What to attach anchor to

[bisquits]

I'm planning on installing panels on my roof soon. I installed panels on a metal shed last year with no problems, but the house roof has recently been slated and looks like this. When I've researched what to install the brackets to that hold the rails that the panels will clamp onto (e.g., these guys), people seem to attach such brackets to the vertical purlins of the roof, which are visible/accessible (like in this video). But my roof has felt over purlins and batten then over the felt, which the slates are attached to. Would the battens be strong enough to attach the brackets for the rails? Or do I need to hunt for the purlins and drill through the felt and risk water ingress??

Edited March 27 by bisquits
update link

[Dillsue]

You don't need to hunt for the rafters as there will be screws/nails in the battens which hold the batten onto the rafters. These will show you the position of the rafters for you to fit the roof hooks.

 

I'd check your battens and slates have been fitted correctly as there's usually space between the top of the felt and underside of the battens to allow ventilation/water run off. Im no roofer but AFAIK the felt usually sags between rafters to form this space or if there's boards below the felt, counter battens are used. If that needs changing get it done before you fit the panels and get the roof hooks fitted while the slates are being laid.

[haythorn_1]

I just did this earlier in the week. It’s quite easy to find the rafters as Dillsue says. Plus you can feel them through the felt.

[Russell griffiths]

@bisquits to get your terminology right, you are looking to screw into RAFTERS these are the timbers that run from the gutter area, to the ridge area, PURLINS are the huge beams that run left to right under the rafters to add additional support to the rafters. 

[BotusBuild]

You've all got it wrong. You attach an anchor to the seabed

[Nickfromwales]

As said above, look for the fixings of the battens and there’s your fix point   Shame these didn’t go in roof, but there’s still an opportunity to do that and lose the slates if you’ll accept that? 
 

Anchor is a butter that goes on crumpets, immediately prior to applying grated cheese and then grilling.

 

@bisquits this type of thing goes on a lot here. lol.