PV Panel Mounting Question

[Windpower]

Looks like the chest freezer has seen better days....

I am starting to plan the racks for the solar panels --- may I ask for some engineering advice ?

I think 3" water pipe set in concrete should work for the uprights -- probably 9 panels per rack

your thoughts ....

[MountainDon]

There should be info available from any one of the manufacturers of pole mounts. I used Unirac and at the time they had an instruction manual/shhet for the installation of just the pole. They had a pole diameter slector for different amounts of sq ft being mounted. Wind loads, panel sq ft, pole ht. above ground all played a part. They had charts that also spec'd the amount of concrete as well as pole depth.

Try a Google for something on that; probably better than a guess.


FWIW, my three panels spec'd a 4 inch schedule 40 steel pole, (old drill pipe)  something like 4 to 4  1/2 ft in ground and about 7 cu ft of concrete IIRC

[MountainDon]

Look at this

Use the selection guide to determine their suggested rack and then the link above to see pole size and depth

[Windpower]

Thanks, Don

I should have been more specific

I am trying to 'home brew' (trying to save some money ) something on this order -- maybe have 4 tilt positions -- or just fixed for now

[MountainDon]

I saw "pipe" and "concrete" in context with "PV panel" and my brain went....  "pole mount"     

In that case, Never mind what I said.   

How high would the top edge of the highest panel in the array be? Six foot with a 90 mph wind agaibst the face can generate 13 lbs PSF.

The handiest part about those factory made bars are the slots and the hardware that slips into place making it possible to mount without having to drill holes.


I made a bunch of holes in the bar that holds the angle; one for every pair of months. I have ended up using the most tilt and the least tilt. And have found that leaving the rack in the winter use position does fine all year. Maybe this year when I switch to winter I'll end up leaving it there. YMMV.

[UK4X4]

Slotted strut for adjustable fixings galvanised adult mechano sets- use the 1 5/8"x 1 5/8"

http://www.mscdirect.com/browse/Framing-Channels-Struts?navid=12104779&searchterm=strut

sprung loaded nuts
http://www.mscdirect.com/product/54055132?fromRR=Y

bases

http://www.mscdirect.com/product/54055546?fromRR=Y

Easy peasy !

Oh but don't order galvy bolts as they don't fit the galvy nuts! get stainless or zinc plated

[Dave Sparks]

Linear Axis Tracker




This idea will not save money unless you need to add longer useable hours of maximum power. I am just finishing this horizontal linear tracker. It is about 50 feet long and will have 4,320 watts. It has a power gain of 25% above the rated for grid tie  For offgrid it is really the hours of full power that we can use that is the key. Running a heat pump or deep well during the last or first hour of sunlight for instance. This tracks 45 degrees both ways from horizontal. It is kind of the best of a single axis and dual axis design, with half of the cost.

The hill in the picture is near Glens home. Hey Don! I wish we could have seen you this summer. The trip to NM fell apart when the client got divorced.


48 volt battery bank

[MountainDon]

Hey Don! I wish we could have seen you this summer. The trip to NM fell apart when the client got divorced.

Too bad it didn't work out. I was looking forward to it!

More info on that array tracker mount would satisfy my curiosity   

[Dave Sparks]

The second one on the page is the Horizontal row tracker. Really easy to install  (except on hills like in my picture) and excellent for high winds.

//http://arraytechinc.com/residential-trackers

[Native_NM]

I saw one up off road 103 that was mounted on PT wood frames. 

Looked pretty nice. 

[Dave Sparks]

I saw one up off road 103 that was mounted on PT wood frames. 

Looked pretty nice.

Agree wood is a wonderful mount and easy if you use the slotted aluminum extrusion rails for the panels. I have sometimes just staggered the ground mounts to get the long hours of sun like a tracker.  In my opinion adjusting the vertical angle is really a waste of time offgrid.

The Azimuth angle,
well you have to account for it in a full time offgrid home that needs conditioned space in summer. Gardeners/Ranchers that need a lot of water are another reason to harvest sunlight in that 250 degree summer sun path.





I really like this one. These are the Sanyo HIP panels (see thru). They are almost art. Panasonic bought them. They are the most power per square foot available unless you buy aerospace panels.

[MountainDon]

Nice battery bank there Dave!

[Dave Sparks]

Nice battery bank there Dave!

Thanks Don,  it was a hard decision for the owner. These are 2V cells that have three watering openings per 2V battery. The Surrettes have only one watering point per battery but have had quality control and manufacturing issues lately for this L16 model. There is also a US battery that is 2V and is similar to the Trojan. A little bit more maintenance but hopefully more piece of mind.

[MountainDon]

These are 2V cells that have three watering openings per 2V battery.

  That explains it! I was trying to figure that out for 48 volts. I knew they looked like L-16's but forgot they made a 2 volt type.      I thought one of us was nuts!

[Dave Sparks]

Well you were right! I know about my sanity and it is not always bankable! I am happy though.....Did my edit a few back work?

[MountainDon]

Did my edit a few back work?

No, but I made it work.  I truly don't understand linking from Picasa. I just muddled and did something right.

[PorkChopsMmm]

I know this isn't a pole mount -- but I think what you are describing sounds strong enough. For us Northern folks I would strongly recommend vertical adjustment -- we have high sun in the summer and extremely low sun in the winter -- plus we need the ability to shed snow.

Here is my pole mount I built this summer. I built it specifically to tilt to an extreme angle so that I wouldn't have to brush snow off of the panels every day.

[MountainDon]

Looks like a good size concrete anchor too.   

I like pole mounts in snow country, over ground mounts.

[Squirl]

Looks like a pole mount

Here is an article on DIY pole mounts.

http://www.homepower.com/view/?file=HP108_pg28_Schwartz&pdf=1

With the cheaper price of panels, dual axis tracking is not usually cost effective.  In far northern latitudes a 20-30% gain in power when you only have 1.5 sun hours in the winter might be the difference of keeping the lights on with single axis tracking. 

I like the home power site.  Typing in pole mount or ground mount into the search yields dozens of articles.  They have some pretty good pictures to follow too.  I saw one on there that was like the picture windpower posted, but hinged with C channel and a bolt for seasonal adjustment.  Pole mounts are more expensive than ground mounts.  I'm currently debating that myself.

Thanks for the picture porkchopsmmm.

[Squirl]

Porkchopsmmm, do you mind if I ask the sizing on all the hardware (pipe, box steel, panels)?

[Windpower]

Thanks for the home power link, Squirl

[Squirl]

http://www.homepower.com/articles/solar-electricity/design-installation/ground-mounts-pv-arrays

Picture 4 in this article looks like what you were trying to build.  I'm looking into that one too.