Solar panel system design
After a few days of thinking, I finally found my way. Not pretending it is the best, but it surely fits the bill of my requirements. First, the panel. Since I wanted 400-500W solar system, it was cheaper to go with a high voltage solar panel (36V). 235W panel sells for 350$, about the same price as 130W at 18V. The drawback, if it’s one, you need a MPPT charge controller to convert higher solar DC voltage to the RV battery system. The MPPT is more efficient anyway (10-30% depending of the conditions). Other benefits, I’ve used 10 awg cable for the 35ft PV cable run without losing more than 1%. I had connect the 2 panels in series, so there is about 72V at the input of the MPPT. 10% gain with the MPPT is another 47W free at 2$/W it’s 100$ to pay the prime MPPT.
Model used: Tri-Star 45A MPPT.
Installation of the panel
I wasn’t convinced with the design of the standard Z clip. They create a pry effect on the anchors. This means they add more loads to them, especially in the uplifting condition. A rigid connector as I did use prevent this leverage. I ve used a square aluminum tubing (1.5 x 1.5 x 1/8) cut at an angle to provide access from the top to the anchor. I was short in stock…so I did 2 angled cut.
If I was redoing, I would use this model. It has more contact surface.
The only place I could fit both panels was in the front of the travel trailer. I dont want to have the panels sucked off the roof!! So I did install a small wind deflector using a scrap flashing trim to prevent this. Also, because of the scale of the panel (65in x 38in), I wanted rocksolid anchors.
I did scan carefully the structure of the trailer. I realized that the C shape metal roof truss are only 1in wide and are doubled ( back to back) every 4ft at the plywood edges. Because the front anchors are at a plywood edge and I wanted to assure to grip in the center, thus the spacing between front and back anchors are 32.5in instead of 32in. Be carefull!
Lastly, I don’t like to mix stainless steel and aluminum material as galvanic corrosion potential is great. I assume and hope water won’t stay too long!