Panel selection and install design for pick up truck topper

[BirdDog]

As a dyi solar newbie, I have a few questions regarding proposed 200 watt panel install on my truck's ARE fiberglass topper.

Background:
My truck topper has an existing Yakima roof rack system that I often use to transport paddleboards. I want to attach the solar panel directly to the rack system roof track rails using anchors inserted into track rails. To reduce the wind resistance, I don't want to attach panel on top of rack crossbars so I can still use the overhanging crossbars for my paddleboards.

The unobstructed surface available within the constraints of the rack system‘s crossbars and rail tracks is an area of 46”length and 36.5” width.

My current panel of choice is a single 200 watt Rich RS-M200 (mono) which has a length of 58.7” and width of 26.8”. I want to keep the panel width less than than 36” between the track rails.

The proposed 200 watt Rich panel length will extend beneath the rear rack system crossbar, resulting in a constant shading of almost 10% of the panel‘s PV surface area (without the paddleboards). I don’t have a brand preference, priority is optimizing dimensions and minimizing wind resistance.

Questions:
1. Will the the crossbar shading (up to 10%) only reduce the panel’s wattage output by the same percentage?

2. Assuming the panel is fastened securely to the rack system rails, do I need to be concerned about damage to the panel from excessive wind loadings on the highway?

3. Is there another panel with dimensions that would better fit my truck topper roof surface area constraints?

4. Are there pros and cons of using one panel instead of two?

 

[MisterSandals]

1. Will the the crossbar shading (up to 10%) only reduce the panel’s wattage output by the same percentage?

my guess would be a much higher percentage.

2. Assuming the panel is fastened securely to the rack system rails, do I need to be concerned about damage to the panel from excessive wind loadings on the highway?

People have been putting these on RV's for years. I have never had any issues or concerns about mine, nor have i heard of any wind damage. I suspect there are wind ratings, google might shed some info. Florida is the crash test dummy for this every year.

3. Is there another panel with dimensions that would better fit my truck topper roof surface area constraints?

To think out of the box, why not mount it so the length of the panel goes across the roof? Is there a reason to limit yourself to the width of the tracks?

Check craigslist for big cheap panels in your area. Maybe eBay and sort by distance to locate some you could pick up. The dimensions should be listed or easily acquired.

4. Are there pros and cons of using one panel instead of two?

Mostly just the number of mount points (nuts, bolts, brackets). If you can manage the volts/amps by wiring series/parallel to match your SCC, that's the big electrical concern.

 

[Dzl]

Questions:
1. Will the the crossbar shading (up to 10%) only reduce the panel’s wattage output by the same percentage?

No, shading is f**ked up with solar. losses due to shading are often severely disproportionate to the amount of the panel that is shaded. But how much will be based on the specific panel you have, how optimized for shade it is, and how it is oriented.

2. Assuming the panel is fastened securely to the rack system rails, do I need to be concerned about damage to the panel from excessive wind loadings on the highway?

Probably not, but its something to be conscious of.

3. Is there another panel with dimensions that would better fit my truck topper roof surface area constraints?

Probably, but that'll take some searching. Would be cool if there was a database of solar panel dimensions.

4. Are there pros and cons of using one panel instead of two?

Off the top of my head
One: slightly more space efficient, less connections, wires etc, better looking maybe, often higher build quality if residential or commercial panels.
Two: If in parallel better shade tolerance, better frame to surface area ratio, more flexible mounting and config options.

 

[Dzl]

Found a 170W panel from a top tier brand that is ~ 45 x 32 inches, its a flexible panel though which wouldn't be my preference.