DIY Solar Panel Rack

[mungewell]

Hi all,

I'm finally getting a solar system together and need to build a rack to hold the panels.

The panels are quite large (48"x42", 40lbs each) and I want to mount 2 side-by-side on a ground mounted rack, which would be adjustable for tilt.

One area of concern I have is the amount of wind we get (yes, a windmill is the next project), greater than 60 mph is not uncommon. I am worried about the panels catching the wind and breaking the mount.

My basic idea is a pair of 2x6's forming the sides of the rack, with aluminum angle run across the sides to hold the panel. The 2x6's would be further braced on the reverse with a diagonal piece of angle.

The tilt adjustment would be with concentric square tubing, with through bolts for making the adjustments. The four feet would be hinged with some large angle and J-bolted onto sono-tube concrete footings.

I thought about doing the whole lot in aluminum, however this would be quite expensive and the design would be more complicated to use the angle (lots more junctions needed).

With 2x6 I can cut a small grove to take the angle and bolt through the flat into the edge of the 2x6.

I'll attempt to attach as quick sketch of what I mean.... any comments?

Simon.

[TomW]

mungewell;

Not sure of the value of your panels but we have about $1400 worth in our array and there is just no way I would trust mounting them on a wooden frame. Commercial panels last 20 years and I doubt wood will last anywhere near that in ground contact. I wouldn't mount them to modern treated wood, either because there is a well known issue of corrosion of metals in contact with treated wood as made today.

I just cannot see the point of mounting expensive equipment on anything but steel that could be damaged by wind if it worked loose. Risking high priced equipment to save a few dollars just doesn't make sense to me. That said, I suspect there are lots of panels mounted to wooden frames. I just would not do it myself.

Just my opinion.

Cheers.

TomW

[Ponderance]

i would refrain from using wood of any kind and go out-right for C-purling in place of standard 2x6's... and as far as using square tubing... i would go for rectangular tubing instead say 1.5in x 3in 12ga anchored between pieces of C-purling sorta like this ]H[  the brackets represent the C-purling and the capital H represents the rectangular tubing ... use the idea you had with one size inside the other to adjust the angle of the solar panel rack...

[Phil Timmons]

I like using Unistrut (aka B-Line or Kindorf) for stuff like this.

(too much info at http://unistrut.com/)

You can get it at Homeless Depot or Lowes (or Graingers or just about any electrical supply house).  I call it an "Erector Set for Electricians."  It all bolts together, has brackets that allow it joint many ways, comes pre-painted or galvanized.  Means no welding and minimal cutting.

Since you are not using much, you may be able to get scrap pieces (full sticks come 10 feet or 20 feet) from a local electrical contractor.  I use the stuff to build everything -- especially prototypes and onezy - twozy things like you are building.  The fully adjustable slides make it easy to fix mistakes or change your mind.

[terramir]

I like your idea except for the wood. My two panels are mounted on an 100 Lb+ Steel plate and well there fixed right now. I plan on actually putting them on U-channel re-enforced fiberglass  when I have all four panels up and running. (Have one I got to fix and another one I already got the cells)as for your tilting idea I think it's great; however for me them rotating with the sun would make more sence, since I live in los angeles. Tilting may be a later project.

Good luck on your project.

terramir

[scottsAI]

Hello mungewell,

Not sure where you are, if snow is consideration, make sure the bottom of the rack is above highest snow level. Seems to be something people forget, then have to fix. Yours is very close to the mounting.

Drawing shows it on flat ground, make sure the foundation can resist the wind load. Including pulling it out.

If you can build this, then stepping it up to tracking is not much harder, for DIY tracking is generally worth it even down south. Further north the more benefit to tracking. One example, many out there:

http://www.solar-trackers.com/concentrator2.htm

You can always build it for tracking add electronics later to make it work.

Not with concentrator, requires tracking.

Tracking concentrator, you should be able to collect twice the power out of a set of panels without spending twice the money.

Have fun,

Scott.

[mungewell]

Well thank you everyone for your comments...

So wood is out, I'll have a look into aluminum channel or box for the sides. I am still  concerned about the wind, hence ruling out tracker - even though I know it would substanctially improve summer production, but not terribly significant increase in the winter.

I did some prediction on the angle/power relationship, in the form of a spreadsheet:

http://www.otherpower.com/images/scimages/2645/solar_panel.xls

We normally have some snow cover on ground, but not more than about a foot. Should be clear from the bottom of the panel (can always get the shovel out) and should reflect a little more light onto the panels.

I'll probably ask more questions later, but promise to post so pictures of the resultant rack.

Cheers,

Simon.