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I've been trying to figure this out, but the answers I've come up with thus far have been counter-intuitive.

The solar panel's specs are as follows:

Maximum Power: 50W 
Maximum System Voltage: 600V DC (UL) 
Optimum Operating Voltage (Vmp): 17.8V 
Optimum Operating Current (Imp): 2.8A 
Open-Circuit Voltage (Voc): 22.4V 
Short-Circuit Current (Isc): 2.95

The motor's max volts is 30, and max watts is 4800, presumably bringing the max amps is 160, and by this measure, it seems I would need nearly 50 of my solar panel to power the motor... is this right, or am I misunderstanding something? If I am, how is anybody achieving anything with solar? This is a small motor for an RC boat :/

This is the motor in question (more for trucks than boats, but oh well): Turnigy TrackStar 1/5th Sensorless Brushless Motor 760KV

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  • \$\begingroup\$ A 4.8kW motor for an RC boat? :O \$\endgroup\$
    – brhans
    Commented Oct 14, 2014 at 1:57
  • \$\begingroup\$ @brhans it's a really powerful one, but the smaller ones are in the 800-1200 watt range on hobbyking.com \$\endgroup\$
    – orokusaki
    Commented Oct 14, 2014 at 2:09
  • \$\begingroup\$ @brhans maybe this is just an AC vs DC sort of confusion on my part? It's so frustrating, because I cannot fathom 50 square feet of solar panels to power an RC boat, yet I know too little to really make the case otherwise. \$\endgroup\$
    – orokusaki
    Commented Oct 14, 2014 at 2:16
  • \$\begingroup\$ well.. if you really need a 4800W motor (I second @brhans's :O ), then you'll need 4800W / 50W panels \$\endgroup\$
    – kolosy
    Commented Oct 14, 2014 at 2:32
  • \$\begingroup\$ 50sq ft is on the right order of magnitude for a solar demo car, and 4800w seems about right for a wimpy go-cart, so while I'm sure the figures aren't quite right they do seem in touch with reality - solar means big surfaces, featherweight construction, sublimely efficient mechanisms, and highly strategic operation. \$\endgroup\$
    – Chris Stratton
    Commented Oct 14, 2014 at 2:43

1 Answer 1

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The answer is simple:- you chose the wrong motor. For your application you need to turn a large prop, but not very fast. So you should be looking for a geared motor or an outrunner, with a rating of at least twice the power you will put actually into it (because you want to run it at close to peak efficiency, not maximum output power).

12V trolling motors typically draw about 500W, which would require 10 50W solar panels. Put the same power through a low Kv outrunner such as the Turnigy Aerodrive SK3 5055-280kv, and you should be good to go. The only other question is what size prop do you need to draw that power?

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