I had two MCS accredited installers to survey and quote for mounting PV panels on a slated roof.

The first would drill holes through the slates, fix brackets to the rafters and fit rails to the brackets. The holes in the slates would be covered with a small piece of lead. The fixings would leak, the slates would be cracked or broken, it would be impossible to fix the brackets securely without breaking slates and the array would rattle in a wind. The second is more conscious of the fact that a roof is designed to keep water out but both had no method to use to decide how many fixings were necessary. The site is very exposed.
When the panels are fittted the fixings are invisible and difficult to repair.

I searched the net for an approved system for use on slate roofs but found none.
I spoke to Building Control, pointing out that PV panels could blow off and be very dangerous, that the integrity of slate roofs was damaged by drilling holes in slates. I asked if there was a BBA accredited system. While they understood the problem they could not advise me.

Fitting PV panels to a slated roof could be a disaster, the roof could be ruined, the panels could come off and injure someone. It could cost more than the system was worth to repair the roof.
Is there a BBA accredited system for mounting to slates?

I have designed a bracket and flashings which will not leak but how many fixings per area of panel are required and how strong do they have to be? Could I use my brackets without BBA? Who knows?

As far as I know you can use any fixing method you choose, but it has to be strong enough to resist wind uplift (I may be wrong,but I can't find anything online about specific regulations.) personally, I use the Hilti range, which are excellent. you strip the slates off and attach with coach bolts to the rafter and then slate around them in the same way as any penetration, using a lead flashing if required. It's a great system - extremely strong and versatile and if you are a competent slater it won't leak.

There are a number of brackets which sit on top of the slate and bolt through it, which I think is just asking for trouble - much higher stresses on the fixings, increased load on the slate, which will break. Guaranteed to fail and leak in my opinion.

Stripping back, firm fixing, reslate and flash is longer and therefore more expensive and requires a higher level of skill. But it's the right way, which as far as I'm concerned is the only way. I'd be interested in seeing your idea tho..

regarding fixings distances , panel manifacturers give guidance depending on the product used.

is that flashband?

Posted By: evan
Drilling through the slate works perfectly well.

It sounds straightforward enough evan and in careful hands possibly OK. My concern would be the odd less than carful fitter who overtightened and then wind loading could easily stress and crack the slate. I guess the square of lead you mention would have to be the same size as the slate underneath.

that way sounds grand, but most installers I've come across are just drilling the slates and screwing straight into the rafter, so there are stresses all over the place... any idea what the publication is called?

it sounds super useful - I'm struggling to find any new 'best practice' material - I'm going to write my own one up for my company as part of my training manual and QMS. I come from a roofing background, so it's a bit worrying seeing alot of the installs carried out by sparks with limited roof knowledge. I've seen some shockers!

yup. The thing I've been wondering about is insurance - I bet a pv array will not be covered under regular home insurance - does anybody have any idea about custom pv insurance for householders? I want to be able to recommend this to my clients..

I just checked with direct line, and apparently it is covered, so I would presume that most other insurance houses do cover it too. They recommend notifying them about the install, but it's not a requirement. who knew?

Jolly good.

On the question of insurance.

So far insurers do cover the panels as a standard risk.

However, I heard that there had been an increase in theft of panels on low roof installations in Germany and that installations there now have anti theft devices as standard. Schletter, a company like Shuco who manufacture roof mounting frames, do such an item.

Fitting frames to a slate roof is probably easier with the batten mounted fixings, especially those that have several screw holes and can therefore be sited correctly.

Roof hooks can let water in if they are too thick and cause the tile to lift, from below when there is heavy wind and rain. Is Rosco 82's tile lifting in the photo?

It looks like flashband, which is kind of bitumen backed fake lead effort. not a fan personally.

Posted By: squowsethey'll still get their money

And if they have any business sense they will have two companies, one installing and one collecting the revenue. Bet I know which one will go bankrupt and dump the liability, can't be long with the undercutting that the PV installers are doing to each other that the birds will come home to roost, well to a wet home anyway.
Anyone know of any installers that have gone under already?

One of the big fixings companies make a range of fixings that carry loads onto the rafters without impairing the integrity of the roofing materials.

As a slater of 40+ years, I now develop solutions to problems encountered in my job for many many years. I exhibited a product (the Hallhook - used to secure slipped slates) at Ecobuild 2011. It was at the show I was approached by the Director of Sustainable Housing for a large corporation, and told about the very problem being discussed here; flashing around solar panel brackets on slate roofs. I have to say, upon spending the next 6 months developing a solution, I very nearly threw in the towel. I was so shocked and angry to see the practices taking place on slate roofs. I encountered so many 'roofers' who didn't have the first clue about slating. At least PV installers admit to not knowing what they're doing - it's not their fault - I'm the first to admit I can't put batteries in a torch - which is why I don't go near electrics! To see first hand the mess being made of a slate roof is personally very difficult, and whilst advising some of the large installation corporations (British Gas, Mitie, etc.) it became apparent to me that it isn't actually the fault of the installer, it is a specific task which needs a solution which is fit for purpose. The problem actually goes deeper than this; the bracket manufacturers are making brackets which are not fundamentally conducive with the concept of a weather tight flashing repair. Anyway, I approached BBA, NHBC, NFRC - there is no regulation/standard. It really is a case of HOMEOWNER BEWARE!. I recently worked with MCS, who now have a draft standard due out in the next 12-18 mths which covers the weathertightness issue. It will take time, but regulation is on its way. I developed a solution and have sold in excess of 10,000 SolarFlash systems since Oct 2011 to PV installers, and we are now moving to distribution as a route to market. Please see the website for all details www.hallclip.co.uk. Rgds, Jimmy.

Okay thanks - new to this - didn't mean to break the rules, just a very personal issue for me

Rgds, Jimmy