solar location on Truck camper

[towpro]

my truck camper has a slanted roof over the bed, and flat over the rear section. I am looking at fixed position mounting of solar panels.
(mostly being used in East coast central US during summer).

If I mount Two 100w panels on the front sloping roof, there will have less chance shadows as only the lid for fantastic fan is between panels. But the con is there could be places where the panels will be on wrong angle for sun. But for where I park the camper at home, it will have around 5 hours of sun per day (trees) and the angled front location would be a positive.


If I mount Two 100w panels on the main body there is more chance of shadows from AC, and Refreg top vent. but they will always be flat so the sun angle will never be worse than horizontal mount location.

What would you recommenced?

[Mello_Mike]

Towpro,
I did both. I installed two 60 watts panels on the forward slant that flank the Fantastic Vent and the third, a 120 watt panel, on the flat part of the roof forward of the A/C shroud. Having it in this configuration allows me to "point" my two angled panels toward the sun for a better approach angle. Of course, for all of these panels I needed a rooftop combiner box.

My Solar Power Installation

[towpro]

Heap64 wrote:

I don't think those and a truck camper play nice together. Not enough real estate.

I would put as much as possible on the front slope and go from there if needed. You won't be needing to walk up there.

I agree, they are 18 feet long if my conversion mm to inches is correct.

[Heap64]

James' wrote:
I've always liked these...
Click here

I don't think those and a truck camper play nice together. Not enough real estate.

I would put as much as possible on the front slope and go from there if needed. You won't be needing to walk up there.

[James_]

I've always liked these...
Click here

[scrubjaysnest]

Ours isn't a TC but took a slightly different approach. 1 - 120 watt mounted to the roof. A pair of 80 watt in portable configuration. The portable set up use 8 AWG marine wire, 25 ' length with separate breakers for each method.

Had a lighting strike 50' from the camper in 2012. No damage, did require a change of underware.

[bigfootford]

towpro wrote:
as I learn more here reading this, explain the necessity for emergency disconnect (Lightening).
I am aware of protection for my amateur radio antennas, but how does lightning play into solar panels?

Well, in theory an ungrounded camper should not be vulnerable to a strike eh?

Hooked to shore power is.

Wet dirty tires etc may provide a path to ground so your camper may have a path to ground.

Hell, aircraft have static discharge wicks don't they.

I personally was present when lightning hit a tree about 100ft from a camper parked next to me. He had solar I did not. Some of his static sensitive electronic devices were..... fried.

Bogart engineering "trimetric" offers lightning protection to the earlier units for a charge. Believe his new units have it built in. No need to ask why...

Some Solar controllers have static/lightning protection built in....


When lightning is in the area I even disconnect my camper radio antenna input along with my tv...

Do I have experience with electronic devices being damaged by nearby lightning strikes?

You bet! Almost 50 years of it in the computer/electronics world... Don't get me started...

Jim

[towpro]

as I learn more here reading this, explain the necessity for emergency disconnect (Lightening).
I am aware of protection for my amateur radio antennas, but how does lightning play into solar panels?

[Buzzcut1]

I use my roof racks for carrying my Kayaks and cargo box way to much to ever consider sacrificing them to the solar set up and I walk around in that area strapping things down to the rack. In 5 years I have never had occasion to walk on the slight forward sloping area of the cabover so that is where my two 100 watt mono-crystalline panels got mounted

[bigfootford]

Golden_HVAC wrote:

bigfootford wrote:

I made mounts similar to these, but my panels are a little closer to the roof. I used 6" long 2" angle aluminum from Home Depot with 3 holes 3/16" for #10 screws into the roof, and 5/16" hole with 1/4-20 screw into the solar panel frame.

You do not need to tilt the panel into the sun, while that is ideal, leaving it flat is only about a 5% - 10% loss. Tilting it away from the sun might give you a 12% loss, but that is still OK if the panels are large enough. And if you are driving every few days, that should fully charge the battery, if you have a large enough wire between the truck and camper!

I ran #10 UV rated grey direct burial romex - also from Home Depot, down the refrigerator vent to the controller and battery.

IF you look for 12 volt nominal panels (19-22 volt open circuit voltage) then you can use a much less expensive PWM controller. SunELec.com sells some in various voltages and with or without frames. Without frame - it would be difficult to mount it to your roof.

Good luck,

Fred.

I debated hard about having an extra inch higher panels off the roof. I wanted to be able to use a brush to clean the roof under the panels... V/S snug to the roof for air flow...
Being able to clean won!

I added a front air deflector for the front panel.... Riding in the camper to listen for any vibration proved that nothing rattled/vibrated. My panels are just pined to the homemade 3X3 aluminum L stock.

For the wire run I used 3/4 electrical conduit and 8 ga stranded wire. Kept the wiring from both panels Isolated until inside the rear of the fridge. There I installed a cutoff blade switch for the + lead going to the Solar controller for emergency disconnect (Lightening). I installed 2 bus bars + and - to combine them. This helps trouble shooting if a problem is isolated to wiring or a panel.

Jim

[HMS_Beagle]

DWeikert wrote:

Jfet wrote:

DWeikert wrote:

This is very dated information. Most solar panels today use blocking diodes so shade over a single cell only affects that cell, not the whole panel.

Bypass diodes, and generally they only use about three, which means partial shading can still shut off 1/3 or more of your panel (depending on the orientation of the shadow).

An exception would be the Unisolar rollout, where they do indeed bypass each cell panel.

You're right, they're bypass, not blocking. Still, I think your info is dated. For example, the Kyocera 140w panel I installed 2 years ago has 8 bypass diodes.

It will of course depend on the panel (8 diodes might mean 4 per string on a 140W). The bypass diode will remove the current block, but also reduce the voltage output. Reduce it by much and you will not have enough to charge the battery. Put a 2x4 across your panel on a sunny day and see what it does. Amorphous Si panels like the Unisolar are less susceptible to shading generally (but also have less output/area).

[Golden_HVAC]

bigfootford wrote:
I cut card board the size of the panels I wanted and found that I could not provide enough room to get around on my roof. I tried placing them all around.
I decided I wanted long/narrow panels so I found some that was 23"X 57" 100 watt.

I again did the cardboard thing and found the perfect placement and accomplished the ability to get around on the roof along with enough room to replace the 12X12 vent over the bed area with an escape hatch.







link to my install:

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/24783458/srt/pa/pging/1/page/2.cfm

Jim

I made mounts similar to these, but my panels are a little closer to the roof. I used 6" long 2" angle aluminum from Home Depot with 3 holes 3/16" for #10 screws into the roof, and 5/16" hole with 1/4-20 screw into the solar panel frame.

You do not need to tilt the panel into the sun, while that is ideal, leaving it flat is only about a 5% - 10% loss. Tilting it away from the sun might give you a 12% loss, but that is still OK if the panels are large enough. And if you are driving every few days, that should fully charge the battery, if you have a large enough wire between the truck and camper!

I ran #10 UV rated grey direct burial romex - also from Home Depot, down the refrigerator vent to the controller and battery.

IF you look for 12 volt nominal panels (19-22 volt open circuit voltage) then you can use a much less expensive PWM controller. SunELec.com sells some in various voltages and with or without frames. Without frame - it would be difficult to mount it to your roof.

Good luck,

Fred.

[silversand]

Among all the roof-mount solar panel examples given here, by far the most interesting (for me) is BKA 0721's set-up, on the roof rack. This set-up is so flexible, you could write a book on why so....excellent method.

If we ever went with rooftop solar panels, this roof rack method is precisely the direction we would go in.

For now, we will probably experiment with manually placing on ground and securing with braided security cable (with a plug-in probably on both sides of the camper, for flexibility)...

S-

[DWeikert]

Jfet wrote:

DWeikert wrote:

This is very dated information. Most solar panels today use blocking diodes so shade over a single cell only affects that cell, not the whole panel.

Bypass diodes, and generally they only use about three, which means partial shading can still shut off 1/3 or more of your panel (depending on the orientation of the shadow).

An exception would be the Unisolar rollout, where they do indeed bypass each cell panel.

You're right, they're bypass, not blocking. Still, I think your info is dated. For example, the Kyocera 140w panel I installed 2 years ago has 8 bypass diodes.

[Jfet]

DWeikert wrote:

This is very dated information. Most solar panels today use blocking diodes so shade over a single cell only affects that cell, not the whole panel.

Bypass diodes, and generally they only use about three, which means partial shading can still shut off 1/3 or more of your panel (depending on the orientation of the shadow).

An exception would be the Unisolar rollout, where they do indeed bypass each cell panel.