Friday, July 15, 2011

The Big Build (Part 1)

It was about time...  About time I got these solar panels up on the roof, where they belonged.

So began two weeks of major bodgery on the house roof.

I'd started collecting materials for the project a few weeks ago.  Proper solar cable - 50m of 6mmsq.  MC4 plug sets from a Chinese maker called Lensun sold widely on eBay.

I'd also done some research into mounting kit.  Peter, a friend from across town, had mounted some 100W and 185W panels using glavanised steel 41mm cable conduit and spring channel nuts.

I ordered some of the same rail but it was out of stock.  They'd also stopped selling the right spring nuts to go in the channels so I ordered these from another company.  The nuts turned up quickly enough but only half of them were galvanised!  A call the supplier sorted this out and they sent me a whole load more at no extra charge.

After 5 days of waiting for the rails to turn up, the electrical supplier admitted they weren't stocking them any more.  Useless.  Now I had two loads of channel nuts for non-existent rails... Back to the drawing board.

Peter had recommended a PV installers supply shop on the web (  They specialise in low cost aluminium rails and clamps and the roof brackets.  Not as complicated an aluminium profile as some makes, but cheap and it does the job.  The rails come in 3m lengths with U bar joiners to make longer rails.  I ordered 8 rails to make the two rows of modules to go on the roof (one a bit shorter than the other as their is a sewer vent chimney sticking out of the roof at the bottom corner).

They also sold the matching Hilti stainless steel channel nuts for these rails. 
Unfortunately, this supplier also screwed up and sent me a box of wrong stainless steel bolts instead of the roof joist screws for the roof hooks, but a phone call had the right screws delivered the next day at no extra cost.

One thing that made this install more expensive was the fact that all my PV modules are different heights, ranging from 30mm to 50mm tall.  This meant buying different sized end clamps to match and installing the modules in blocks that were the same height.  Luckily, they sell "universal" in-between clamps that are shorter than 30mm deep to allow them to hold down any sized PV module.

Now all I needed was some scaffold or an access tower to get up to the roof...  And a head for heights!

Renting scaffold turned out to cost a fortune (especially if you didn't know how long you would need it for).  In theory, you'd only need it for a couple of days to do a solar install, but when did any of your DIY ever go to plan?

Then I found the answer... It was cheaper to buy an access tower than to rent one!  These guys at sell a well made DIY 7m tower kit that flat packs for storage.  It came with big outrigger legs to keep the tower steady even when me and Peter were up at the top.  In the end it was a good buy as I used it for over two weeks, making it break even compared to renting a tower.  If I use it again, it will have saved me money.

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