Solar E-Bike Generates Power Through Its Wheels

Electric bicycle manufacturer PHOSGO is taking an unconventional approach to range anxiety by placing solar panels directly inside the wheels of its latest e-bike.

The PHOSGO Go5 Series uses four wheel-integrated photovoltaic panels with a combined peak capacity of 200 watts. The system can produce electricity while the bicycle is moving and continue charging its battery when parked in sunlight.

PHOSGO claims that its internal testing generated approximately 138 Wh of energy during four effective hours of sunlight. Based on the company’s estimated consumption rate, that could recover up to 17 miles, or approximately 27 kilometres, of range in one sunny day.

Those figures, however, should not be interpreted as guaranteed real-world performance. The energy production and range estimates are based primarily on tests and calculations provided by PHOSGO. An independent prototype review confirmed that the solar system works, but also found that charging performance can be substantially lower under variable weather conditions.

How Does the PHOSGO Go5 Solar E-Bike Work?

Most solar electric bicycle concepts place photovoltaic panels on a rear cargo rack, canopy or separate trailer. PHOSGO instead uses the otherwise open surface inside the front and rear wheels.

The Go5 has two photovoltaic panels on each wheel. Each panel is rated at up to 50 W, giving the complete system a theoretical peak output of 200 W.

The panels use back-contact solar cells that PHOSGO says offer conversion efficiency of more than 26 percent. Positioning the electrical contacts behind the cells reduces obstruction on the light-facing surface.

Generating electricity inside rotating wheels also creates an engineering challenge: the power must be transferred from a moving component to the stationary bicycle frame.

PHOSGO says it solves this problem with a proprietary conductive hub. Electricity generated in the wheels passes through the hub to an MPPT solar controller integrated into the bike.

The system then operates in two modes:

• While riding, solar energy supplements the motor and reduces the rate at which the battery is depleted.
• While parked in sunlight, the system directs the available solar power into the battery.

This means the Go5 is more accurately described as a solar-assisted electric bike than a bicycle capable of relying entirely on solar energy.

Can the Solar Wheels Add 27 Kilometres of Range Per Day?

PHOSGO reports that the system produced approximately 138 Wh during an internal test involving four effective hours of sunlight.

The company calculates average consumption at around 8 Wh per mile. Using that figure, 138 Wh would provide approximately 17 miles, or 27 kilometres, of recovered range.

This is a best-case estimate rather than a fixed daily result. Actual solar recovery will depend on several variables, including:

• Intensity and duration of sunlight
• Cloud cover and shade
• Season and geographical location
• Orientation of the bicycle
• Angle of the panels relative to the sun
• Terrain and elevation
• Rider and cargo weight
• Motor assistance level
• Riding speed and style
• Tyre pressure
• Electrical conversion losses

The vertical position of the panels creates an additional limitation. Unlike a conventional solar panel that can be angled directly towards the sun, only part of the wheel-mounted system may receive strong sunlight at any given moment.

Although the complete installation is rated at 200 W peak, both sides of both wheels are unlikely to achieve maximum output simultaneously during normal use.

What Did Independent Testing Find?

Notebookcheck tested a pre-production prototype of the PHOSGO Go5 Ultra and confirmed that the wheel-mounted panels generated electricity.

The test bicycle arrived with an empty battery and was placed on an open lawn in direct sunlight. After approximately five minutes, the solar controller collected enough energy to activate the display. A direct measurement from the front panel showed an output of 22 volts, which was consistent with the manufacturer’s specifications.

However, the battery gained only around one percent during a three-hour period with changing cloud and sunlight conditions.

The publication concluded that the solar panels functioned as a supplementary trickle charger rather than a replacement for conventional charging. In favourable conditions, the system could help maintain the battery or extend the time between visits to a power outlet. It should not be expected to recharge a large e-bike battery rapidly.

Because the tested bicycle was a pre-production prototype, its hardware and power management system may differ from the final version delivered to customers.

PHOSGO Go5 Ultra Specifications

The Go5 Ultra is the more powerful model in the new range. It is designed for longer journeys, camping and routes where access to conventional charging may be limited.

The United States version is listed with the following specifications:

• Bafang M430 mid-drive motor
• 750 W nominal motor output
• Up to 910 W peak output
• Up to 150 Nm of torque
• 720 Wh battery using LG cells
• Motor assistance up to 28 mph, or 45 km/h
• Shimano eight-speed drivetrain
• Electronic gear shifting
• 200 W peak solar capacity
• GPS, 4G and Bluetooth connectivity
• Electronic motor lock
• Anti-theft alerts
• Mobile application support

These motor and speed figures apply to the US configuration.

PHOSGO says European versions will comply with local pedelec regulations. They are expected to use a 250 W motor with assistance limited to 25 km/h. Consequently, European customers should not expect the same power and assisted top speed advertised for the American version.

Can the PHOSGO Go5 Ultra Really Travel 225 Kilometres?

PHOSGO estimates that the Go5 Ultra’s 720 Wh battery can provide a base range of up to 90 miles, or approximately 145 kilometres, without including solar recovery.

Under the company’s defined multi-day conditions, the combined distance before the next plug-in charge could reportedly reach 140 miles, or around 225 kilometres.

The 225-kilometre figure does not represent a single continuous ride powered by one battery charge.

It assumes that:

• The journey takes place over several days
• The bike receives favourable sunlight during riding and stops
• The solar panels recover energy each day
• An efficient motor assistance level is selected
• Terrain, weather and rider weight remain favourable

The claimed total is therefore a cumulative multi-day estimate that includes repeated solar energy recovery. It should not be presented as the bicycle’s standard battery-only range.

Independent testing of the production version will be necessary to determine how closely typical users can approach these figures.

PHOSGO Go5 Pro Offers a Smaller Battery

The Go5 Pro is the second model in the series. It uses the same 200 W solar wheel system but combines it with a smaller battery and a lower-powered motor.

PHOSGO lists the US version with:

• 500 W Bafang M430 mid-drive motor
• Up to 140 Nm of torque
• 480 Wh battery
• Motor assistance up to 20 mph, or 32 km/h
• Battery range of up to 60 miles, or 97 kilometres
• Multi-day combined range of up to 110 miles, or 177 kilometres, including solar recovery

As with the Ultra, the European version is expected to use a 250 W pedal-assist system limited to 25 km/h.

Could Solar Wheel Panels Affect Handling?

Integrating large solid surfaces into bicycle wheels raises questions about crosswind stability and steering behaviour.

During Notebookcheck’s prototype test, the wheel covers created noticeable pressure in moderate side winds. The reviewer reported that the front wheel required active steering input to maintain a straight line. A slight increase in steering resistance was also observed during low-speed turns.

PHOSGO argues that placing the panels inside the wheels is less disruptive than mounting a large external solar array above or behind the bicycle. The low position may help preserve the centre of gravity and reduce exposure compared with elevated solar structures.

The company says its own testing found stable handling in normal conditions, including moderate wind. It has also acknowledged that dedicated crosswind testing is continuing.

Other issues identified during the independent prototype test included:

• Increased sensitivity to side winds
• Water being directed upwards from the covered wheels in wet conditions
• The absence of full mudguards
• A nearly five percent overnight battery loss while the bicycle was switched off
• Early production quality concerns involving the valve extension and pedal threads

These findings relate to a pre-production unit. Whether they have been addressed in the final model will become clearer when customer-ready bicycles undergo further independent testing.

Is It Really the World’s First Solar E-Bike?

PHOSGO promotes the Go5 as the world’s first mass-produced solar electric bicycle series for global consumers.

The broader claim of being the world’s first solar e-bike is difficult to support. Solar-assisted electric bicycles and cargo bikes existed before the Go5, including designs that carry panels on rear boxes, canopies or trailers.

The Go5’s more defensible point of difference is its integration method. PHOSGO has placed the photovoltaic cells directly within both bicycle wheels while retaining the general form of a conventional e-bike.

It may therefore be more accurate to describe the Go5 as one of the first consumer-focused electric bicycle ranges to integrate solar panels structurally into both wheels.

Is the PHOSGO Go5 Available to Buy?

The PHOSGO Go5 Series is currently being offered through an Indiegogo crowdfunding campaign rather than established retail channels.

At launch, early supporter packages started at approximately:

• $1,899 for the Go5 Pro
• $2,499 for the Go5 Ultra

Campaign prices, delivery estimates, specifications and eligible shipping regions may change.

Backing a crowdfunding campaign is also different from purchasing a finished product from a conventional retailer. Potential risks include manufacturing delays, changes to specifications, limited servicing options and the possibility that delivery may not occur as originally planned.

Prospective buyers should examine:

• Current campaign terms
• Estimated delivery dates
• Shipping availability
• Import duties and taxes
• Lithium battery transport restrictions
• Warranty coverage
• Replacement part availability
• Local service options
• Refund conditions
• Final production specifications

Waiting for independent reviews of a production-ready model may be the safer option for customers who are not comfortable with crowdfunding risk.

A Clever Concept That Still Needs Real-World Validation

The PHOSGO Go5 challenges the usual approach to electric vehicle range.

Instead of asking only where a larger battery can be installed, the designers have explored how an existing surface can generate energy. That principle could influence future mobility products ranging from bicycles and trailers to recreational and agricultural vehicles.

Wheel-integrated solar panels may be especially useful during camping trips, long outdoor stops and multi-day journeys away from the electricity grid. Even modest charging could reduce battery consumption and extend the time between conventional charges.

Current evidence nevertheless suggests that the solar installation should be viewed as a supplementary energy source.

The 200 W peak capacity, 27 kilometres of potential daily recovery and 225-kilometre combined range are notable claims, but they depend heavily on favourable conditions and manufacturer-defined calculations.

Independent testing has established that the solar wheels can generate electricity. It has not yet confirmed that ordinary users will consistently achieve PHOSGO’s maximum range figures.

The final production model will need further testing in different climates, terrain and wind conditions before the practical value of wheel-integrated solar charging can be fully assessed.