12 replies to this topic

[Bwht4x4]

I am in the middle of slowly installing my new 160 watt solar panel.  I chose to use angle aluminum attached to the long side of the panel to span and attach to my Yakima tracks.  Installed as you see here I have about a finger width of space between the angle aluminum and the roof panel.  Does anyone think or know if the roof panel will/could flex enough that the two could touch?  I have the option of increasing the height if I need to, but if it's not going to touch then I'd like to leave it as it is.

 

 

Edited by Bwht4x4, 01 May 2014 - 02:48 AM.

[craig333]

I'd be greatly surprised if thats not enough clearance.

[ntsqd]

Agreed, but something to consider is ventilation of the backside of the panel. From what I've read a PV panel performs better when the backside of it has good ventilation. I set ours up about 1-3/8" of off the roof, I made the front mount shorter by a 1/4" so that water would drain off of it when parked level and to create a high side for convective airflow. I also drilled the panel frame at the high end, put four or five 3/4" holes in it so that the hot air could escape.

[Bwht4x4]

The way I have the panel installed currently there is a 1/2" to 3/4" opening all the way around the panel to provide ventilation.  Many of the other installs I've seen they install the panels with "z-bar" that only allows for venting on two sides.  I think with my four sides being open I come close or exceed those other installations.  I currently have it sloped too, but one thing I could do is add a shim to only one side to get more slope and a little more ventilation.

[ntsqd]

Whatever the depth is of the panel's own frame is 'captured' air volume. Turbulence from going down the road will slowly exchange it, but sitting somewhere the exchange rate will be low due to it being driven by the air's thermal expansion only. What I read was that the front and backside need to be as close to the same temperature as is possible to get the best performance in any particular set of conditions. Which is why I drilled the large holes. Now the 'captured' air isn't any more. Now as it expands it can rise out the high end and escape. No idea how effective they are, but I feel better about it all with them there.

[Bwht4x4]

Wow, I was surprised and had to report that the space between the angle aluminum that supports my 160 watt panel and the roof was not enough.  I was working on the solar wiring today and noticed that there was a black line on the roof from the angle aluminum and the roof touching while traveling down the road.  The roof was not creased or damaged at all, but in time I could see it causing a problem.

 

So, to remedy the issue I added a 3/16" piece of aluminum flat bar under the mounts on the Yakima tracks to lift the entire system up a bit.  I'll use it like this for a while to see if this cures the situation report back.

 

Here's a couple of picts of the flat bar I added to raise the system up a bit more from the roof.

 

 

[craig333]

Interesting. I'm going to have to go out and measure my clearance. Okay, I have only 3/8" of clearance (I thought it was more) at the minimum but no signs its touched the roof. Its easy to raise. I may do that just for more airflow underneath.

[Bwht4x4]

Craig,

 

I was unable to tell the roof and support bars touched by just looking from the top.  The only way it was visible was to remove a couple of bolts and tilt the panel up and look under it.  I had a longer black line along the front and a shorter line on the rear.  I have a feeling that this is more likely to occur with the newer seamless roofs and unlikely to happen with the older roofs.  I imagine the older roofs that are screwed down wouldn't flex up and down as much traveling down the road.  I have a big road trip next week and will recheck this when I get back to see if the added piece of flat bar cures it.

[mangymarmot]

Hey Craig,

How is your solar panel attached to your Yakima track? Are you just using the metal tabs that float in the tracks to bolt to.....?.

Thanks

[craig333]

Mines not a yakima. Homemade rack.