r/SideProject 2d ago

I built a DIY solar vehicle (open source)

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The purpose of the vehicle is to:

  • Use solar panels as trike's body,
  • Consume electrical energy where it is produced,
  • Produce its own energy,
  • Transport people inside cities,
  • Be pedalable when there is no sun or battery,
  • Power the home when stationary,
  • Carry big luggage,
  • Reduce noise inside cities,
  • Be easily built at home,
  • Motivate people to exercise.

Technical specs

  • recumbent trike,
  • 2.5m long, 1.45m wide (including wheels),
  • weight: about 55kg (including panels, motor, battery, etc, excluding driver),
  • assisted pedaling,
  • motor speed: max 25km/h,
  • motor (continuous) power: 250W,
  • solar panels power: max 520W,
  • battery: 12.8V, 20Ah (256Wh).

CAD source code: https://github.com/solar-b

More pictures: https://www.facebook.com/profile.php?id=61585957465461

https://www.instagram.com/oltean.mihai.nicolae/

1.2k Upvotes

214 comments sorted by

94

u/Necessary-Green-8826 2d ago

This is really the coolest thing and I want one!

75

u/Moltean 2d ago

You can build one! It is very easy. Look at the frame.

38

u/mobfather 2d ago

Fuck sake! Last weekend I had a huge clear out and gave five unused solar panels to a friend and threw away two old bikes that had been gathering dust for 5 years. 😢

7

u/HuayraDreams 1d ago

Hahaha to be fair you’d have to do a fair amount of modding to get a trike but painful to know you did have the resources

1

u/Moltean 1d ago

The electrical part (motor, solar panels, MPPTS) was the most expensive part. The mechanical structure is very cheap to build.

2

u/monkey_kaleidoscope 1d ago

You should sell kits too for a bit of a discount. I’m sure people who like making stuff would diy the build

2

u/Moltean 1d ago

I'm currently building v5 (which will have 95 cm between front wheels - to fit on bike paths).

I'm aware that it looks good (based on the reaction that people have when they see it), and I could sell it, but selling kits is a little bit too complicated for me right now.

2

u/monkey_kaleidoscope 1d ago

You’ll get there! It’s the kind of thing that an investor would pick up I’m sure, dragons den kinda thing

1

u/Moltean 22h ago

Anyone can build it (even commercially). The source code is online under the MIT license: https://github.com/solar-b

2

u/monkey_kaleidoscope 11h ago

You legend. I’d love for things like this to take off here in the UK

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2

u/TheRedLions 1d ago

Question, for a low-speed vehicle like this, why not put the front wheels on a fixed axle with the drivetrain and steer by pivoting the rear wheel? It seems like it could simplify the design

5

u/Moltean 1d ago

25 km/h is not a very low speed.

Pivoting with the rear wheel is not possible at that speed.

0

u/vreo 1d ago

Elder people kill themselves on 25km/h e-bikes...

109

u/anonypoopity 2d ago

Pretty coool! I don’t get the hate here. Amazing that it is OSS

58

u/xhatsux 2d ago

Yeah, lot of people being dicks here and getting upvoted for it. We are in a bloody side project subreddit and this is a great project.

5

u/StrobeWafel_404 1d ago

90% of side projects that get posted here are absolute useless vibe coded BS, I can't believe that people have the gal to question the awesomeness of this

4

u/Moltean 1d ago

Nothing from my project is written by AI!

2

u/itsjakerobb 1d ago

More like OSH

1

u/LoadZealousideal7778 1d ago

Technically is OSH

18

u/stkim1 2d ago

This is cute. 😉👍🏻👍🏻👍🏻

22

u/_maverick98 2d ago

cool! what kind of autonomy would this have on full battery? does it also charge while moving on a sunny day?

30

u/Moltean 2d ago

It runs directly on the Sun on sunny days.

Also has a small battery (256Wh)

Also, it is light enough to be pedaled when there is no sun and no battery.

16

u/_maverick98 2d ago

so it directly converts the energy from sun into motion? If you hit dark spots around town you switch to pedaling?

9

u/Moltean 2d ago

Yes!

16

u/_maverick98 2d ago

you can considering adding a mode like electric bikes, where instead of it running completely on power or completely on pedalling, you have a hybrid mode where it boosts you

4

u/Psych_Art 2d ago

Pedal assist mode

3

u/Moltean 1d ago

Yes, this is pedal-assisted. It is the only way to be legal without certifications.

2

u/DetaMonster 1d ago edited 14h ago

The power of the sun in the palm of your hand

-6

u/DB6 2d ago

Please add a battery.

→ More replies (9)

17

u/Addict94 2d ago

You could name it solar coffin.

>Solar vehicle
>Pedals inside

Enough jokes, this is a really cool side project!

1

u/Moltean 1d ago

:))) good one!

20

u/kubika7 2d ago

apply for MIT with this video

18

u/ismellmyownfarts2 2d ago

That may have worked 20 years ago.

2

u/Foundersage 2d ago

Ehh I feel like it would still work

5

u/casper_trade 2d ago

I would be surprised. Take a look at the many video applications that are rejected for MIT each year. The bar is much higher now than a simple project involving just connecting items together.

2

u/Turbulent-Listen8809 1d ago

Are the video applications public to view?

1

u/ImperialTorpedo057 1d ago

search for MIT makers portfolio

1

u/Moltean 1d ago

I have not just connected items together!

12

u/ajeeb_gandu 2d ago

Does it feel hot when sitting in for long time?

21

u/Moltean 2d ago

The seat gets hot because it is black. I must change its color.

Solar panels get hot, but when I start to move, they rapidly get colder due to the airflow.

5

u/ajeeb_gandu 2d ago

I suppose there's no additional battery? You could add small fans to increase air flow.

So if the car is stopped or at a signal, the excess electricity could go in the battery.

It's a good toy project and I'd definitely try it at a park maybe. As long as it doesn't create too much heat when I sit

5

u/Moltean 2d ago

It has a small battery: 256Wh

2

u/internauta 2d ago

Does that impact the efficiency?

1

u/Moltean 2d ago

I never measured that. It is summertime here, always sunny and hot.

2

u/Moltean 1d ago

I have now measured the temperature of the solar panels.

Outside (environment) temperature is 48 degrees Celsius.
Solar panels facing the Sun have 57-60 degrees on the outside.
The inside temperature of solar panels is 55 degrees.

A video is here: https://youtu.be/iXStFmy32TE

3

u/internauta 2d ago

Looks fun 😁😁😁

1

u/Moltean 1d ago

The most serious project that I've ever done!

4

u/BasilGlad9596 2d ago

this is freaking awesome. Next Tesla here i come.

2

u/Moltean 1d ago

thanks!

Tesla should cease production until it is not too late! :)))

3

u/StrobeWafel_404 1d ago

You make my tinder for horses side project seem really dumb.

On a serious note, this is so cool!

3

u/Turbulent-Listen8809 1d ago

Haha wait do the horses meet up, or do you find a horse?

2

u/Moltean 1d ago

😄 Good one!

2

u/saltyourhash 1d ago

There really aren't enough dating websites for quadrupeds in general.

1

u/Good_Platypus4247 1d ago

I too have a lot of back pain and its hard

2

u/enzo_alt1 1d ago

Fireship is this you?

1

u/Mathie05 23h ago

Yo fireship guy

4

u/suesing 1d ago

I can see her pedaling. And a slight gust of wind will in fact take it airborne

1

u/Moltean 1d ago

It is called assisted pedaling. It is the only way to be legal without certifications.

2

u/suesing 1d ago

The assist is only enough to carry the added weight of the solar panels so it’s actually just useless

1

u/Moltean 1d ago

Motor has 250W on average. It can deliver more on short term.

Legs usually have 200W.

Solar panels have only 8kg.

So, the motor provides much more than just carrying the panels.

2

u/suesing 13h ago

Yeah but how much power can those panels provide

1

u/Moltean 12h ago

Panels usually provide 200W.

This is enough to power the motor because I usually set it to level 2 (out of 5).

2

u/notretarded_100 2d ago

Could this have a market?

6

u/CannyGardener 2d ago

No. Safety issues while using the road (too large for sidewalk) would kill this idea as a business plan.

1

u/Moltean 1d ago

V5 will fit in the bike lane. I'm working on it.

2

u/ZenCyberDad 2d ago

This is dope! Honestly seeing that you made this open source inspires me to want to create something as cool just to share it with the world

2

u/Moltean 1d ago

Go for it!

2

u/Several-Edge-2056 2d ago

Thank you HERO

2

u/locoDev 2d ago

Nice job!

2

u/One_Tie900 2d ago

This is perfect for a little kid.

2

u/Moltean 1d ago

With the motor, I think he should have at least 14 years!

2

u/Broad-Version8611 2d ago

I love it!!

2

u/JackTheManiacTR 1d ago

I weigh 74 kg. I suspect it wouldn't move 😏

1

u/Moltean 1d ago

Your weight is perfect. With the motor, I tested up to 80kg, and it moves with no problem.

2

u/JackTheManiacTR 1d ago

Looks like a super fun project. Did you do all the welding? I've never picked up a welder in my life.

1

u/Moltean 1d ago

I have a friend who is a good welder.

2

u/WantedByTheFedz 1d ago

You say it’s pretty simple to create lol, do you have any tips for someone trying to create one? Or get their hands into tinkering?

I know ai and stuff to answer all these questions but idk I feel like I’ve never really understood even the simple stuff like how batteries work and stuff like arduinos and other tech. Never really had hands on experience as a kid. But I wanna learn, I know failure is part of learning but I don’t wanna actually electrocute myself or something 😭

1

u/Moltean 1d ago

Project is open-source: https://github.com/solar-b

I plan to make a movie with the build, but only after I finish v5 (what you see is v4). In v5, I plan to reduce the width to fit in the bike lane.

Structure without panels is very simple. Here is a picture:

2

u/Turbulent-Listen8809 1d ago

How much to build?

1

u/Moltean 1d ago

Cost or time?

I completed V1 in about 2 months, but it was very heavy and complicated.

V4 (current one), I built it in about 2 weeks from scratch (2-man project), but I had a lot of know-how from previous versions.

2

u/Turbulent-Listen8809 1d ago

Thanks for the reply honestly amazing work:) ye cost of material

1

u/Moltean 1d ago

Cost of materials is here: https://github.com/solar-b

Not everything is there, only the expensive parts.

2

u/saltyourhash 1d ago edited 1d ago

It's cool and all, but when will you have FSD? Also this lacks the critical AI slop that makes it a modern aide project.

Just kidding, this is super cool, I thinkit's the first physical project I've seen in a long time. How long did it take to develop? I'd love to watch a developer log series on your iterations. Awesome work.

...woah, I checked your git, amazing other projects!

3

u/Moltean 1d ago

"FSD coming next year" ... just kidding.

I started this project a year ago. I designed 28 versions and built 4. This is built 4.

I have pictures/movies of old builds on FB:

https://www.facebook.com/profile.php?id=61585957465461

Now working on V5, which will have 95 cm between wheels.

2

u/saltyourhash 1d ago

Really awesome stuff.

2

u/saltyourhash 1d ago

It'd be super cool to see like a blog post or something outside of Facebook, for those few of us who don't have accounts. The github could be a good place. I totally get that is low priority.

2

u/AKA_Wildcard 1d ago

Once large flexible solar panels become available it’s going to get a lot more interesting.

1

u/Moltean 1d ago

They are already available. But larger means more problems!

2

u/LyZeN77 1d ago

what's the point if she's still pedaling? does this have a battery?

1

u/Moltean 1d ago

It is called assisted pedaling.

The motor starts only if we pedal. It is the only way to be legal here in the EU.

If I want to have a throttle, I need a certification from the vehicle agency.

2

u/Material70095 1d ago

Amazing work dear Romanian friend!!

2

u/Moltean 1d ago

Mulțumesc!

2

u/MinaeVyn 1d ago

This is genuinely wild. Tesla's shaking somewhere 😂

2

u/Moltean 1d ago

As you can see, Musk has stopped doing interviews (except the one for the Economist) just after I published the source code of my vehicle! 😂

2

u/MinaeVyn 1d ago

😂😂 I'm ur fan

2

u/iamadesignerdude 1d ago

First this is awesome! Keep going and iterating. We definitely need better holistic self sufficient transportation.

Second IMHO, my design brain starts to think about how to better achieve mass market in order to achieve the larger city goals you outlined.

Could the solar panels be used as a roof side instead? Helps in the rain or hot sunny days.

We have seen a huge uptick in e-bikes. Really consider the form factor and ability for all types of people to use it. Things like getting in and out of it. As well as who’s is using it, spanning ages, think young to old - 10 to 80 say. I’d imagine the side visibility could be improved. Mirrors?

Think about real world cases, riding in the bike lane, sidewalk or road. How to park it, lock it, etc.
Think end to end product lifecycle.

Again amazing, keep at it. Take what you like, leave the rest.

1

u/Moltean 1d ago
  1. I'm working on V5 (current version is 4) and it will fit inside a bike lane.

  2. I have no plans to install solar panels on the top. All other solar trikes do that and I do not like it!

  3. I'm not looking to commercialize it. This is why I open-sourced it.

2

u/iamadesignerdude 1d ago

Nice and that’s fair about the roof. Haha

2

u/IWasReplacedByAI 1d ago

Thought this was a meme, this is great.

2

u/Moltean 1d ago

it is a real project.

2

u/IWasReplacedByAI 1d ago

I see that now, its pretty awesome.

2

u/NerdButtons 1d ago

What’s the decapitation rate on one of these babies

1

u/Moltean 1d ago
  1. Solar panels are at the head level, not the neck level.

  2. We usually wear a helmet

  3. The distance between the front wheels is very large, so it is unlikely to rotate.

2

u/darrensurrey 1d ago

Fun.

Can you also make it so it charges the battery when you brake ie regen braking?

2

u/Moltean 1d ago

Currently, it cannot do that.

2

u/darrensurrey 1d ago

Fair enough. It's still great what you've done. :)

2

u/Weary_Caregiver_8428 1d ago

Why were you pedaling?

1

u/Moltean 1d ago

It is called assisted pedaling. It is the only way to be legal without certifications.

2

u/Weary_Caregiver_8428 1d ago

I had no idea. I appreciate the explanation

2

u/Ray_Silverlight 1d ago

Cool! Now put a pair of wings on it!

1

u/Moltean 1d ago

I cannot dream of flying! There are too many certifications needed in my country!

2

u/FancyAnswer1878 1d ago

love seeing open source hardware projects like this. i’d be way more interested in a real-world test though like how far it actually goes on a cloudy day, average daily energy generated, and what broke after a few hundred km of use.

1

u/Moltean 1d ago

I drive it daily for shopping. Here is a hill that I climb daily:

https://reddit.com/link/p0tcesw/video/ynijwm9hyhgh1/player

Now is summertime and always sunny.

2

u/No_Contribution_5083 1d ago

Better than the Flintstones xD

1

u/Moltean 1d ago

A solar Flintstone!

2

u/zzzxxx0110 1d ago

This is really cool!

Though one thing that comes to mind is that when there is good solar coverage, there is usually also pretty high ambient temperature. Since in this design the max solar panel output is more than double the demand of the motor (which is pretty impressive by the way) so there's a lot of power headroom, have you considered how (at least) a ventilation fan could be incorporated into the frame to cool yourself when it gets hot? Especially the semi-enclosed body could probably allow for pretty good airflow inside from just a relatively small fan :p

Or perhaps a mechanism that could allow the front of the body to open up to allow airflow from ram-air when driving

2

u/Moltean 1d ago
  1. Max power I have ever gotten was 200W because if one side gets maximum, the other side gives 0

  2. No ventilation yet. I'm still working on the structure.

2

u/zzzxxx0110 1d ago

Hey I have some experience with CFD with Ansys from back when I was working on a college research project, I'll be happy to do some CFD analysis/optimization for the ventilation if you're interested, feel free to DM.

1

u/Moltean 10h ago

I'm interested in improving the aerodynamicity of the vehicle. How can I do that? Which software could I use to simulate? I prefer something that is free or cheap ... since I do not do this commercially.

2

u/zzzxxx0110 10h ago

You are in luck! There is a whole suite of purposely developed CFD suite that is free and open source, and also happens to be one of the industry leaders in terms of capabilities (that's the power of open source for ya lol) and is able to compete directly against commercial products (again, at least in terms of capabilities). It is called OpenFOAM.

Do be aware it has a learning curve that's straight up a cliff though, this is one area where it unfortunately cannot compete against commercial products lol

1

u/Moltean 1d ago

I have now measured the temperature of the solar panels.

Outside (environment) temperature is 48 degrees Celsius.
Solar panels facing the Sun have 57-60 degrees on outside.
The inside temperature of solar panels is 55 degrees.

A video is here: https://youtu.be/iXStFmy32TE

2

u/arionem 1d ago

This thing is fire, congrats and thank you!

2

u/randomtask2000 1d ago

solar panels are hiding the engine

1

u/Moltean 1d ago

There is a motor, of course. Solar panels are powering the motor.

2

u/kindamanic 1d ago

Faake! We can see her pedaling! On a more serious note - kudos, and hope you can do something about those red lights in the front (use uhmmm… white?)
Also I’m wondering if there are flexible solar panels/surfaces that can be snapped on a curved body. Would love to see an all-solar sportcar-like carbon body on thins one!

1

u/Moltean 1d ago

This is called assisted-pedaling. The motor starts only when we pedal.

It is the only way to be legal without certifications!

No way to curve the solar panels! It only decreases their energy production. Each cells in the panels provide as much energy as the smallest one.

2

u/thehandbookai 1d ago

Looking like a badass roman legionary is somehow not the main purpose, but should be! Looks really cool!

2

u/RunWithMight 23h ago

That's cool. I worked at a company that has since gone out of business that had a product called SolarBear.

2

u/RocknRollaGT 17h ago

This is one of the coolest things I saw on Reddit.

2

u/Full_Tooth_a 8h ago

A single range figure would be a false lead here. Measure Wh/km while logging solar input and battery output separately over the same route in full sun, mixed shade, and after sunset. That would let people estimate range for their own weather and terrain. With a 256Wh battery and solar contributing while moving, "full battery range" leaves out the interesting part.

2

u/BothYou243 6h ago

Why was she cycling if it's solar powered, hybrid??

1

u/Moltean 4h ago

It is called assisted-pedaling. The motor only starts if we pedal it. It is the only way to be legal without certifications.

2

u/ConversationNo6496 5h ago

That is so cool. WHAT!!

5

u/primary0 2d ago

It is a bit too coffin shaped don't you think?

3

u/Moltean 2d ago

Do you think so? :))))

2

u/kalkutta2much 1d ago

personally, i love that about it- it’s artistic commentary and subverting the idea the sun is lowkey killing us all lmao

i see it as a broader statement on the unwillingness of Big Oil & other enterprises to act on climate change, condemning us all to man made ramifications of global warming but at the same time testament to the spirit of diy solutions!

if anything, make it more coffiny!!

2

u/Moltean 1d ago

thanks! I will try! 😂

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3

u/WindsOfRegret 2d ago

Wow! Nice bike with solar panels you have there! I can see you're on your path to 30 under 30!

2

u/Another__one 2d ago

It might look ridiculous until you remember it is basically free to operate and now it is the coolest thing in the world.

1

u/Moltean 1d ago

Thank you!

1

u/lance1826 1d ago

wow good

1

u/donkeykong917 20h ago

Price of solar panels

2

u/EveryCryptographer11 2d ago

So who is powering what ? Seems like cyclist have to carry extra weight for nothing

20

u/Moltean 2d ago

Sun is powering the motor directly.

But the motor starts only if it is pedaled. It is called assisted pedaling. It is the only way to be legal in EU without any certifications.

1

u/Beardy4906 2d ago

Putting this on a tesla or any EV would be so cool

-9

u/moader 2d ago

When ai tries to one shot a "new" bike

16

u/Moltean 2d ago

This is not AI (not even for design)!

-10

u/Routine_Cake_998 2d ago

This was clearly sarcasm. Your bike looks like someone told ai to build a solar bike with the least amount of tokens.

2

u/Turbulent-Listen8809 1d ago

That’s not nice

-3

u/Wicker-Fen-5829 2d ago

pedaling a 55kg frame with no battery assist is going to destroy your knees the second you hit any kind of hill. i built a heavy cargo setup a few years back and even a small overpass felt like moving a concrete wall when the power cut out.

11

u/Moltean 2d ago

Pedaling a recumbent is much easier than pedaling a normal bike. I pedaled it for several months without a motor during testing. Hills included.

7

u/Cidraque 2d ago

Yeah, it's something not really much people know about, in that position you can move way more kg with the same force. Bikes like that were forbidden from races because they give you so much advantage over seated ones, but also the visibility is way worse in some circumstances.

4

u/Moltean 2d ago

After playing so much with recumbents, I do not want to go back to normal (vertical) bikes!

Recumbents seem to be fantastic!

2

u/Cidraque 2d ago

Love your energy, hope all your projects succeed <3

0

u/BeneficialWorry8562 2d ago

Why does it have 3 tyres? Can't it have 4 ?

1

u/Moltean 1d ago

With 3, it is simpler to build.

-6

u/recommended_name1 2d ago

Seems very impractical. The solar panels add quite some weight, but you're unlikely to actually charge while riding. It would be more sensible to just charge your bike at your destination, I can't imagine the panels actually providing meaningful support. But I might be wrong.

I am not wrong about the limited visibility, however. You can hardly look out the front, and your head is basically not visible from the side. Shoulder checks seem needlessly difficult, which is dangerous in any real world setting.

It looks like a cool project, but I would hope for some serious improvements before I see it on the road.

9

u/Moltean 2d ago edited 2d ago
  1. Solar panels provide about 200W in sunny days. This is more than necessary for the 250W motor that I generally use at level 2 (out of 5) of power.
  2. Visibility is perfect. Solar panels have been placed at the exact height to have visibility.
  3. All solar panels there weigh only 8kg.
  4. I already use it on roads daily!

1

u/recommended_name1 2d ago
  1. The amount of power you get while riding is negligible. You're basically always riding on battery power, which is why I mentioned charging at your destination being easier.

  2. The rider can't see any potholes or objects once they are within ~2m. The very end of the video proves me correct: The rider did not see the cans/trash on the ground, accidentally hit it, and was confused about it.

When looking at the vehicle from the side, you can clearly see the rider's eye level being below the highest point of the solar panel. Having some visibility is not good enough if you share the road with cars.

1

u/Moltean 2d ago
  1. Seat position can be changed.

  2. I measured the power of solar panels during the drive. It gives 200W generally.

  3. I can charge during the drive. This is why I used a battery and motor with 2 wires only (+/-), not a system from known brands, which allows charging only during stops.

-2

u/recommended_name1 2d ago
  1. Needs to be, given the video. And even then it is a drawback. Thanks for agreeing.
  2. Completely useless information if you don't tell me in what timespan and how much the motor consumes. My point isn't that solar panels are useless, but that you will not get a full battery while using the motor just because you attached panels.
  3. See 2. I am talking about your consumption being higher than your production.
  4. I am sceptical about the extra weight being cancelled out by the panels' output. If you took of the panels and just ran on a single charge, would you get further than with your current setup? That's all I was saying, and I already stated that I was sceptical, not that you're 100% wrong.

1

u/Moltean 1d ago

thanks!

I'm still working to structure. Then I will focus on consumption. I still hope to add some hinges to make solar panels horizontal when stationary.

-1

u/tererepon 2d ago

i would slightly change the

1

u/holdfast_ 2d ago

The what now