Replies

1. Expert Member
   Akos | Nov 03, 2024 12:40pm | #1

   All the commercial flat roof solar installs I've worked with had ballasted mounts. I don't see why these wouldn't work on a residential roof. I would not go for anything that puts screws through the membrane. Search for "ballasted flat roof solar rack system". They generally keep the panels at a lower slope which reduces winter production a bit but doesn't change the yearly production all that much.

   Another option, if you have parapets, is to clear span with steel structure above the membrane and install racking on-top of this.

2. Expert Member
   BILL WICHERS | Nov 04, 2024 08:50am | #2

   My preference is to have the structure incorporate some "hard points" that a seperate structure can be secured to to support the solar panels above the roof. I do the same thing if there are any antennas going on the roof. All the "hard points" are are rigid extensions up from the building structure through the roof that provide a secure attachment point for a support structure for the solar panels, and that support structure can be a purpose-built product, or can be site built from a support system like steel strut. This avoids the need for the solar installers to put in any new roof penetrations, all of which are potential failure/leak points for the roof. With the hard points pre-installed, the roofers can flash and seal all the structural attachment points before the solar installers show up on the site.

   It's easy to put in hard points made of steel pipe if you use the usual roof "boots" used for things like vent pipes and electrical conduits. It's also possible to extend wood pieces up. Do whatever works best in your application.

   I'm not a fan of ballasted mounts for two reasons: 1- they often aren't sufficiently ballasted (not all concrete blocks installed, hollow instead of solid blocks used, etc.), which leads to 2- stuff can blow off the roof during high winds and cause damage. Many commerical buildings will no longer permit the use of ballasted mounts because of problems with them getting blown off of roofs and damaging cars in the parking lots. It's safer to have secure structural mounts that won't move or lift.

   Bill

3. 
   badmechanic | Nov 04, 2024 05:04pm | #3

   This product looks similar in design to the pipe-format "hard points" Bill suggests. https://www.ironridge.com/component/qbase-low-slope-mount/

   The installer drills through the insulation (2" hole or so). The hardware is fastened to the rafter or sheathing. Insulation is then added. Flashing is then added for the protruding cylinder.

   One potential problem with this is the pipe boots I've seen add a fair amount of height. IronRidge recommends using "chemlink ecurb," which seems to add only 3" of height and is probably acceptable to us.

   
4. Expert Member
   Akos | Nov 04, 2024 08:03pm | #4

   I'm going to disagree with Bill here.

   For a resi roof, you want as few holes through your roof membrane as you can get away with. Even when well done, each is a potential leak point. Keeping a flat roof leak free in the long run is hard enough already, don't complicate your life.

   If you are in tornado alley, by all means mount onto your parapets, even there I would not mount to the roof deck. Elsewhere go for ballasted. If you don't like ballasted, design a car port and put the panels over it.

   Flat roofs are pretty common around me and they often have decks on top. These just sit over the membrane, only thing keeping it on is gravity. Since I've seen 30 year old ones, they definitely don't go flying off. Properly designed and installed ballasted setup is no different.

5. 
   hujun1 | Nov 04, 2024 08:09pm | #5

   如果您身处龙卷风走廊，请务必将太阳能板安装在护墙上，即使在那里，我也不会将其安装在屋顶甲板上。其他地方可以选择压载太阳能板。如果您不喜欢压载太阳能板，可以设计一个车库，然后将太阳能板安装在车库上方。