how to fix panels to a unistrut support frame

[Ivan]

Paul, 

Before you go and order some stainless sections (I couldn't find any when I was looking), reconsider aluminium - try drilling a hole in your stainless solar panel frame - you'll soon change your mind. It's horrible stuff to drill holes through. The professional roof-mounting systems are made from ally sections, not stainless. I think the aluminium sections are lacquered to prevent surface corrosion - like aluminium window frames (possible source of aluminium section). I used a couple of aluminium back rails for some shelving to mount 2x60W panels on my garage roof - works well, and has not shown any sign of corrosion having been attached for around 2 years.

Ivan

[martin]

the aluminium angle that I used was obtained in Focus  - around £8 for an 8ft length!
ps the wooden pads are tanalised timber, I nicked some roof battening off my partner-in-crime!

[Ivan]

I think the angle you buy in shops will be lacquered as standard - they don't want to be selling anything unless it's nice and shiny. Martin, how long has it been installed? If you 've had a few months of rain on it and it doesn't show any corrosion, then it is probably lacqured.

[martin]

been up about 6 months, no sign of corrosion!

[SteveH]

 Just had a look in an old RS catalouge & Stainless Steel angle is avalible... as a guide 1½ x 1½ x 1/8" was £20 per meter in 2005...

 I wouldn't recomend RS because they are expensive... but if you were happy to settle for 304 (A2) grade you could try approaching a dairy equipment supplier...

[Paulh_Boats]

Martin,

Thanks for the pics. Thats what I'm gonna do ... just need to get myself in Everest climbing mode. If the weather is rubbish I might just bottle out and stick them between wall and conservatory at a high angle to catch the winter sun. Will still get sun 2 hours before/after midday I think.

Yes Ivan - I have drilled one of your wonderful stainless frames, 25ft up on the roof with a cordless drill! As they say on TV "don't try this at home". Tremendous skill with cobalt tipped drills eventually got me a 8mm hole but it was hard work.

There is zero problem with exposed aluminium, except perhaps exposed coastal locations. In the air Aluminium oxidises to Aluminium Oxide which forms a tough protection layer that prevents further oxidation. So when the laquer wears away the aluminium will loose its shine but then be protected.

SteveH, thanks for the RS tip. No wonder cows look worried, what do they use the angle sections for? 

-Paul

[SteveH]

 Paul

 A couple of things to watch-out for with the Aluminium frames... Avoid direct contact to steel fixings or electrolitic action will take place & the alluminium will get eaten away... Same principle as the blocks of alluminium that get strapped to oil rigs as sacrifical Anodes (Or is it Cathodes)... You may get a similar problem if the frame is earthed via the pipe work too...

 The dairy equipment guys use Stainless angle to make wall brackets to hang...... dairy equipment... Strange but true... The cows only get to look on....

 Drilling Stainless is more difficult than a lot of metals but not too difficult... Pilot drill the hole with a small drill first & use coolant (Water or oil... Parafin works well too) to remove the heat as stainless tends not to transfer it away very well... I just use HSS drills...

[Ivan]

I spoke to an experienced solar installer last week - he showed me some professional solar mounting systems that he distributes, and then told me that the best thing to use is unistrut. Says it all!

Ivan

[tony.]

guys, incase your still looking, you do get stainless steel unistrut.

tony

[StBarnabas]

Interesting thread. As you may know I too am hoping to install a roof mounted PV array this spring and mounting is my major concern. Please keep the pic's up. Will let you know how I get on and hopefully will a Amaterasu like pictorial of my Navtron PV system. (Shame Amaterasu no longer seems to post on the Forum).
Sean

[Paulh_Boats]

Sean,

I have some unistrut frames and fittings, but so far no time to move the panels from the conservatory roof up onto the house roof.

-Paul

[StBarnabas]

Possibly Unistrut is the way to go. Just realised how old some of the posts are! I like the idea of stainless and have downloaded the unistrut catalogue.

Paul if you get around to doing your's before I start mine please provide pic's. 

Ivan any update as to when your 110Wp panels are likely to be back in stock?

Sean

[Ivan]

The problem with Unistrut is the weight (otherwise, it's ideal, and even their galvanised product has a long guarantee against corrosion). If you're putting a big array (1kW or more) on a roof, you're putting up a fair weight of panels. Use a steel mounting structure, and you're putting up twice as much, and often more than the safe carrying load of the roof - hence my preference for aluminium over stainless or galvanised steel.

St.B, I've really no idea. Best thing would be to give the office a call. I think it is probably imminent.

[StBarnabas]

Ivan
thanks. The office promised to contact me when it  arrived in. Things are a bit hectic at the moment so it will be a good month I suspect before I get all the pieces in place. I havn't given roof loading that much thought. It seems very over-engineered compared to modern buildings - possibly not surprising for an early 19th centuary church. Though aluminimum may have advantages from a corrosion point of view. Unistrut don't seem to use Aluminium however.
 
Sean

[Joules]

Guys,
       I've been working on a solar PV mounting frame for a few weeks now, it's all stainless steel and the mountings come through the roof to an internal support system and the load is spread over many roof trusses.



The frame and brackets are all made from 30 x 30 x 3mm stainless angle.  It will be carrying x6 130w panels.  The panels in a prefabricated 3 stack can be bolted onto the horizontal frames.

                                          Joules