Solar RV with Multi-Function Aluminum Weldment
How do you tilt, rotate, store, and transport at 65 mph; a 6’ by 2.5’ glass panel on top an RV camper?
Photovoltaic (PV) solar panels produce electric power when the sun’s photons strike silicon crystals displacing electrons, from the front surface to the rear surface of the panel. The resulting build-up of electrons produces a voltage, thereby causing an electrical current to flow when an electrical circuit or load is connected across the panel.
In this RV application the solar power generated by a 125 Watt PV module, during a 16 hour long Wisconsin summer day, is about 750 Watt-hours with the panel stationary. The panel is comprised of 36 individual PV cells, bonded on a 15 ft2 tempered-glass pane, and electrically interconnected to produce 7.1 Amps at 17.5 Volts d.c.. Inclining the PV panel to match the arch of the summer sun and rotating the PV panel to follow the sun, increases the solar power available, to about 1,000 Watt-hours or 1 kWh/day. The solar electric power is used directly during the day, or stored in batteries for use in the evening hours and on rainy camping days in Wisconsin.
Family solar camping or ‘off-grid living’ involves; mp3 players which come with grand-kids, cell phones which come with teenagers, GPS systems which come with sons, hot (pressurized) showers which come with daughters, hair-dryers which come with wives, outdoor ‘green-n-gold LED rope lighting’ for the Packer Fans, plus digital instrumentation for engineers. Yup, this is high-tech, but it is also outdoors - it is in the wild - and it is camping! See the included photo of the Solar Family Campsite.
We still use wooden matches, but they too, like canvas tents, are becoming collectibles.
An Essential Welded Component, of this solar family campsite, is a ‘double-cross-bar H’ frame supporting the 15 ft2 glass pane contained in the solar panel. Early in the project this multi-function frame was identified as critical, and the concept for a weldment was developed. The final solution is a rigid, light-weight pulse TIG welded structure of 2”x2”x3/16” aluminum angle, including SS spring-release hinges for tilt pivot points, and SS quick disconnect ball-joint rods for tilting and lowering the panel for storage. To rotate the panel, a SS ball bearing turntable mounted on a high-density polyethylene, HDPE, sheet is used. Transporting the panel, at 65 mph, requires the pivot hinges to be faced forward, the PV panel to be stored horizontally, and four elastomer drawn-down latches to be set. To protect the glass pane from highway debris impacts, its 4-1/2 feet above the road surface, a laminate cover of heat-formed PVC sheet and closed-cell insulation is placed on the panel before the draw-down latches are set.
The resulting TIG welded aluminum frame, incorporating the above five functions, has proven easy to set-up, rotate, and store; while reducing the wind load on the drawn-down latches. In addition to the;
high-efficiency, multi-crystalline silicon solar module,
max. power point tracking and battery-charge controllers,
two, valve-regulated, absorbed glass mate lead-acid batteries,
a battery status monitor and display, and
a 800 Watt inverter to convert battery power to 120 Volt, 60 Hz (for the hair-dryer),
the TIG welded aluminum frame is an essential component for a practical solar family campsite.
Warren Herwig, P.E.
Sr. Staff Engineer
Miller Electric Manufacturing Co.
Manufacturing Process Technology
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Thread: Solar RV Weldment
10-19-2005, 02:53 PM #1Miller Electric Guest
Solar RV Weldment