# Solar Powered Trike

## Step 3: Charging System / Solar Panels

The solar panels need to be as large as possible to maximize the available wattage, but they also must provide the right voltage. Solar panels produce a range of voltages, which peak and drop, but the nominal voltage of the panel is what matters for selecting the right charge controller. I purchased 3 Q-cell brand mono-crystalline solar panels that I found on Ebay for \$110 each. They produce 21.8 Volts peak and 17 volts nominal, at about 1.2 amps nominal. With the 3 panels wired in series, this makes around 66 volts peak and 51 Volts nominal, which is plenty over the 42V needed to charge the batteries. a basket was added in the front to accommodate the third solar panel.

From Ohm's law Power (P) is equal to voltage (V) times current (I), (P=V*I), so the panels produce ((17Volts*3)*1.2 Amps)= 61.2 Watts nominal, and over 80 Watts peak. A Maximum power point tracking (MPPT) charge controller tricks the panels by hiding the battery load from them and allowing them to operate at their peak power when conditions allow.

A charge controller was purchased from www.solarsellers.com, where Mr John Drake was very helpful in assisting me and ordering a custom charge controller for my application. The controller basically takes the varying voltage / amperage input from the solar panel array and converts it into a constant voltage (42V) or current, to optimize charging the 36 volt source. Maximum input voltage to the controller is 100 Volts, so the peak of 66 Volts will not harm the controller. The controller is a Maximum power point tracking (MPPT) type, which charges faster as more sun is available, rather than at a set rate as most controllers do.

In order to charge the batteries in a practical amount of time, they need to charge about as fast or faster than the provided 110V wall socket to 36V charger/converter, which charges at a rate of 1.5 amps. At 1.2 amps the panels do not quite achieve this, but with the MPPT Controller it takes right around the same amount of time for a charge. The bike is stored in a location that gets a few hours of sun every day (where I live the sun is pretty reliable), which keeps the batteries topped off and ready to go whenever needed.

And for those of you wondering, the electric motor draws up to 20 Amps, and the 1.2+ Amps added by the solar panels do not make it go faster, since the 1.2 amps are routed through the controller and only serve to charge the batteries. The motor speed controller does not see this extra Amperage, and outputs just the same as without panels, except the batteries will stay charged slightly longer, (extending your range) with the net drain being (20-1.2)A= 18.8A rather than 20A without the panels. The motor only pulls 20 Amps when taking off though, so the draw is much less when at cruising speed. The motor speed controller cuts the voltage off at 32V to keep the batteries from going below 10.5V, but I monitor the voltage and try not to discharge the batteries below 36V.

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wilmadan says: Dec 6, 2010. 5:39 AM
the idea here is to use the power of the sun to power the bike,if we could make a much better design ,well we will all benefited....thanks for the idea mr. dpearce 1...
ronaldino says: Jul 21, 2008. 12:03 AM
I'm having trouble with a couple things. 1) Finding Panels like the ones in the demo and 2) Understanding the correlation between Panel Charge output and Battery Voltage/Amp What should I look for when it comes to batteries and Solar Panels. Is it necessary to have 12V batteries with 20A/hour outputs?
dpearce1 (author) in reply to ronaldinoJul 21, 2008. 8:18 AM
Do a search on the goldenmotor.com forum, you can find out anything you need from people who are using this hub motor setup. The 12 volt batteries are necessary to achieve the 36v needed to power the motor, but the capacity rating will determine your range. Some people on the forum use 10 or 12 A/hr batteries, they are lighter and cheaper but will not have as long a range as 20A/hr.
The Panels are made by a brand called Q-cell, I got them off Ebay, but in general, you should not have to pay more than 3 or 4 dollars per watt.

As for panel / battery voltage / amperage, the requirement of your panels is determined by your battery voltage. If you have a 36v battery, (or 3 - 12v batteries in series), you need a solar panel (or panels) that will be able to charge these batteries using the nominal voltage rating of the panels. For example:
A 12 volt battery charges at around 13.8V, with 12v being the nominal voltage. Now with 3 of these in series, gives you 36 volts nominal and around
42.4 volts needed to charge the battery/batteries. This means you need a solar panel or solar panels that will give you at least 42.4v nominal. A little higher voltage output from the panels is desired since the nominal rating is given for high noon on a sunny day, and you don't want your batteries charging from only 12:00pm to 12:01pm. So a panel with a little higher voltage
will be fine, since it will give the needed output voltage to charge the batteries throughout the day rather than only during a short time when the solar output is greatest. It is the solar charge converters job to regulate this varying voltage coming from the panels, so even if your panels are making up to 100v it will still charge your batteries at the proper charging voltage.

Check out the forum, if you search around on there you can find answers to any questions you might have regarding the electric motor kit / battery setups.
Thanks- David
golden motor forum
Timothy Wooi in reply to dpearce1Feb 28, 2010. 12:05 PM
Check out facebook  timothywooi@gmail.com  or go to m hub pages on Homebuilt electric assisted tricycle for my dual power electric assisted tricycle & a homebuilt Timmy Green Delta Recumbent with 0 footprints to address issues of  Global Warming.
My dual power assisted Electric tricycle from upgrown bicycle and houshold parts
This is my lean dual powered tricycle, made of parts available at home right from used computer chair to a salvaged kid's outgrown bicycle.
It is designed with a choice of 3 power modes,human, combination of human & Electric power and ful Electrical, all can be individually selected to suit personal preference. 1.Manual mode:Pedal cycling for muscles toning up & burning of waste colestrol! (2 motors switched off). 2.Electric assisted mode: For light exer-cycling & climbing hills or low speed cruising (1 motor switch on ). 3.Full Electric power for high speed riding at 24 km/hr! (both motors switched on). This Tricycle is equiped with Amp meter,Volt meter and protected by a resettable 15Amp NFB(no fuse breaker that also acts as a switch). The Amp & Volt meter shows current battery condition and available power.
A solar panel can be built into the fairing to charge the 3 units 12 volts,7AH Computer UPS gel battery! while parked in the daylight as an upgrade modification. Sorry Im unable to attached the free plans & detail progress photos as it was all destroyed through a flood that hit my place in 2006!

Cheers,.
timothywooi@gmail.com
ronaldino in reply to dpearce1Jul 21, 2008. 1:08 PM
I really want to solarize my trike for Burningman this year. Last year I modified the trike to fit two people by building a wooden box with a padded top and mounted it to the back. I also added a shadey rooftop with pvc & canvas but they didn't hold up to the wind at all. My thought for this year is to modify it with solar panels as the rooftop with a frame built out of angle iron from old bedframes that attaches to the frame of the bike. The frame will be tall enough that two people can comfortably sit on the trike with a solar roof that acts as shade while charging up the battery pack that will most likely be positioned inside the Box/passenger seat. Is this a crazy idea? The winds out there are intense so I think I'd have to be able to take the panels off the top to prevent the whole thing from tipping over and remove them at night too since they won't be charging the batteries. I really want to make this idea come to life and I could use a good deal of advice from the forum. I've included pictures of the two of us on the trike and a picture of the trike with it's canvas shade "roof top" Any opinions rear vs. front? What are your thoughts on the added weight load of an extra person? Anyone's input on this idea would be very much appreciated... Thanks
bstevens in reply to ronaldinoFeb 28, 2010. 10:09 AM
Having been to BRC seven times I think relying on something over your head is kinda scary...

Ideally you could setup a solar charging station at camp, and have two sets of batteries.  Make them easily come out and connect to the bike and the charging station.  Then you'd have more range at night :)  Don't forget to include enough power to light it up!

Now I want one.

awang8 in reply to ronaldinoJan 20, 2009. 10:56 PM
you don't need to take the panels off at night. All you need id a prodection diode to stopthe batteries returning the power.
Dr.Bill in reply to awang8Jan 12, 2012. 4:44 PM
Or a cut off switch~
fma321 in reply to ronaldinoAug 9, 2008. 12:31 PM
you ever think of trying wind power at burning man? Try a vertical wind generator. Make your weakness you strength.
Mr.Hambone in reply to fma321Feb 28, 2010. 5:35 PM
A wind generator would be fine, just do as bstevens suggests and carry a spare set of batteries. The generator could stay at base camp charging batteries while the first set is running the bike around.
Timothy Wooi in reply to Mr.HamboneFeb 28, 2010. 11:15 PM
You can consider rewinding a Sturmy archer dynamohub to produce a voltage about 20% higher than your batteries total voltages and use a switch to turn on the dynamofir charging  when down hilling or during braking (connected with the brake through a switch)
You need to rectify the AC from the dynamo to DC using a bridge rectifer,a typical 3Amp 100V PIV will suffice.
A typical 0.7 Volt will be loss after rectification and that is why you need at least 20% higher AC voltage to compensate conversion loss.r

Harnessing & regenerative collection of Energy,
timothywooi@gmail.com
static in reply to Timothy WooiMar 1, 2010. 12:52 AM
The author here pointed to a source for a regenerative braking controller
solarbipolar in reply to fma321Sep 16, 2009. 10:11 AM
Bad idea. Won't work. Just think of the drag a prop would add to the bike when moving. Would destroy efficiency.
dpearce1 (author) in reply to ronaldinoJul 22, 2008. 9:17 AM
That sounds like it would be fun. My advice would be to keep it as light weight as possible, without compromising durability of course. Make sure the trike will hold up to the weight of your passenger + batteries. Since you are hauling two people you cannot afford to add too much more weight to the vehicle, so keep to the bare necessities. You might also consider using a front hub motor with a smaller wheel, like a 20", to give you more torque, but lower top speed.
registerpal says: Jun 11, 2008. 8:05 PM
Can I use only one panel?
dpearce1 (author) in reply to registerpalJul 18, 2008. 7:15 PM
If it is large enough to supply the power you need, and at the right voltage for your battery setup you can. A Solar panel is just an array of solar cells, wired in series / parallel to achieve a desired output voltage / amperage, but obviously the power is limited to the size of the panel. Just one of these particular panels would not do anything for you, unless your power source was around 12v.
TFrosty in reply to dpearce1Dec 22, 2008. 2:01 PM
I live in the area. Where did you get your batteries?
dpearce1 (author) in reply to TFrostyDec 23, 2008. 8:03 AM
Earls industrial liquidators, 14611Hawthorne blvd, Hawthorne, Ca
slapoutz in reply to dpearce1Sep 22, 2008. 5:45 PM
by the way could you add charge things to the back wheels like what the guy said about the pedals but with the wheels would be better =p