Can someone give me the rundown on PV panels for mobile applications

[fastline]

I am primarily familiar with commercial stationary panels. I support an RV with solar currently by parking it next to a semi trailer where I mounted panels on that trailer roof. Would sure be nice to have solar on the RV itself but those roofs are both complex, and I question the attachments for a good wind rating.

What is common on this stuff?

 

[ianganderton]

Not entirely sure what info you are after so here are some random statements I believe to be valid

Flexible panels are popular and light but don’t last well permanently mounted. They tend to be mounted too close to have any airflow under them and the heat generated causes hotspots that kill them

Big panels are much more difficult to mount on vehicle roofs than smaller panels. The weight can be challenging to deal with

Solar arrays work much better if made of matched panels

As a rule of thumb it’s worth putting as much solar on the roof of a vehicle as will fit. It is extremely rare to here “ I wish I hadn’t installed as much solar!!”

Panels of different sizes can be used by using seperate solar charge controllers. This is very common on sailing boats because of the complicated shapes of the space available and the shading issues

You can use a solar irradiance table to estimate an arrays daily average pv energy production.
I like this one for its simplicity

Solar Irradiance Calculator

www.solarelectricityhandbook.com

There are lots of ways to attach panels to vehicles but it depends on the roof material and shape as to what is best. A panel coming off the roof of a moving vehicle on to a road has been proven several times to be a killer so it’s worth doing it properly

I used 120W panels x 4 mounted between the bars of a roof rack. Feels rock solid



Hope this helps a bit

 

[redrockkevin]

I am primarily familiar with commercial stationary panels. I support an RV with solar currently by parking it next to a semi trailer where I mounted panels on that trailer roof. Would sure be nice to have solar on the RV itself but those roofs are both complex, and I question the attachments for a good wind rating.

What is common on this stuff?

I have Merlin's comes with sticky back company is in San Jose CA

 

[fastline]

I appreciate the comments on flexible panels. I have no experience with them and I recall their performance to be quite a bit less than rigid commercial. I was not aware of any hotspot issue but that does make sense, though I have no idea how they might even be mounted. My thought was I would have to design a custom radius support for flex panels, then have to figure out how to make them survive the wind.

I see your rig and setup, but in the USA many RVs are a radius roof with EPDM or TPO membrane on them. Shooting holes in that roof is just asking for leaks and serious damage.

I work in structural engineering and could solve the attachment issue with enough information, but I highly doubt any OEM is going to provide me what I need to feel good about any attachment. I've never seen a factory install but most are only a couple hundred watts anyway and I am looking at closer to 1.5kw.

 

[redrockkevin]

Not entirely sure what info you are after so here are some random statements I believe to be valid

Flexible panels are popular and light but don’t last well permanently mounted. They tend to be mounted too close to have any airflow under them and the heat generated causes hotspots that kill them

Big panels are much more difficult to mount on vehicle roofs than smaller panels. The weight can be challenging to deal with

Solar arrays work much better if made of matched panels

As a rule of thumb it’s worth putting as much solar on the roof of a vehicle as will fit. It is extremely rare to here “ I wish I hadn’t installed as much solar!!”

Panels of different sizes can be used by using seperate solar charge controllers. This is very common on sailing boats because of the complicated shapes of the space available and the shading issues

You can use a solar irradiance table to estimate an arrays daily average pv energy production.
I like this one for its simplicity

Solar Irradiance Calculator

www.solarelectricityhandbook.com

There are lots of ways to attach panels to vehicles but it depends on the roof material and shape as to what is best. A panel coming off the roof of a moving vehicle on to a road has been proven several times to be a killer so it’s worth doing it properly

I used 120W panels x 4 mounted between the bars of a roof rack. Feels rock solid

View attachment 120427

Hope this helps a bit

Except Merlin's I have had mine for years

 

[SolaroSsaurius]

Search for a very recent YouTube video on some flex panels starting to burn on the top of an RV.
In a previous RV, mine were glued.
In the next one, alu supports will be glued, and panels will be attached to the alu frames (roof is not flat)

 

[Bobert]

I am primarily familiar with commercial stationary panels. I support an RV with solar currently by parking it next to a semi trailer where I mounted panels on that trailer roof. Would sure be nice to have solar on the RV itself but those roofs are both complex, and I question the attachments for a good wind rating.

What is common on this stuff?

It depends on the type of roof your rv has. Most roofs have some sort of “rubber” membrane glued on a decking. That decking can be between 1/4 inch thick (non walkable roof) and 7/16 inch thick. If the decking is 3/8 thick or better and in good condition residential or commercial style panels are commonly mounted with screws, brackets and dycore to the roof. This is not an adequate method for non walkable roofs in my opinion. The most common loss of panel situation comes from placing panels too close to the front of the trailer and having the panels ripped off the roof. The nature of a moving vehicle is that the front of almost any rig sees hurricane strength winds pushing upward during normal travel at the front of the rig and generally disorganized breezes from that point back that are enough to flap around unsecured PV wires but not enough to lift even a poorly secured solar panel. Being passed by a fast moving semi truck can temporarily change that and side winds of 75 mph are a good possibility even when off the highway so the panels all need to be well secured. I needed to mount my panels 8” above the roof and extremely close to the front of my travel trailer so I built an airfoil to insure that no wind gets underneath the panels. I used extra heavy duty aluminum brackets that are screwed with 1/4” lag bolts to the decking in addition to a tpo compatible adhesive/sealant underneath and on the the threads of the 1/4” bolts. I have done extensive involuntary test testing of this system and it has proven to be more than adequate. The first test was a short camping trip where the airfoil started to come apart. I was able to patch it and complete the trip. The new design has had no signs of cracking or peeling on our most recent 1700 mile trip. This summer we had a storm that blew a 16” tree onto the solar array and totally destroying 3 of the solar panels and punching 2 of the brackets through the decking and bending several other brackets. When I was doing the repairs I discovered that the brackets were very difficult to remove even with the screws removed and that even with all the trauma none of the screws had pulled through the decking although several of the bolts had ripped through the solar panel aluminum frames. I am confident that the roof attachment system I have in place exceeds the strength of the solar panels themselves and have the panels attached in 3 places on each long side instead of the traditional 2. The following thread contains a video showing the heat issue that flexible panels can have.

Flex or non-flex panels for RV?

Hello. Soon I will be adding solar PV to my motorhome (45-ft class-A). I have a pretty good amount of room on my roof, since my air conditioners are not on the roof. I intend to add as much solar PV as space will allow, possibly 4kW if I can fit it (perhaps 3kW if I am being more realistic)...

diysolarforum.com

 

[HRTKD]

I see your rig and setup, but in the USA many RVs are a radius roof with EPDM or TPO membrane on them. Shooting holes in that roof is just asking for leaks and serious damage.

If you do it right, it's not a problem. I have two 320 watt panels on the roof of my RV. I used six Z brackets on each panel to make sure they stayed put. I was very careful with where I placed the mounting brackets on the roof to ensure that each bracket was anchored in a roof truss by at least one screw. Here is a link to my install write-up. If I add more panels, I'll likely use a different mounting method like Unistrut.

How To: Mount Panels to an RV Roof

This details the steps I went through for mounting my Mission Solar 320 watt panels to the roof of my RV trailer. While there are multiple methods to secure a panel to an RV roof, this focuses on using standard Z brackets. Other methods include DIY brackets, Unistrut, adhesive tape and all the...

diysolarforum.com

 

[Rocketman]

A lot depends on the roof material. I have a fiberglass roof, I used vhb tape to attach a 2”x6” bracket down (four per panel) added a screw though the roof only on the brackets on the front of the rig. Dicor to seal the elements from the tape. In three years and 20,000 miles the Dicor hasn’t even cracked (no flexing).

Having a really good roof helps?.

 

[HRTKD]

Having a really good roof helps?.

I figure if I cover the rubber roof in PV, the rubber should last twice as long!