculator. The reason for the extra foot was 8 inch pipe comes in 21 foot lengths and why cut off just a foot? Just dig the hole an extra foot deeper.
On MT Solar mounts, all panels will go in landscape pattern. The panel mounting rails run vertical. This is due to the frame of the mount.
An additional brace is really not needed if you go with 8 inch SCH80 poles. The tilt mechanism will break first, I showed the weak points in the video where the failure was. The tornado damaged mounts did have the SCH40 poles bend over however this was due to the adjusting screw and mount breaking which left the panels vertical, then hit with 150 mph winds. The MT Solar mounts are rated to 102 mph winds.
Zwy
Emperor Of Solar
Not needed, use larger diameter/thicker wall poles like 8 inch SCH80
Zwy
Emperor Of Solar
The shed to the right of the array is getting panels mounted above the doors next summer. The shop directly ahead of the back shed has the same door setup and it will get some vertical mounted panels above the doors at some point. These are for winter production mainly and use up extra panels in a pallet after putting up ground mounts.
I have seen full production from panels in winter due to albedo with snow cover on the ground. In months without snow, I don't get full production from the array. The biggest problem is cloudy weather in winter.
I don't know your fabrication skills but one can build the frames for the MT Solar mount easily enough. The I beam rails are shipped in sections due to shipping requirements but a single long piece will work and be easier to assemble.
The tilt axis is just 4 inch SCH80 pipe. Two pieces of rectangular tubing which can be welded and not bolted to the I beams. The pole mount and adjuster can be purchased from MT Solar in the parts section, I purchased 2 of the screw adjusters and need one more for next year. . Rails are easily sourced.
I considered building a mount myself but the used mounts were cheaper than what materials would have cost. I already had the pattern from the first mount so it isn't hard to copy.
Zwy
Emperor Of Solar
To add to that, the more poles, the more strength it has. MT Solar has single pole mounts so each pole could handle 5 rows high and 3 rows across with the older under 300W panels. With larger panels, rail length limits panel rows to 4 high. With 8 inch SCH80 poles, it would be 5 columns in width unless the panels are larger modules like the original array I put up that had 530W panels which are longer. MT did the calculations for that mount and it only has 6 inch SCH80 poles so it could be 5 columns wide per pole with 8 inch SCH80.
Zwy
Emperor Of Solar
MT Solar runs an engineering sign post application for determining all loads. You can print the whole report out, it is about 10 pages long.
Zwy
Emperor Of Solar
MT Solar are basically modular design. He would need about 2 of these mounts. Cost of $10K each comes to about $20K but freight won't be cheap. Then poles and cement, all rails and panel mounting hardware is included.
Zwy
Emperor Of Solar
Are you willing to drive to pick up the mounts instead of freight costs. Freight added 1/3 to the cost when I did the original array.
I drill my own holes with the post hole auger I have. You may have to rent or you can go to a rectangular hole using a mini excavator. If going 9.5 feet deep with about 36" round holes, concrete costs about $700/hole. 8 inch pipe SCH80 figure $1k per pole unless you are friends with a welding shop that uses volumes of steel. Figure $8K for a 4 pole mount to $10K for a 5 pole mount just for the foundation. Wiring from panels to SCC's is extra of course depending on what you are using.
With that length, I'd opt for 5 poles myself. Usually the mounts are poles on 15 foot centers with 7.5 foot I beam sections. More poles= more wind resistance and stability. Plus more adjusters. I see they have pole spacing at 19.75 feet, I'd prefer close to 15 feet myself.
OffGridForGood
Catch, make or grow everything you can.
"This mount fits on 2 – 8in Pipe Sch 40 inch steel pole(s) with a spacing of 19.75 feet (not included)."
from the link provided to MT they showed the cost of the standard mounts at 10K each - but indicated the posts are not included, and the foundation work will also be on top of this cost.
Can you build it - or will you need to hire out for the installation?
It will add up rather quickly for an array this size.
Zwy
Emperor Of Solar
That has already been discussed.
An array that size will cost money no matter what the mount used. There are some economies of scale though.
I'd put in a smaller tilting pole mount myself with about 1/4 to 1/3 more panels mounted vertically on a building side myself.
Zwy
Emperor Of Solar
For the size of system you are looking at, it won't be cheap.
One can stick it to the man one step at a time. Do a step each year. But plan ahead for the eventual total stick it to the man.
For me, the return on solar is better than what the money would fetch for interest in money market. Borrowing money to install solar adds to the cost and one might be better just using grid power.