Introduction: Solar Powered Trike

Picture of Solar Powered Trike

Travel for free with the power of the sun!

How to build a Solar Powered Trike

The purpose of this project is to build a vehicle that:

-Provides free, 'green' transportation for short distances (<10 miles), thus it must never
plug into a wall socket, or emit any pollutants.

-Charges while at work

-Is cheap, simple, and low maintenance.

-Draws attention to the practical application of green energies, and promotes Fossil Fuel alternatives.

-Reduces excess automobile wear and pollution from cold driving / short, in town trips.

-This is a is a project for Dr. Reza Toosi's 'Energy and the Environment, a global perspective' class at California State University, Long Beach. We look at the sources, technologies, and impacts of energy on our environment.

Link to other class projects, some of Dr. Toosi's ENG-302i lectures, and other interesting videos.

Short video:

Step 1: Acquire a Vehicle

Picture of Acquire a Vehicle

Find a lightweight vehicle with low rolling resistance. A two, three or four wheeler will do, depending on how much work you want to do, but the concept is the same. Four wheeled vehicles may be regulated under different laws. Of course the best vehicle is one that you already have, if you happen to have a three or four wheeled pedal powered vehicle. In the interest of simplicity, a three wheeler was chosen for my project. This Schwinn Meridian Trike was $250 new, readily available locally, and the basket provides a convenient location for batteries and solar panels with minimal fabrication.

The first thing to be done was completely disassemble the trike and paint it a bright 'fern' green. This step may not be necessary, but I felt that it was in my case since this is a school project that is supposed to grab your attention, and let you know that it is a true green vehicle. It is a vehicle that does not use gas, and does not plug in to a wall socket, which would defeat the purpose since electricity from the grid likely comes from a non-renewable energy source. It runs on pure solar energy.

Before painting the frame, I used this stage as an opportunity to reinforce the frame where the Batteries were going to mount. Lead acid Batteries are heavy, but they are relatively cheap.
One tube was welded in to distribute the load over 4 points on the axle carrier instead of two.
It also ties the rear sub-frame together, which makes the tube the load bearer rather than the weld beads, which may eventually fatigue and fail.

High pressure (65psi) tubes were equipped and the Trike was meticulously assembled in order to minimize rolling resistance.

While the welder was out a battery mount was fabricated, and bolts welded to the basket to be used as battery mount studs making removal easier. 12 volt LED's were put in the reflectors and wired as brake lights through the brake levers that cut the motor when you brake. They are wired through only one of the three 12 volt batteries.

Step 2: Drivetrain / Running Gear

Picture of Drivetrain / Running Gear

The drivetrain consists of your electrical system and electric motor. The Electric Hub Motor kit was purchased from (, costs $259 and consists of a front wheel with an integrated brushless 36 Volt electric motor as part of the hub, along with the necessary components such as a twist grip throttle, brake levers that are wired to cut power to the motor, battery level indicator, and the motor-speed controller, 36V battery charger and a battery pack connector. Not sure if the kit is still available but they still sell everything needed. The customer service is basically an owners forum, which did prove useful in diagnosing a bent pin in on of the electrical connections.

The motor install requires a simple front wheel change, and routing the wires back to the controller which will be mounted under the rear basket. Slack must be left in the wires around the steering tube / fork juncture so they will not be in tension even at the maximum steering angle. The grips and brake levers are replaced with the new ones, and their wires also routed back to the controller.

Choosing the right battery is a compromise between price, weight, and range vs. charge time. Lots of money can be spent on batteries, but since I was on a budget, I had to take what I could get. I took a multi-meter to a local industrial liquidation warehouse and found 3 batteries for $20 each, and have worked good so far. (3) -12 volt, 20 Amp/hour batteries are run in series to make 36 volts. 20A/hr provides long range, with the trade-off being a longer charge time. Abattery cut of switch was added so the rider does not have to unplug the battery pack to shut the electrical system off.

Step 3: Charging System / Solar Panels

Picture of 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, 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.

Step 4: Solar Panel Mounts

Picture of Solar Panel Mounts

Now you have to figure out how your going to mount the panels on your vehicle. Hinges were welded on the baskets to mount the panels and allow them to tilt for access to the basket, with rubber hold-downs on the other side to keep them from opening while riding.

Once your wires are all routed and zip tied, your batteries and panels held securely down, double check every thing and you are ready to go.

This Solar Powered Trike does about 15-18 mph depending on the weight of the rider. The furthest I have gone is a little over 10 miles with small hills and little pedaling, and the battery meter still read full (green) at the end of the trips.

At ten miles, the voltage drops to around 36V, safely above the controller's cut-off voltage. If the batteries are kept from discharging too low the panels take about the same amount of time as the plug in charger, since both the plug in charger and the solar charge controller charge with constant wattage. With constant wattage charging, Power, (P), and Ohm's law again (P=V*I), the charging current goes down as the voltage goes up, as the batteries near their fully charged state.

What this means is if you keep the voltage from dropping too low, the panels provide adequate current to match the charging speed of the plug-in charger, but if it drops below a certain point the panels are slower at charging. This is easily avoided since my typical trip range is around 3 miles or less, semi daily at most, so low voltage not an issue, but on longer trips I bring the multi-meter.

Cost Breakdown:
The Trike cost a little over $910 to build

Schwinn Meridian Trike

Q-cell Mono-crystalline Solar panels:

Charge Controller:
$ 95.00

Electric Hub Motor Kit
$260.00 also sells regenerative braking motor speed controllers

$ 60.00 Earl's industrial liquidation, Hawthorne, CA

High pressure tubes $ 15.00 Any bicycle store

Total $910.00

Other solar trikes / information

The last picture is a scan of a page straight out of Dr Reza Toossi's book,
Energy and the Environment, Sources, Technologies, and Impacts.

Book information / purchase


canno (author)2009-03-28

would adding on a wind turbine sort of thing work, as you move the air pushes on the turbine great idea not very original though is there a way to collect some energy from the wheels while they spin using magnets to add to more energy gain. 4/5

kent1956 (author)canno2009-04-19

As mcpguru said you can't power the bike by a wind generator while it is running. BUT, you could have the wind generator working while the bike is parked to help recharge the batteries. This would work if you are in a windy enough area. But any wind would help. You would have to consider the added weight of the generator, because you would have to move it with the bike, unless you just had it mounted at home, or work to plug into your bike. Kent Secor In Cape Coral, FL USA

venkboy (author)kent19562009-06-08

They (the magnets) would slow down the wheels, yes, but you can always use them when you want the wheels to slow down, such as while applying breaks, it will not be a permanent source of energy, but some source. This idea isn.t riginal either though

owatson (author)venkboy2016-05-09

it's called regenerative braking. It's used by many electric cars.

Sprongll (author)canno2009-05-16

You could always use a regenerative breaking system, like the one sold from the same website as the hub motor was brought from.
They would only work when breaking, or coasting down hill, but they would give you a boost to the battery life.

solarbipolar (author)Sprongll2009-09-24

Don't you mean "braking"?

Shagglepuff (author)solarbipolar2009-12-13

 Hey, that could maybe be a good concept- when you hit a wall at 30+, it recharges the batteries! Sure, you'll break every bone in your body, but you'll have added a bit of power to the cells!

velcro2 (author)canno2009-04-23

Canno: I think you're on to something with your comment. If the magnets were in counter position on each side of the wheel, wouldn't the steel spokes break the magnetic field and produce electrical current??? Surely someone has thought of this already but what if.....? I get a kick out of these experts who continue to say "there's no free lunch in science" but there are many energy sources that are FREE already, e.g., the sun's heat and light energy for one.

TwistedmindZ (author)velcro22009-11-01

i think main problem with a generator is that it would be taking energy out of the system. Lets say you are going 30 mph and have a generator going...if you want to get any kinda of useful current out of the generator it's going to cause your setup to slow down therefore converting mechanical energy into electrical energy also take into account resistance in the wire/batteries causing loses due to heat, also any inefficiency in the motor anytime you have heat even small amounts it's all wasted energy. so no, "there's no free lunch in science"

iti (author)velcro22009-10-14

I cant resist.  There are trade-offs with the suns energy too, likegetting too hot, or the fact that the sun 'digests' materials here onearth (just had to replace the little skylight/vent top in the rv). ;).

ben_k (author)velcro22009-04-26

You can't do that, because the magnets would cause more resistance to the spinning wheel because of their attraction to the metal, so you still lose more energy than you generate.

solarbipolar (author)canno2009-09-24

ha, the wind hitting the turbine would just add more drag to it and use more voltage.

all_athlete11 (author)canno2009-04-23

A better idea to get more power from the existing set-up would be to have a way to pivot the solar panel so that is perpendicular to the sun. This would take a minimum weight and would provide substantially more power to the battery. This would mean faster charging time.

mcpguru (author)canno2009-04-02

Sorry - no free lunch on energy, so the magnets would pull more energy out of the system than they put back in (unless you had a perfect system, then it would break even). The wind turbine might work to the the extent the wind is from nature, not the movement of the bike -- again, no free lunch on energy -- but if you were going to do that, just put up a sail and skip the weight and translation of kinetic to chemical to electric to kinetic.

denise981 (author)2016-05-03

I am so not mechanically inclined so maybe this is a stupid question. Would it be possible to make this so when pedaling the bike helps to build up the charge in the batteries and would it be possible to use the electric motor as a pedal assist rather than for full power?

owatson (author)denise9812016-05-09

This would make it harder to pedal and you wouldn't get any net gain. You could have a generator that you attach to the wheels to slow down instead of brakes. This is called regenerative braking and is used on many electric cars.

denise981 (author)denise9812016-05-03

I ask this because I have a bad ankle and knee. I have an electric bike which I love but a trike would be fabulous for grocery store runs, etc. I pedal my electric bike (good exercise!) and use the pedal assist mode or full electric power on hills and inclines.

Johenix (author)2010-02-28

Thanks for alerting me to the Schwinn Meridian. Cool even without solar power.
As an alternative I might look at the old 80cc 0.01Hp "Chicken Power" two cycle motor from the 1970-80's.
What really bugs me is the power wheel uses 36V (rather than 12V) and you must use multiple 12V panels and batteries (adding excessive weight).
Does anyone make lower voltage wheel motors or higher voltage solar panels?

lukeyj15 (author)Johenix2010-09-19

the only problem is that to get the same amount of watts (energy) at a lower voltage, current (amps) increases, so you need 3 12v batteries in parallel instead of series. You also need wire that is 3 times thicker.

owatson (author)lukeyj152016-05-09

it's not 3 times thicker, it's 3 times cross-sectional area

astral_mage (author)Johenix2014-01-23

check out or 4 the parts u need?

3967 (author)2016-05-03

aren't there any legal problems ?

JackC21 (author)39672016-05-04

Every state and country has laws about electric bikes. In PA. US. You can not go over 20 mph. In the UK you must use pedal assist and not a throttle.

denise981 (author)2016-05-03

I am so not mechanically inclined so maybe this is a stupid question. Would it be possible to make this so when pedaling the bike helps to build up the charge in the batteries and would it be possible to use the electric motor as a pedal assist rather than for full power?

Waltervp (author)2016-05-03

I have Cystic Fibrosis and love the electric bikes as i just cant get up any hill/ramp without help. I cycled across SE Asia and Australia on electric bikes and would love a solar equipped one! In fact cycling from lake Eyre to mount Kosciuszko in sept 2016 for a documentary... if anyone wants me to trial a fatty elec solar bike..... i will see power every 2 or 3 days and can rode with L assist (100W). STILL LOOKING FOR SPONSORS!

adsandy (author)2010-08-11

Wouldn't it be easier to just pedal?

Climber333 (author)adsandy2011-08-10

Unless you're disabled, which adds a whole new dimension, doesn't it? Thanks again people for thinking outside your own tiny box.

adsandy (author)Climber3332011-08-11

Well then, how does the disabled person get on and off? What if it malfunctions during the ride? How is a disabled person to construct one?

Climber333 (author)adsandy2011-08-11

Would you like to know the range of disabilities a person can have or are you asking me personally...perhaps you're offering to help. A one-handed person could do all those auto-immune disease...Chronic Fatigue Syndrome...Fibromyalgia....Lyme disease. Perhaps a 20 second period of thinking before you ask.

adsandy (author)Climber3332011-08-11

Most of the people with those diseases could peddle. Those with severe pain are most likely already medicated. Someone with that severe of pain would be smart to choose something professionally made rather than this homemade thing. They would need something reliable. I honestly believe that this is an impractical vehicle for disabled people. I'd appreciate it if you could offer criticism without insulting me.

astral_mage (author)adsandy2014-01-23

but there are studies that are showing. the use of pedal bike can an do reduce the pain.

Waltervp (author)astral_mage2016-05-03

I have Cystic Fibrosis and love the electric bikes as i just cant get up any hill/ramp without help. I cycled across SE Asia and Australia on electric bikes and would love a solar equipped one! In fact cycling from lake Eyre to mount Kosciuszko in sept 2016 for a documentary... if anyone wants me to trial a fatty elec solar bike..... i will see power every 2 or 3 days and can rode with L assist (100W).

Ryoushadow (author)adsandy2014-06-21

You're seriously asking what use a disabled person has for an electric bi/tricycle?

Please, think for a minute. If you can't come up with anything I'll do my best to hide my frustration as a physically disabled person and explain.

Dr.Bill (author)adsandy2012-01-12

Hey this would be good for me as I have arthritis ! I am not "Medicated" as I do not like the side effects. I can peddle for some distance and would not mind having something like this. A Motorized Chair to me just makes me more sedentary and prone to worse diseases, like diabetes.
Being a couch potato is not my idea of having a life and this trike would make my life worth living. Thank You dpearce1 for posting this I'ble.

Climber333 (author)adsandy2011-08-14

And I'd appreciate it if you'd try to give disabled people the credibility they deserve. Sarcasm toward your questions was well deserved, given the lack of critical thinking necessary to make them possible.
Where are you getting your information about what people with the diseases I mentioned are capable of? Are you inventing it? I am on Trazadone and Morphine and it doesn't manage my pain....if I push too hard, I end up setting myself back weeks or months or going into a full relapse, so pedaling is not always possible .
My history is one of being an Olympic caliber athlete with a range of skills from building computers to being a certified arborist. There's little I cannot do, given the tools and time and I can assure you, I make things better than you can buy (if you have the money to buy off the shelf).
You can't fit all disabled people into the same box, so just decide if it's practical for yourself and let others decide for themselves.

Waltervp (author)Climber3332016-05-03

I have Cystic Fibrosis and love the electric bikes as i just cant get up any hill/ramp without help. I cycled across SE Asia and Australia on electric bikes and would love a solar equipped one! In fact cycling from lake Eyre to mount Kosciuszko in sept 2016 for a documentary... if anyone wants me to trial a fatty elec solar bike..... i will see power every 2 or 3 days and can rode with L assist (100W).

lawrence.rhodes.3 (author)2015-07-26

Here is what the big brother did at the 2013 World Solar Challenge. Stella Lux for the 2015 challenge is even better. These are 4 passenger vehicles.

220754861 (author)2015-06-10


Congratulations for the project.

I want to do the same with my recumbente trike but i´m putting the pannels in the top of the trike. But since my solar pannels are 22v 0,5amps i associate 2 to have 44v 0,5v and another set of two to reach 44v 1 amp, so total of 4 solar pannels.

I connected a rectifying bridge with a capacitor to have stable current, and that makes the maximum voltage of around 43v and the minimum of 40v.

I connected a battery of 36v 2ah and it did recharge it, but now i order one 36v 15ah ebike battery and i´m hopping it will recharge. My only doubt is that if a current between 0,5 - 1 amp is enough to start recharging a 15ah battery. Because if that work i wont need any MPPT RIGHT?

The secrect, i think, is to associate solar pannels to not exceed 44v then we will have a much easy system without any chargers, my only doubt is if a small current can charge the battery. If yes that is the best way of charging because a small current means the battery will last more.


daenergymon (author)2015-05-05

Well done. My friend built a canopy over his to put the solar panels on

NRG4UandMe (author)2014-12-07

it would be a very valuable addition to have plug in capability for 'extra range' - not too much cost and or battery would thank you on cloudy days, extra heavy loads and unplanned extra distances and speeds ....

MbConcertina (author)2014-10-07

I know some adults with disabilities and some seniors who are capable of building and peddling, and would be appreciative of having solar power as an alternative so they could take longer jaunts

solarbipolar (author)2009-09-24

All you people need to realize that those solar panels could take as much as a week or longer to recharge the batteries. A good example is a cordless rechargeable lawn mower. They use an almost identical setup - 24v motor and two 12v batteries. One mower manufacturer sells a solar panel as an option and tell you up front that it will take at least 3 days if in full sun. But you can't keep the panels always pointed at the sun without a tracker. Most of the cheaper solar panels are nothing but trickle chargers that just keep batteries topped off like on RVs or other vehicles that have a lot of accessories that drain a battery even if not being used. And no, you can't ride down the road perpetually with sun power and no batteries. It's just common sense. There are experimental solar cars that have competitions, but they have huge arrays of solar cells and use flat terrain and hug the ground and are streamlined.

So the system isn't perfect. I'm not either but I get by.

I think this is one of the BEST instructables I've ever seen.

And it raises a LOT of questions in my mind. How would it do with higher efficiency panels? Or high tech batteries? Is there a way to get regenerative energy BACK into the panels when you are going downhill? This Instructable is 6 years old now. I'd LOVE to see someone that is smart about electronics & bikes tackle an update to this.

cnathan (author)solarbipolar2013-09-23

You have such negative comments. Where is your Instructables at?? This Instructable is AWESOME!!

mbucy (author)solarbipolar2013-05-27

I have a Black & Decker cordless electric lawn mower also. There are numerous nay sayers that can say how things cannot/or should not be done. Make a constructive criticizim solution part of your suggestion. This is a well done Instructable that hopefully challenges others to see how they may improve it. It sparks interest and challenges others to come up with a better way- Stay positive. No matter what country you live in, stockpile "stuff" for inventing. :)

lloydrmc (author)solarbipolar2012-05-07

We don't need to "realize" any such thing. He presented the math and the limitations of the system, and his numbers add up. He's not deep charging the battery, but rather topping it off.

cricket3_2000 (author)2010-04-25

I thought the spokes and wheel of the bikes were made out of sturdy aluminum. Are they?

noo its either steel or stainless steel. aluminum wouldnt handle the stress at all.

Kris T. (author)2013-06-10

I have no knowledge on anything solar or batteries, therefore please forgive my question if it sounds really "stoopid."

Would it be possible to combine some sort of crank/wind up power (similar to those camping/emergency flashlights) via the pedals and chain in addition to the solar, for a little extra power on cloudy days or evenings?

Kris T. (author)Kris T.2013-06-10

Also meant to say: "Really love your idea!" I guess typing late at night doesn't benefit one very well.

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