For DoubleOhSevan, keeping things low-key is essential. I had originally considered mounting rigid panels on the roof rails, but decided that was still too conspicuous for my liking. A bit more research led to flexible Renogy panels that would fit between the roof rails. These would make efficient use of the roof space and take minimal vertical space. In fact, the roof ridges on either side are actually higher than the panels.
The tradeoff with flexible panels is efficiency (mounting to the roof decreases the circulation and increases the heat. Heat is the enemy of efficiency with Solar modules).
Flexible Panels mounted directly to the roof:
- More aerodynamic
- Less conspicuous
- More expensive (perhaps not if you include mounting hardware for rigid panels)
- More permanent (glued to the roof)
The Renogy 100W flexible panels are 48″ wide, and the distance between the roof rails on a high-roof Sprinter is 52″
- 4 x Renogy 100W Flexible Panels
- 4 pairs MC4 connectors
- 25ft of Red/Black 10AWG PV cable
- 1 pair of MC 4 Y connectors
- 1 waterproof cable entry
- 1/2″ grommet to protect PV cable
- Sixaflex construction adhesive
- 1 40A MPPT Trace Charge controller with MT50 monitor
Total cost (CAD): $1000
- Laid out panels on roof to check spacing (I edned up overlapping them by 1/2 to fit 4)
- Cleaned “ribs” on roof with rubbing alcohol
- Applied liberal Sikaflex to the the ribs and pressed the panels down onto it
- Used scrap lumber to hold the panels down agains the curve of the roof
- Wired in the panels as two parallel groups of two panels in series. Panels run at ~20V so that makes a 40V input the controller.
- Drilled a hole at the front above the drivers side and installed the grommet into it
- Ran the wire from the final Y connector into the cable entry and through the grommet in the roof
- Attached the cable entry to the roof with SIkaflex
- Connected the PV wire to the controller and then plugged in the Y connector on the roof to test.
- Secured the wires/Connectors to the rail using zip ties