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Recommendations for adjustable roof mount systems

Alegria

New Member
Joined
Aug 27, 2024
Messages
13
Location
Durango, CO
Hi, I'm getting ready to install six 645w Canadian bifacial panels on the roof of my tiny house and would really like to mount them at an angle. My roof is pro panel metal, south facing, and measures 24 x 8.5 feet, which fits 6 panels in portrait (93.9" x 51.3" ea) with a 10-inch overhang on either short-edge. I'd love to have the option for 15/30/45 deg angles, assuming it can be done safely, otherwise I'll opt for a permanent 30 deg angle. The angle is to increase solar production, but also to shed snow (I'm in Colorado). System doesn't have to be perfectly to code, but I'd like to respect the wind threshold (90-basic; 115-ultimate) and obvs general structural parameters. Side note: I don't care about the bifacial potential. These panels just happen to be available new from a local, commercial installer at a good price ($200 ea) and when you live in a small town, you grab what you can when you can!

What racking system would you recommend? Tips are welcome! Thanks!
 
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Welcome to the forum, and nice score on getting those panels.
You don't say what the roof pitch of your Tiny house is, or what kind of support structure it's made from, although that may not matter much, read on.
Most 'tiny homes' are trailer mounted - to avoid certain rules and regulations...meaning it is likely narrow, but tall-ish, and on wheels/blocks.

I have roof mounted tilting arrays on a steel building - ie very low slope roof 1/2 : 12 pitch - but there is heavy steel under the roof sheets to secure the tilting framework. I fastened through the roof sheets and through the underlyine steel framework to hold mine, and used quality sealants.

We see many solar racking systems for metal roofing that just screw to the sheeting alone with some profiled clips. This can be problematic, if not carefully planned for the local wind loading, and can lead to water leaks especially with light (thin) roofing stock.
Wind loading is a function of windspeed, exposure (ie out in the open is not the same as beside a rock-outcrop or trees) the lay of the land (flat vs hilly) etc. and the area of you PV exposed to the wind.

Those 6 panels at 33.5 sqft each present a large sail area of approx 200sqft. in total.
You can look up local wind loading requirements but if you imagine 200 sqft x 25lbs/sqft you quickly have 5000 lbs of force to deal with.
If the centre of the array up on the roof is say 16 feet above the ground your tires are sitting on, the over-turning moment - just from the PV would then be 80,000 ft.lbs, add this to the wind loading on the long side of the tiny home and you will quickly see how this adds up to trouble.

Recently in the news a wind storm blew over some rail cars on a rail siding, and you know those cars are very heavy even empty.

If the tiny home is a trailer mount, I would suggest either going parallel with the roofing to cut down PV wind exposure, or build a ground mount set into earth. Some duck-bill anchors may be a good idea even just for the tiny home if the broad-side wind exposure is high.
 
Thank you! All very excellent comments. Unfortunately, my 13' roof is also 1/2:12, hence my interest in creating some pitch. Doubly unfortunately, I don't own my land so I'm reluctant to build a permanent ground mounted system. To be sure, this isn't something I'll be DIY-ing, but I wanted an idea of feasibility and equipment. I'll get some local installers out and see if there's a happy medium between enough pitch to slow snow while generating adequate power and staying safe. If not, it may be a ballasted ground system and hopes for a light winter!

PS where in NW Ontario are you? I grew up in southern Ontario.
 
Thank you! All very excellent comments. Unfortunately, my 13' roof is also 1/2:12, hence my interest in creating some pitch. Doubly unfortunately, I don't own my land so I'm reluctant to build a permanent ground mounted system. To be sure, this isn't something I'll be DIY-ing, but I wanted an idea of feasibility and equipment. I'll get some local installers out and see if there's a happy medium between enough pitch to slow snow while generating adequate power and staying safe. If not, it may be a ballasted ground system and hopes for a light winter!

PS where in NW Ontario are you? I grew up in southern Ontario.
If I was in your situation I would be thinking about a covered porch area - and if your tiny home is on wheels, then put the porch on wheels too, but side-by-side and temp-connected (while parked) so the porch and house together resist any over-turning from wind.
If you use linear actuators like these: Mine are designed to tilt between 30 and 72 degrees but you can build yours to suit your requirements.
IMG_5518.jpg

The array can be adjusted quickly back down to a low angle for high wind condition. I bought four of these actuators off Aliexpress - they work well and are available in several voltages - I used 12v DC to suit my smallerst mobile inverter -you could wire actuators into your system and set up controls based on an aerometer input or just a 2P rocker-switch.

PS - farm area near Dryden, nice & quiet, with good neighbours. I was born in Southern Ontario, a few million years ago - or so.
 
Funny you suggest this as this is/was an option I was considering as I don't currently have a deck or awning. To make things as simple as possible (this is year 1 of off-grid living so really a test year for all things), I'm thinking I could just create a shed roof with the panels with the high end against the tiny house and the low end hanging over the front of the deck. If I can create a permanent 30 deg angle, I'd be more than happy with that.

I can actually say I've been to Dryden, at least I drove through it on a cross-country tour many moons ago...!
 

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