The Maxun solarbike project

Solarbike DIY Community

The Maxun One solarbike contributes to increasing awareness that solar energy can fulfill the world's entire energy needs, see: Solar power from the Sahara. Traveling at a speed of 25 km per hour, powered solely by solar energy, this bike continually confronts you with the immense power of the sun.

I want to make this unique experience accessible to a wider audience, and one of the ways to achieve this is through DIY communities. Therefore, I am looking for people who can contribute to setting this up.

Who can help me? 

Solarbike zelfbouw gemeenschap
De Maxun One solarbike draagt bij aan het vergroten van het bewustzijn dat zonne-energie de volledige energiebehoefte van de wereld kan vervullen. Met een snelheid van 25 km per uur, aangedreven door enkel zonne-energie, confronteert deze fiets je telkens weer met de enorme kracht van de zon. Ik wil deze unieke ervaring toegankelijk maken voor een breder publiek en een van de manieren om dit te realiseren is via zelfbouw gemeenschappen. Daarom ben ik op zoek naar mensen die kunnen bijdragen aan het opzetten hiervan. Wie kan helpen?

A lightweight solarbike that drives entirely by solar energy

The first 2-wheel solar bike that drives entirely by solar energy
Lightweight ebike 13kg, with panels 17kg total

Imagine that you can cycle entirely by the sun's power. Until now this was a pie in the sky. But with my invention of the Maxun One solar bike, the impossible has become possible. The solar panels alone deliver the energy for a speed of 25km/h and a distance of more than 100km without pedalling.

Mariya Koptyeva on the Maxun One solar bike 2022

Mariya Koptyeva is riding the solar bike in 2022:

Albert van Dalen is riding the solar bike in Maastricht in 2015:

Solar cycling: a new sport

The solar bike is like a sailboat but uses the sun instead of the wind. People sometimes ask me: why don’t you charge the battery at home with solar energy and then cycle without panels? But you also don’t ask a sailor: why don’t you use an electric boat and then charge the battery at home with a windmill? Similar to sailing, solar cycling embraces a unique sporting challenge: achieving maximum speed by harnessing the power of solar energy. 

Description of the solar bike

The solar bike is made very lightweight, sportive and fast, despite the solar panels it rides almost as light as a road bike. The solar panels are small enough to allow easy riding in traffic, and large enough to perform well, even on a semi-cloudy days. A small battery provides energy in the absence of sunlight. 

Riding by solar energy is a unique experience; we just need sunny summer weather. The solar bike is one of the most remarkable vehicles on the street, nothing compares, no one has ever seen such a thing before. I often hear yelling: what the fuck is that?

The advantage over a normal e-bike is the absence of large batteries; this makes the Maxun One lightweight, just 17kg. Instead of lugging around with heavy batteries, which have to be charged on the go anyway, you can now drive day after day without being dependant on recharging. It is like having a perpetual motion machine!

The development of the solar bike was a technical challenge; all components have to be of the highest level, such as the solar cells, for which a superior, anti reflective, low loss coating had to be developed. Aerospace materials are used to reduce the weight of the whole solar bike to 17kg, but also make it strong enough to withstand stress caused by riding at high speed on bad roads. Furthermore the solar bike remains stable at high speed. 

At the Maxun One solar bike, high tech, beautiful design and usability comes together. Because it is the first solar bike of its kind in the world, it's called the "One". This is my Maxun One solar bike, it is fast and very lightweight, without the need of any trailer: 

Mariya Koptyeva demonstrates the 17kg weight of the the Maxun One solar bike:

Mariya Koptyeva drives away:

See here how easy the panels are mounted:

Solar power from the Sahara

My solar bike has a mission: showing how powerful the sun is and that we can save the earth by building massive solar power plants in the deserts.

People still think that they are doing well with having solar panels on roofs and saving energy, but it distracts attention from what really needs to be done: For a real energy transition, the entire energy that is being used worldwide, must be generated sustainably. To do so, we have to build many solar plants of hundreds-by-hundreds kilometers. It is essential that the sun always shines, without clouds. There is only one way to achieve this and that is to use the deserts worldwide.

In fact, there is no lack of energy as long as we generate solar energy in the deserts, and it can be produced particularly cheaply. You can, without remorse, drive as much in your car as you want, and it doesn't matter if you fly to faraway places several times a year.
You can read all about the mission on the following websites:

German Association for Concentrated Solar Power
Vereniging voor Zonnekrachtcentrales

Deutscher Industrieverband Concentrated Solar Power DCSP

Another promising technique for green energy is geothermal energy.

Solar bike vs velomobile and recumbent bike

You can also cycle with less power with velomobiles and recumbent bicycles. However, these bicycles have disadvantages that the solar bike does not have:

• Difficult to transport due to large size and weight.
• Not suitable for uphill use.
• A low sitting position is less safe and obstructs the view.

With the solar bike, however, I can cycle anywhere. A Velomobile has the advantage that you can cycle comfortably in all weather conditions, while the solar bike only works in sunny weather.

Maxun One cockpit display

The Maxun One solarbike has six meters on the handlebar. I have developed round gauges, which are much more visible than the widely used LCD displays. I will put these meters on the market when the chip shortage is over. The meters only need 5V power supply because they use Bluetooth. The weight is less than 10g each.

Maxun e-bike cockpit display

The following parameters are measured:

Solar bike F.A.Q.

Can any electric bicycle be used?

No, it is necessary for the ebike to be lightweight and drive very energy-efficiently. Normal electric bicycles are much too heavy and cumbersome. See this article.

What does the addition "One" mean?

The addition One is for the solar bike(s) made by myself.

When is the solar bike for sale?

Because I’m not an entrepreneur type, setting up a large production facility is not an option. The bike would anyway be quite expensive, only available to the happy few. I have plans to sell some Maxun One solarbikes in the future. The prototype is handmade, which cannot be produced in larger quantities. There is still much work to be done.

Is the prototype for sale?

No, not even for €30000.

What is the use of the solar panels?

You would think that the use of the PV panels is obvious, but many people wonder what they are for. The solar panels generate the power for the motor.

How many microcontrollers does the solarbike have?

The solar bike contains 12 microcontroller boards of my own design: cable killer, 3x Watt-meter PCB, 6x meter (Psolar, Pmotor, fuel, Volt, speed and rpm), 2 for the LED lights.
Four microcontrollers are used in the BMS, motor controller, and the two MPPT solar charge controllers.

What kind of motor is used?

Temporarily, a Q85 front hub motor is used. Later, I want to use the Xiongda dual-speed hub motor.

Should we additional pedal too?

At sunny summer weather, you don't need to pedal at all. 

What is the speed by solar energy?

On flat roads, a speed of 15mph or 25km/h is easily achieved. Sometimes even 30km/h.

What is the average solar power?

The rated power is 240W. At full sun, the power is usually between 150W and 200W.

What is the maximum solar power?

The PV power can sometimes be higher than the rated power: 300W. This occurs at partly cloudy weather. When the sun shines through the clouds, the PV panels receive the direct sunlight but also sunlight reflected by the clouds.

Maximum battery charging current

The maximum charging current can be very high, namely 10A at 30V and 300W solar power. Caution: most batteries will explode at this current. Only LiFePO4 batteries can handle such high charge currents.

PV power on light cloudy days

Even on semi-cloudy days or at low sun, the solar panels deliver usually more than 100W; this gives enough pedal support.

PV power with partly cloudy weather

Partly cloudy weather
These kind of clouds sometimes completely blocks the sun

Can the PV panels be removed?

The panels can be removed in a few seconds.

Do the solar panels suffer from shadow as do usual PV panels?

Because the bicycle is regularly shaded, the panels and their electronics have a special design which effectively reduces the shadow influence.

Are the solar panels not dangerous while driving?

Some people find the solar bike dangerous. But what about cars and trucks racing along cyclists? That’s seriously dangerous. Compared to that, the solar bike is harmless. The solar panels automatically move away should a collision occur.

Why does it have a battery?

The solar bike needs a small battery because the instantaneous power, for example at acceleration or at uphill, may be larger than the solar panels provide. In addition, the electronics requires a battery. However, if sufficient solar energy is received, the battery doesn't have to deliver any power.

Should the battery be charged?

At accelerating and driving uphill with motor support, the battery is needed, which has to be sufficiently charged by the solar panels on the go. Therefore we need to save energy on flat roads so that solar energy is left over to charge the battery.

Is it stable at parking?

The solar bike has a very stable side stand for parking. But with strong winds, the solar bike must be parked against a pole or tree.

Is absence of sun a problem?

In absence of sun we have to pedal when the battery is empty also. But the Maxun One rides almost as light as a road bike because the panels form no additional wind load.

How big is the motor power?

The motor power is 250W (limited by law in Europe), that does not seem much but it's enough for a speed of 27km/h. Do not compare the light running Maxun One solar bike with a common energy guzzling heavy e-bike. It makes no sense to use a bigger motor, there is not more solar energy available. In the future, a mid drive motor will be used instead of the front motor, which will increase the uphill performance a lot. 

Is the bike sensitive to side winds?

Strong crosswinds are rarely a problem, just don't drive too fast.

What is the speed uphill?

With the temporarily front hub motor, you have to additional pedal a little uphill to supply extra energy, but most energy comes from the motor. 

Was it difficult to make?

Yes, although the solar bike looks uncomplicated. But it is very difficult to come out to a simple looking solution.

What is the advantage over a ebike with just a battery?

The solar panels can provide an energy of 1500Wh per day. A high quality battery of this size has a weight of at least 15kg.

Can the solar panels be made smaller?

There is no trick which makes it possible to use much smaller PV panels. With the use of aerospace solar cells, which have the highest efficiency, the panel size can be reduced with 25%, but these would make the Maxun One $100,000 more expensive. The received solar energy is proportional to the surface area of the PV panels and so a smaller size means less power. Note that vertical panels receive just very little solar energy.

The solar panels may seem large at first glance, but that's because you haven't seen them before. After a while you don't know better and they seem rather small. Furthermore, the solar bike is not larger than a child transport bicycle. So it is not necessary to reduce the solar panels and we don't want to reduce solar power. 

What do you think of an overhead top panel?

This has drawbacks: it is top heavy, catches much more wind and it looks like a Pope mobile.

Can the panels be tilted towards the sun?

Yes, you can tilt the solar panels while driving and parking. Here, the battery is charged on February 2021.

Tilted solar panels on february 2021

How long takes battery charging during parking?

If the battery is completely discharged, recharging by the PV panels takes about one hour.

What is used, a torque sensor pedal assist or cadence sensor pedal assist?

I prefer cadence sensor pedal assist with up/down push buttons for motor power control. Torque sensor paddle assists is pointless with my solarbike because most of the time you don't have to pedal at all. Only rotating the pedal is needed, because that is mandatory.

Are there any drawbacks?

The bike is much faster than a normal bike, but if you take the time into account that you spend with answering questions from interested people, the bike is just as fast.

Solar-bike from Maastricht 2014Solar bike at Liege 2014

Things that still need to be done

Although the solarbike is practically fully developed, there is still a lot of work to be done:

• Making a production description. The collection of electronic designs, mechanical CAD files and other documents contains 24000 files in 4700 folders.
• Various improvements can be made, for example, it has recently become possible to glue the electrical connections of the solar cells.
• An important point of concern is the construction of lightweight sandwich panels, for which there is no solution yet, see: The development of extremely lightweight sandwich panels.
• Because there are no carbon front forks for hub motors on the market, a special front fork is now being developed in China. See this article: First custom carbon fork special made for hub motors.

Building the Maxun solarbike may be an interesting project for a technical university too.
I have found out that the Xiongda dual-speed hub motor is the best option for building a lightweight ebike, see: Review Xiongda dual-speed hub motor.

The history of the solar bike

In April 2010, I started with the Maxun solar bike. The first project was the research of a lightweight PV encapsulation, which took 1 year. Here is a photo from an article in the newspaper about this:

Albert van Dalen with the PV cell curvetracer from 2010

How to plan the best route for the most sun

Solarbike shadow on frontpanelShadow on solar panelSunCalc shows the movement of the sun and sunlight-phase for a certain day at a certain placeSuncalc path of the sun

To know the sun orientation over time, we can use the website SunCalc.

Solar cycling for dummies

• Departure with a charged battery
• Keep the motor power and solar power in balance
• Prior to a pause you may use extra energy
• Take sunny roads rather than shady roads if possible
• A lower speed requires less power, even uphill
• A little extra pedalling saves a lot of energy

The Sun Trip

There are now many people who have built a solar bike. See here the participants of The Sun Trip contest:

Participating cyclists in The Sun Trip challenge

Contact me

Feel free to contact me if you want to know anything about the solarbike, I will be happy to help you.

Media

Zonnig bergopwaarts Limburger 14-12-2010

Telegraaf 18-12-2014

L1 Maastricht 10-1-2015