Electrathon America Forum

alex e · Newbie

Solar Panels

Kyle Keenan · Veteran Member

I tested once (when our car was running....for once) with a panel taped to the canopy of our car. Granted it was about 12" by 16", and was hooked to only one battery.

I'd be surprised if it did anything, but for the weight, it's almost something I might consider, providing we have a sunny day for once...

electrathon · administrator

Yes. you will still drain you batteries. Even on a sunny day. In order to get 20 plus amps out of a set of panels you would need a lot more surface area than you have on the car. Possibly someone can step in that has direct experience (maybe the OSU team will show up) but I am guessing you will need to spend about $20,000 in panels and have the top of the car larger than a sheet of flat plywood to get serious return back.

Using panels will also put you into another class of cars, so depending on where you are at there may not be any local solar class races.

Date: Sep 12, 2010

alex e wrote:

If you have solar panels on your car does it keep your battery charged the entire race? or does the battery still lose power?

Depends a lot on the solar panel, the track, and time of day.

Assume using two high output panels like a Sharp ND-224U1F, on a fairly flat track around noon in the late spring or early fall, and you can pickup an additional 450 WHrs during the race (nearly 50% more power), and charge the car in about 3 hours mid day.

The panels are 64.6" x 39.1" x 1.8", so two would fit a 12' x 4' car with the drivers head out the middle, and the car would be shaped like an aircraft carrier on wheels.

In practice that's enough power using a relatively clean design, to run about 45mph without batteries for an extended mid-day period, assuming mild to no wind.

I would not try to break the 62mph record with that surface area.

It might be fun to create a LiFePO4 battery class, that limits batteries to 200WHr plus solar. Solar would recharge in about 30-40 min between races.

John Bass, Sr. Engineer, DMS Design

Date: Sep 13, 2010

It's interesting to find students actually trying this :)

In the race pictures posted we have: http://www.kansaselectrorally.org/images/Clearwater%202010/Race%202A.JPG

The first car with the larger rectangular cell, appears to something in the 30-50W range - about 5% of battery capacity - not a lot to be significant.

The second car with the pair of automotive solar maintainers, only has a few watt's best case. Most of those type of panels only produce a fraction of an amp at 12v.

It would be useful to help the students do the math, and make a better judgement about getting put into a different class because of the solar ... on the other hand, that might be the goal, even with a worthless panel, it might be easier to win the class when you are one of three cars in the solar class.