Solar Car

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HintLightbulb.png Hint: Newer work is found at Book - Solar Car

  • Solar Challenge 2 time winner - 2009, 20011 - Tokai Challenger - 62 mph average for Solar Challenge Winner- 1.8 kW PV array, 30% efficient, 352 lbs, 16'7" by 5'5" - [1]. 90 square feet of area.
  • Increase that to 24 feet long x 8 feet wide (192 square feet) (2 kw) - like a trailer - to double the area. Use non-exotic solar panels to keep cost reasonable with solar. Add 20 kg of lithium ion batteries for 4 kWhr [2] of power, and a small backup engine (2kW) - for one hour of up to
  • PV panels - 1650x990 cm is 17.5 sf. See slide 12 of Open_Source_PV_System#Initial
  • 11 of these panels fit on the 192 sf area. Each is 285 watts for 3100 W total. Under normal conditions - power should be 1.5kW. If we double that with an internal combustion engine for 3-4kW - we are pretty good to go for sppeed.
  • The main challenge in using Open_Source_PV_System#Initial PV panels is that they weigh 19kG each - so 209 kg total. That is 460lb already. Small engine would be 5 lb, and batteries at 44 lb - with frame + drive at 240 more lbs. That makes for a 750 lb vehicle.
  • Can we get frame to within 240 lb? Yes, with carbon fiber composites. But aluminum would be tough. Suggestion: 3D printed frame as skeleton for carbon fiber layup.
  • Frames - carbon fiber is 5x less weight than steel frame, and 2x less than aluminum. [3]

OSE Implementation


  • For a practical 200mpg equivalent solar car for OSE, we can think of a box truck with a roof to carry 20 solar panels, 2 2kW silent generators for auxiliary power, and open source electric motors. It would also have a 1Kw battery pack from r rapid acceleration,such as 20kW boost for 3 minutes.
  • Solar power would be on the 24x8 foot roof - 200 SF for 3kW of power. There would be telescoping extensions to double power to 6kW for cruising speed.
  • It could potentially telescope to 9kW total when standing for rapid charge, but this may not make much sense if small size and small battery pack are used. $1k gets us up to 3.3kW of battery storage.
  • This would be quite the vehicle with battery, solar, and wood gas.
  • Carbon neutral, unlimited range.
  • Practical
  • Curb weight of 1000lb with plastic fiber composites that are 3D printed.
  • 120lb generator for 3 running kW
  • 3kW panels (30 panels) weigh 96 lb.
  • Structure - 500 lb
  • Motors - 100 lb for 2x10kW running power
  • Batteries - 15 kg for 3kW
  • 9 running kW - 40kW peak for 30 seconds
  • 3D printed airless tires

Specific Case 1 - Telescoping 32' vehicle

  • Vehicle lengths in the USA are typically 65' [4]
  • Vehicle telescopes, so it has a a normal length of 20' (size of a van) to 30'.
  • This is 8x65=520 square feet, or 48 sq m.
  • Take a Sunelec panel - [5] - Heliene 300 - 65.5 × 39.4 in - for 300w. [6]. 2581 sq in or 1.67 sq m. This is 180W/sq m.
  • There are 29 solar panels in this area.
  • 48 * 180= 8.6 kW
  • Thus, a large trailer would have a total energy capture of 8.6 kW (11.5 hp)
  • This is plenty for driving on flat land.
  • Typical rolling resistance is 1.5 hp for 1000 lb of vehicle. [7]. We can allow for a 2000 lb vehicle to make this easy.
  • Each panel is 50 lb [8]. 29 panels make it 1450 lb - leaving only 550 lb for everything else - which is difficult. There is a strong case for flexible panels that are 82% lighter [9]. In which case the structural engineering is easily doable without extreme performance design.
  • Flexible panels are not as durable.
  • Case exists for a heavier vehicle with stiff panels.
  • Say 3000 lb weight - but that gets into pushing too much mass around. Doable. With 11.5 hp available, 4.5 goes to resistance, and 7 hp to drive (5 kw).
  • There would be a 20kW auxiliary battery pack for added power.
  • All together, this makes for an interesting city vehicle that can also be designed for highways.
  • A telescoping vehicle is one route to try, and it is definitely a viable idea.

Case 2 - Non-Telescoping 21' Vehicle

  • 2.9kW power. 21'x8'= 168 sf.
  • Low-rider back with panels - 10 panels - 500lb
  • Total vehicle weight - 1000lb
  • Onboard hydrogen compression plant - trickle compressor, runs all day.
  • Storage - see Hydrogen Storage