Solar Limpets

[dansk]

Im going to use these on upcoming job - they only sell in box's of 25, any one got a few spare they wanna sell? i need 34 in total.

 

[SolarCity]

Let us know what you make of them. They look pukka in my opinion.

 

[dansk]

agreed, its a rosemary job, and they no more expensive than the Renusol hooks i buy, plus the saving in lead.

 

[SolarCity]

Looks like a quicker install too.

 

[dansk]

yep, i dont see any downside ATM.

 

[Worcester]

We're going to use these on a 9.5kw Plain/Rosemary tile install next week, so we'll take a few photos, -

Carl from Solar Limpets came out and cheked the roof over as these tiles are 11 x 7 not the usual 10 x 6 and he wanted to be sure that they'd fit OK, actually they fitted very well. He also offers free training, so he's coming out to get my tile roofing team trained up on the job. Can't really ask for better support than that!

@Dansk we may have a few over - bought 125 of them as we'll space them at 800 not 1200, As always we'll double up in the corner (400 spacing) and then stagger the fxings so that with 2 rows of panels there will be be 2 fixings on every rafter. (Guess it's the engineer in me to spread the load as much as possible )

 

[dansk]

Thanks Worcester that would be useful - this job of mines on 400 centres - only wish i was doing a 9.5kw - this is a baby 2.75!

 

[Worcester]

@Dansk your welcome

 

[LightGEN]

Looks OK for Rosemary tiles but i don't like their approach to dealing with slates - drilling is a no-no.

 

[Worcester]

It's quite an intersting discussion on slate - it's currently going through MCS012 for slate - the point is how it fits, where the loads are transferred to, how any holes are sealed. It is a lot better than a hanger bolt which has a movement / bending action / stress points around the hole. I am reserving judgement on slate at the moment. However as an engineer having been involde in constructionm for >30 years, i can see all the arguments. hence judgement reserved..

 

[Gavin A]

It's quite an intersting discussion on slate - it's currently going through MCS012 for slate - the point is how it fits, where the loads are transferred to, how any holes are sealed. It is a lot better than a hanger bolt which has a movement / bending action / stress points around the hole. I am reserving judgement on slate at the moment. However as an engineer having been involde in constructionm for >30 years, i can see all the arguments. hence judgement reserved..

I'm not sure I really want to get involved in this, but what "movement / bending action / stress points around the hole" are you referring to with a hanger bolt, and why do you see this as problematic?*

We've tried all methods (other than these limpets) and firmly believe that hanger bolts are by far the best mounting method for slate when installed by a skilled, trained team who understands how to do it properly.

I really don't understand why everyone on here is so obsessed with a method that involves ripping out 1/4 of the roof slates, cutting big holes in them and then relying on flashing over the top to water proof the roof.


*eta - or more to the point, what problems that can't be resolved simply by drilling the slates with a slightly bigger hole than the bolt, and ensuring the flexible sealing gasket isn't over-compressed. IME the actual flex on these bolts is minimal anyway, certainly a lot less so than brackets.

 

[ktech]

I am starting to agree with you Gavin, although we have not used it hanger bolts do sound like a good solution for slate. If a hanger bolt works for sheet fibre cement sheets why would it be a problem for slate? Very interested in the limpets though.

 

[ktech]

Just to add to previous: If it's a cheap chinese slate then we don't touch it anyway as it falls to bits. But a good quality thick Welsh slate is a different story.

 

[Worcester]

@Gavin A, you should watch the video of a hanger bolt when doing the wind and snow loading tests on any roof material. I've witnessed many tests of materials, loadings and fixings in test labs that accurately represent real world conditions, and it's scary what happens to the whole lot (they test them to failure)

I also concurr that unless you use a professional slate roofer, rippingout a bunch of slates to put a hook in isn't a good idea, a good slate roofer should end up with minimal disruption to the roof structure, it takes a lot longer though than any other method, also therir are very few hooks that are properly designed for UK slate roofs, you've got to hunt out those ones that do work properly, then trial them, test them, and get experience BEFORE you start on a real roof.

Ends hijacked discussion on hanger bolts, this thread is about Limpets. For hanger bolts see the lengthy discussions and numerous threads on slate fixings.

 

[Gavin A]

I am starting to agree with you Gavin, although we have not used it hanger bolts do sound like a good solution for slate. If a hanger bolt works for sheet fibre cement sheets why would it be a problem for slate? Very interested in the limpets though.

I'd think we've installed in the region of 30 systems on slate, yorkshire stone, cotswold slate, and fake slate roofs, as well as metal, and fibre cement. That's probably getting on for 1000 bolts installed, with zero reports of any problems related to the bolts, and no evidence of any problems at the few we have had call backs for for other issues.

We did have one scare with a 10kW installation involving about 100 bolts, when the building owner reported a leak a few days later. We put a hose on it on full blast for about 2 hours and couldn't replicate a leak at all. We eventually tracked the leak to the ridge that had worked its way loose when we were working on the roof. We've also tested another installation on a rough cotswold slate roof with a hose for a fair length of time as well, which also didn't show any problems up.

IMO the only reason these aren't rated for this purpose by the manufacturer is that whether or not it's water proof is largely down to whether the installer is a knows what they're doing or not. You do need to be careful with it, flash any that are close to the gap between slates or that give any other cause for concern, and obviously pre drill pilot holes through the centre of the rafters, but done right and I really don't see why anyone would have a problem with it.

 

[Gavin A]

@Gavin A, you should watch the video of a hanger bolt when doing the wind and snow loading tests on any roof material. I've witnessed many tests of materials, loadings and fixings in test labs that accurately represent real world conditions, and it's scary what happens to the whole lot (they test them to failure)

I'd be interested to see that video if you have a link.

I'd be surprised though if any wind or snow loading on any individual bolt is worse than our installers using them to stand on while working on the roof.

 

[ktech]

I'm purchasing solar limpts for two jobs. One is going in next week. So will report back on how it goes. Service from the supplier seems excellent. They have offered to come to the first job and show us how it's done. At no charge! So I guess they have confidence in the product.

 

[Worcester]

Just finished the 10kWp job, limpets went in fine, overall much less hassle than cutting, grinding tiles, and like the fact that no gaps at all left at the end. We used K2 medium rail (have more than a few lengths in stock from our more usual type of commercial installs) so we set the brackets at 400 / 800 on the bottom rail corners of each row and then spaced at 1200. Also staggered the brackets to get an even rafter loading. Would definately use then again.

P.S. because we spaced at 1200 and had budgeted for 800 we've got about 45 or so left over so if anyone needs an odd number (they sell in boxes of 25 we're happy to split) drop me a pm.

Also we put an extra row in at the bottom which we later removed to to act as the first staging point for putting the first row of rails in. It didn't tkae a lot longer and definately saved a lot of broken tiles (these were a weird 11" x 7" size) so by not breacking many, and taking out for spares more that 80, we were also able to replace all the existing broken tiles (there were quite a lot before we started) the customer also has a pile of spares for other parts of the roof.

Carl from Solar Limpets came out and spent an hour or so going through the best way to insatll them and passed over a few tips to make life easier, by the time he'd left they'd put in the brackets for the equivalent of a normal 4kw install!
One neat idea was to use an additional limpet for the cable entry.
(We replace any broken tiles as they place the panels just in case any others get broken during that process)

 

[The Solar King]

I am looking at these as well. Karl kindly sent me a sample so my roofer can have a look. Like Worcester, I am maybe a little uncomfortable over the slate mounting, but went to look at a job today that would be ideally suited to this route. Slate roofs in Scotland are a nightmare as the slates are nailed directly to the close boarding (sarking) with no battens. You can easily end up using several hundred pounds worth of lead for soakers and flashing on a 4kW install. The alternative is hanger bolts through a lead flashing sealed up with lead mate or some form of roof integration. None of this is cheap so the method suggested by Solar Limpets is very seductive.

I understand from Carl the product is undergoing full BBA approval, which is beyond that required by MCS012. If they approve the product for use in this manner on slate I will be a happy bunny as life will get a whole lot easier.

Interested to know what others think.

 

[SolarCity]

Gordon, that looks great.

I will probably wait until the BBA approval comes. If that comes then I'll be giving them a blast.