Wood frames

[lile001]

I've used treated wood to make solar water heater frames with some success. I used treated wood sleepers on the roof, covered them with aluminum flashing to keep the sun and some of the moisture out, and then used aluminum struts to support the panels at an angle. Hardware is all stainless steel fasteners, with some aluminum tubing and aluminum panel feet.

What do people think about such a system for solar electric panels? Pluses: treated wood is inexpensive and easy to work with. Covered with aluminum (I used prepainted aluminum fascia, then painted it to match the roof) it should have a long life.

I've got to build racks at a different angle than the roof, it's only a 4:12 (19 degrees) and I need more like 38 degrees or so. I'll probably make it adjustable, and use a steep angle in the winter, a shallow angle int he summer. Unirack doesn't seem to have a simple way to do much but mount flat. is this true?

What do people think of this idea? Nuts? Sound?

[Mike90250]

Why not use aluminum channel or extrusions? Wood, outdoors, is going to weather. The flashing trim will protect it some, but the problem is the mounts NEED to prevent the panels from being broken. The frames on a panel, are frames, they are not sturdy mounts, ready to use, they are not strong enough. Wood rails are not nearly as strong as metal.

[lile001]

Why not use aluminum channel or extrusions? Wood, outdoors, is going to weather. The flashing trim will protect it some, but the problem is the mounts NEED to prevent the panels from being broken. The frames on a panel, are frames, they are not sturdy mounts, ready to use, they are not strong enough. Wood rails are not nearly as strong as metal.

Seems like the ready made systems like Unirack are pretty expensive. If one was going to use metal, would square aluminum tubing work out cheaper, and just as effective? Unirack looks good if you need thier special mounting clamps, but if the solar panel comes with mounting holes, I would think any jack-leg could mount that to a rack made of square tubing. Is that what you'd do?

[lile001]

Seems like the ready made systems like Unirack are pretty expensive. If one was going to use metal, would square aluminum tubing work out cheaper, and just as effective? Unirack looks good if you need thier special mounting clamps, but if the solar panel comes with mounting holes, I would think any jack-leg could mount that to a rack made of square tubing. Is that what you'd do?

A few prices: Airparts (a supplier I use) advertises 1.25" square aluminum tubing for $4 a foot. Unirac, the one place I checked, goes for $6 a foot. At these prices, I'll have $2000 - $3000 invested in a rack for the system I am thinking about. I'm using Kaneka panels, I think, which are low efficiency, so the rack gets bigger and more expensive. Hidden costs......

Although I don't want to use a flat-to-roof configuration since my roof is only 4:12, I can see the installation advantages in cost and simplicity.

[Chris @ EcoFasten Solar]

Flat to roof is going to be simplest installation, no question there. I'm curious, have you priced out some generic strut channel? It's like erector set for big kids so you can arrange it to provide the tilt you need, and it is in most cases more economical than the purpose-made mounts. A quick google for strut channel gave me prices on the order of ~$3.50/foot, although that will vary depending on the specs you require.
(full disclosure here: I work for a company that sells roof mounts)
What are you using to attach to the structure?

[lile001]

Unistrut (or approved equal)

Flat to roof is going to be simplest installation, no question there. I'm curious, have you priced out some generic strut channel? It's like erector set for big kids so you can arrange it to provide the tilt you need, and it is in most cases more economical than the purpose-made mounts. A quick google for strut channel gave me prices on the order of ~$3.50/foot, although that will vary depending on the specs you require.
(full disclosure here: I work for a company that sells roof mounts)
What are you using to attach to the structure?

Local metal supplier lists these prices for aluminum tubing:

1.25" square aluminum tubing $2.75/ft
1" square aluminum tubing $1.60/ft

I haven't checked on Unistrut yet. I'm trying to stay away from galvanized stuff on the roof, it eventually becomes un-galvanized. I know unistrut comes in Fiberglass, I wonder if it comes in Aluminum as well? Probably, it's industrial stuff.

[Mike90250]

Fiberglass will not take more than 5 of UV. Look at boats, they are needing new gel coat after a couple years. Aluminum is good, if you can get it Anodized. (clear or colors)

[mountain]

fiberglass unistrut

As an industrial electrician, I have used miles of this stuff. Very versatile & available world-wide from any electrical wholesaler. It is easy to work with, although you must wear a mask when cutting it (the fiberglass). Most of the metal stuff is recycled mystery-metal, so out-doors we always paint it, otherwise it may rust, depending on what got dumped into the grinder that day.

http://www.unistrut.com/site_map.php

scroll down to the fiberglass section.

also

http://struttech.com/?gclid=CNqawMHniaACFQ1N5QodyBzCfA

On providing UV protection for fiberglass, you are certainly allowed to paint it with a compatible rosin-coat. Black is usually UV stable.

[lile001]

Grounding nixes wood frames

Here's why you don't want to use wood frames or supports: Grounding. An AEE lay-in ground clip, one per panel, is required by code if they are not mounted on aluminum rails. clips are $5 a pop. $5 will pay for 2 feet of rail, or almost enough to mount the panel. If you use aluminum rail, then you need one ground clip per rail, instead of one per panel. The cost of the grounding clips adds up fast, plus extra wire.