Hi Guys,

I know Adam Harper made a Solar Powered C5 for Arthur C Clarke, I managed to find pictures of it before, but I can't find them anymore.

Anyone have a copy, or have a link to one I can have a look at? I'm going to fit a 100W panel to my own C5 to give me a bit more range in the summer, so I was looking for a bit of inspiration on the frame design.

Cheers John

Went and did it :-)

Hi John,

don't keep us on tenderhooks, let's have a shufti.:-" :-"

Cheers.

Karl.

Hello John
I would love to see some pictures...

Check out the Gallery :-)

And here

https://www.facebook.com/photo.php?fbid=10206107936918352&set=pcb.610640605733839&type=1&theater

Hi John,

well done. I might take up the idea, but mounted on a trailer, otherwise I'll never get my C5s onto the road. Plus if mounted like yours I'll have parking problems.

Cheers.

Karl.

Yea that would work. I did think of that, but this suited me better.
This is a 100w panel from eBay, it's a lightweight flexible one so it's only added about 2kg in weight with the alloy frame and fibreglass supports.

I also used a 120w solar charge regulator to stop it overcharging the battery.

One bounus I did notice is that it helps keep the voltage up when on the move, so it helps keep the current down. Bound to help delay overheating!

Hi John,

you have me lost with your last sentence.

One bounus I did notice is that it helps keep the voltage up when on the move, so it helps keep the current down. Bound to help delay overheating!

The amount of current needed to run the C5 will remain the same regardless of solar charging or no solar charging. So the heat will remain the same, if anything it will rise somewhat because of the extra drag.

The drag factor is also one of the reasons for wanting to mount the panel on the trailer (as part of the lid). The extra drag will be more or less the same with or without the panel.

There is a solar panel available that is similar to foil, super light and can be rolled up. I've no idea what the cost is, and it'll be some time before I start to have a look around.

Hi Karl,

No It needs the same power, but the current does the heating. The voltage drops quite a bit on the move, with the solar panel the voltage stays 1 - 1.5 volts higher than it did when running without it. So correspondingly the current is lower.

Remenber P=I*V in a DC system, but Heat generation is governed by P=I^2*R, so as the Current increases so does heat generation. Therfore if the voltage is higher, then heat generation in the windings is lower for the same power as it needs less current. As I can see figures on my meters on my C5 rather than the LED bars of the original I can confirm I'm pulling less current out on a run on a sunny day than before due to the higher voltage seen in the system.

http://www.ohioelectricmotors.com/dc-motors-high-efficiency-designs-782

I've not noticed any change in speed or difficulty pedaling since fitting the panel, but it is pretty thin at 2.5mm, with a lightweight 10*15mm angle section Aluminum for support. I don't think it's adding much more drag, but I am operating on a 12V system, and don't go above 15mph too often, just down hill when I'm braking anyway. You might notice it on a 24V model.

I've not seen any foil solar panels, but there are roll up ones but they run at high voltage for use on roofs for domestic supplies. Your best bet at the moment is to go for the lightweight flexible ones and make a lid for your trailer with them.

Cheers John

Hi John,

you are correct when you say the current causes the heating, but you are ignoring Ohm's law.

Ohm's law: I = V/R, or V = I x R, or R = V/I, where I is current, V the voltage, and R the resistance.

R in this instant is the motor resistance. This is hard to calculate accurately due to such factors as RPM (back EMF), heat etc.

So let's say the rpm, heat, etc. remain constant, this means that R is not variable. Now if you take a 10Ω resistor and apply 10V to it 1A of current will flow, if you up the voltage to 12V then the current flowing will increase to 1.2A. As heat produced is in relationship to the amount of current flowing the heat will increase, not decrease.

According to your theory, if you apply 18v to a 9v radio the radio will produce less heat, try it and see what happens. I can assure you it will be the black death.

Please don't think I'd disputing your findings, but to get accurate results you would need a testbed. The slightest variation in pedal pressure, increase/decrease in gradients, RPM, etc will alter the test results.

With respect to everyday use the performance of the C5 will be enhanced by the use of the solar panel, but don't rely on less heat.

The empirical evidence I have shows a lower current, when out in daylight, the load is the same on the same roads, same speed therefore same power therefore lower current with the higher voltage.

On the flat at 14.5 mph I get 12.5 V at 28 amps with the panel where it used to be 11.5 @31 amps 350 watts vs 356 for the same speed. The 3 amps isn't much but is good to have! It's definitely less waste heat and less drain on the battery. (About 22% more waste heat) Need to try it on the same road in the dark with no wind see if it drops back to previous levels:-)

Hi John,

if you are happy, that's the main thing. One way or the other no damage will occure.

Av phun.

Karl.

I'm fascinated by this, 2 things that I would want from it though.
1) I would want it flexible so I could mould it onto the front bodywork. Should look great.
2) It would need to perform well enough to charge up during a days work (on a sunny at least)

What are the wattage limitations when choosing one to work with a C5?

Cheers

Kieron

Great work by the way John

It's not 'powered' by the solar panel but this is a solar panel on one of my C5's to top up the battery when away from a socket.

[img=http://postimg.org/image/w12718kmd/]