Adopting Solar Bicycles to Reduce GHG Emissions

A solar bicycle is also an Electric Vehicle (EV) - it uses electric motors for propulsion. But this is where the similarity ends. A solar bicycle has its own renewable generator and hence it is a true net-zero vehicle. Using a solar bicycle, you can help ease the global warming, pollution.., congestion crisis

Global warming alarms are sounding loud and clear. Meanwhile, worldwide, a disruptive change is taking place – the obsolete US (private cars) model is making way for the Netherlands’ (bicycle) model that encourages use of bicycles and public transport systems. However, the majority of Indians are addicted to the use of self-owned (private) two or four wheelers, and to a sedentary lifestyle with little health consciousness. In such a scenario, solar bicycles can work as an effective enabler to wake up the Indian masses and shift them from the US model to the Netherlands’ model speedily.

Our attempt, here, is to bootstrap ‘solar’ over the Netherlands’ (bicycle) model. It has been observed that 80% of the road trips in India have trip lengths less than 8 kms. These are ideal for solar bicycles.

What is a solar vehicle?

A solar vehicle is a motorised ultra-light vehicle that is powered by solar energy. Since a Photo-Voltaic (PV) solar panel is an integral part of a solar vehicle, it is capable of harnessing solar energy even when the bicycle is in motion.

Solar vehicles are the only ‘complete’ vehicles in the mobility sector from ‘source’ (solar panel) to ‘sink’ (motor). Due to the size and weight of the solar panel, earlier, it was only possible to design solar tricycles and solar quadricycles. But lately, with better technologies having higher efficiencies it has become possible to design a well-engineered solar bicycle that is capable of harnessing adequate solar energy to meet its own consumption needs for travel up to 25 kms per day.

Solar bicycles present a clean (does not pollute), green (source from nature) and renewable (source is naturally renewable) mobility solution. They are the most efficient machines built for personal commute and personal cargo mobility. A solar cycle can travel a distance of 150 metres with 1 Wh  (= 0.86 cal) of solar energy. For the same distance to be covered by pedalling, 3.6 cal of (human) energy would be expended. Humans are about four times less efficient when pedalling, and ten times less efficient when jogging or running. No other electric vehicle or ICE vehicle comes close to solar bicycles when it comes to efficiency and GHG reduction.

How is a solar bicycle different from E-bicycles or other E vehicles?

A solar bicycle is also an Electric Vehicle (EV) – it uses electric motors for propulsion. But this is where the similarity ends. A solar bicycle has its own renewable generator – and hence is a true net-zero vehicle. Solar energy is the most abundant of all energy resources and can be harnessed even in cloudy weather. Due to the ubiquitous nature of solar radiation outdoors, the demand on the storage element (Li-ion battery) of a solar bicycle is less stringent. Hence, a small Li-ion battery of capacity less than 300Wh suffices.

Other EVs are powered autonomously by a large battery or a fuel cell or by a collector system with electricity from extravehicular sources. The energy to the battery or fuel cell or collector system needs to be replenished from an external source – which is majorly fossil fuel based. Hence, an EV does not help in curbing global warming unless assisted by a renewable source.

Figure 1. A solar bicycle has its own renewable generator…

The Net Metering Tariffs offered by the Electric Utilities in India under the direction of the Electricity Regulatory Commissions do not encourage consumers to charge their EVs from their own solar rooftops; on the contrary they promote offset of their solar generation against consumption of fossil fuel based generation to charge their EVs in the evening or night. Coupled with EV subsidies, they not only fail to curb global warming, but also result in fossil fuel based generation demand peaking in the evening. This could result in load shedding (forced shutdown of electric supply by the utilities during peak hours) in the forthcoming years.

Understanding Greenhouse Gas (GHG) emissions

Definition: Scope 1 and Scope 2 emissions are those that are owned or controlled by an organisation.

  • Scope 1 covers emissions from sources that an organisation owns or controls directly – for example from burning fuel in its fleet of ICE vehicles.
  • Scope 2 are emissions that an organisation produces indirectly from the energy it purchases and uses. For example, the emissions from the generation of electricity, used to power up EVs, fall into this category.

Definition: Scope 3 emissions are a consequence of the activities of the organisation but occur from sources not owned or controlled by it.

  • Scope 3 encompasses emissions that are not produced by the organisation itself, nor from the result of activities from assets owned or controlled by them, but by those that it’s indirectly responsible for, up and down its value chain. An example of this is when it buys, uses and disposes off products from suppliers. Scope 3 emissions include all sources not within the scope 1 and 2 boundaries.

For many businesses, Scope 3 emissions account for more than 70% of their carbon footprints. Scope 3 emissions are under the control of suppliers or customers, so they are affected by decisions made outside the company.

Figure 2. Different types (Scope) of Greenhouse Gas Emissions…

How to reduce your greenhouse gas emissions?

  • Develop a full greenhouse gas emissions inventory
  • Incorporate Scope 1, Scope 2 and Scope 3 emissions
  • Understand your full value chain emissions
  • Focus your efforts on the greatest reduction opportunities

Treat Climate Change as a business problem rather than solely as a Corporate Social Responsibility. Committing to reach net zero will involve tackling your Scope 3 emissions.

How can solar bicycles make a significant ghg impact in the mobility sector?

A solar bicycle represents the first R in Reduce-Reuse-Recycle, the three Rs of waste management. Reduce means to cut back on the amount of trash we generate.

The bigger the vehicle – say a car weighing 2000 kgs, the more the trash; it also means more energy required to manufacture it and to run it. This means that even the Scope 3 emissions are very high.

In contrast, a solar bicycle weighing less than 30 kgs, needs less energy to manufacture. It also runs on a renewable energy source – solar and consumes less than 6.6 Wh/km (5.7 cal/km or 23.7 kJ/km). A ride to a destination 8 kms away and back would consume less than 120 Watts with zero GHG emission.

However, it is not the low consumption of the solar bicycle that needs focus. Instead, it is a very high amount of CO2 ranging from 170 to 200 gms per km that a car emits that needs to be eliminated. Travelling sixteen kms using a solar bicycle instead of a car would result in savings of 3 kgs of CO2 or GHG emission.

Characteristic features of a solar bicycle 

  • Zero running cost (no petrol/gas/electricity consumed)
  • Net zero travel: You can help ease the global warming, pollution, congestion crisis
  • Supports a mix of powered and manual riding modes
  • Throttle Mode: Battery Powered (max. 15 kms/day)

  • Manual Pedal Mode: Pedal mode (no battery consumed)

  • Pedal Assist Mode: 1 or 3 levels (LCD version) of pedal assist,  less power consumed from battery compared to throttle. (increases travel distance to 30 kms/day)

  • Good for your Heart: Lead a healthy lifestyle by riding the solar bicycle to work or to school. The Pedal assist levels can be adjusted to suit your workout and make your ride enjoyable and stress free.
  • Equipped with a solar charge controller having ability to charge the battery from the attached solar panel.
  • Solar Panel mounted on a suspension that absorbs shocks. Panel tilt adjustable so that the panel can face the sun.
  • Powerful headlight, loud horn, rear view mirror, led tail light and a powerful brake light, for safety.

Specifications of the solar bicycle BEM  Savitré

  • Retrofit on a 26” bicycle – Hero MISS INDIA  or Tata  Stryder. Total weight less than 27 kgs.
  • Powerful BLDC Hub Motor: 36V – 250 Watt with Motor Controller
  • Solar Panel 40W, 12V, with a spring loaded suspension. The rear carrier mounted panel is detachable and tilt adjustable so as to face the sun to harvest maximum solar energy from the panel. The patented suspension absorbs shocks while riding and prevents solar panel breakage if the bicycle falls.
  • BEM  Savitré Solar MPPT Battery Charge Controller with OLED Display. The patented hybrid controller has ability to extract maximum power from the attached 40W solar panel to charge the battery in the shortest possible time
  • Maximum Speed: 30 kms/hour on full throttle.
  • Be totally off fossil fuels and the electric grid for travel up to 20 kms/day on solar energy.
  • On a normal sunny day, it offers a solar powered throttle ride to a destination within 8 km radius and back. Ideal for daily commute to work/ school.
  • Lithium Ion Battery 200Wh, 36V, 5.2 Ah
  • Typical Charge Time: 4 to 5 hours, Discharge time: 1 to 2 hours.
  • Pedal Assist Sensor (PAS) with 1 or 3 (LCD) assist levels
  • LED Display shows Battery Charge Level, Optional: LCD displays battery voltage, speed, odometer, trip km, cruise control, etc.
  • Head Light, Strip LED Tail Light, Brake Light, Horn, Bell, Rear View Mirror, Al. alloy centre stand, Tool set, air pump, cable lock

EVs don’t help the environment, yet are preferred by customers. Why?

The government has distorted the market by offering subsidies to EVs and to solar rooftop installations. The solar rooftop scheme was originally introduced to promote self-consumption of solar generation. Instead the consumers are observed to bank their solar generation with the utilities during the day, only to withdraw them later at night, to charge their EVs. The flawed net-metering tariff is misused by consumer to draw (import) expensive fossil fuel based energy at night free of cost against the previously exported solar generated units banked with the utility.

This results in a dual problem for the electric utility that (a) needs to search for a buyer for the solar energy exported while (b) compensating the solar rooftop customer by offering expensive carbon based or fossil fuel based energy at night at a discounted price that matches the lower cost of solar energy.

What are the advantages of solar bicycles?

A solar bicycle truly represents all the four ‘R’s (RENEW, REDUCE, REUSE, RECYCLE), especially ‘renew’ and ‘reduce’. It is truly green with zero emissions. Pedalling a solar bicycle is better than jogging or running or walking as it places less strain on your knees by your body weight. Riding a solar bicycle to work in a pedal assist mode is a surer bet to losing calories rather than enrollment into weight loss programs offered by gymnasiums.

Solar bicycles have pedals unlike scooters, motor-cycles, cars or buses (regardless of whether they are ICE or EVs). Enables the commuter to reach home safely by pedalling the solar bicycle in an event its battery drains off. This offers safety and confidence particularly to young girls.

Frequent charging from the abundant solar source puts less demand on the Li-ion battery capacity. A small 5 Ah or 180 Wh battery suffices the need of a solar bicycle unlike other EVs including electric bicycles that need a more powerful battery with a much higher capacity. Frequent charging also means smaller discharges – that in turn means longer battery life.

Unlike other simple or electric bicycles, the solar bicycle can be used as a commuter cum cargo bicycle. Lexan resin based side plates along with ‘S’ hooks on the carrier allow 40 kgs of cargo weight to be carried in bags (20 kgs on either side).

What are ‘carbon offsets’ and how can it help lower the cost of solar bicycles?

A carbon credit represents 1 tonne of CO2e that an organisation is permitted to emit. The number of credits issued to the organisation by a regulatory body represents its emissions limit or cap. Over-emitters turn to the carbon market to purchase carbon credits from an under-emitting organisation.

A carbon offset is also measured in tonnes of CO2e. However, unlike carbon credits that are created or distributed by a regulatory body and limited to regulatory jurisdictions, carbon offsets can be traded freely on voluntary markets around the world.

A solar bicycle with nil emissions can be viewed as a renewable energy project towards a carbon reduction project. Carbon offsets can be thought of as a measurement unit to compensate an organisation investing in green project initiatives such as solar bicycles, which remove emissions. The organisation can in turn use these carbon offsets to lower down the cost of the solar bicycle so as to make it more attractive and affordable to the bicycle purchaser.


A typical passenger vehicle that drives around 18,500 kms/year emits about 4.6 metric tons of CO2 per
year (@ 250 gms/km). One ton of CO2 is emitted every 4,000 kms.

A solar bicycle that runs approx. 16 kms per day would run about 4,000 kms in a year. It can thus compensate for one ton of CO2 every year.  Over a period of 3 years, it can compensate for 3 ton of CO2.

Carbon Offsets can be sold at USD 40/ ton. Hence a total carbon offset of USD 120 can be claimed against 3 ton of CO2. The cost of the solar bicycle can thus be lowered down by 9,000, from25,000 to `16,000, making it more affordable to the buyer.

How can the local bodies help in promoting bicycles?

Separate ‘green’ lanes can be demarcated on the roads for bicycles like it was done in Ahmedabad along with the Bus Rapid Transit System (BRTS) that is popular by the name ‘Janmarg’.

One of the design features of the BRTS system that won several prestigious awards was a dedicated bicycle track that could offer the last mile connectivity – a vital component to popularise public transportation. A smart city project to ease last mile connectivity through dockless bikes was also planned a few years back.

Figure 3. Dedicated bicycle track as part of BRTS Ahmedabad…

What were the engineering challenges faced while developing a solar bicycle?

A PV solar panel has a tempered glass sheet as a top layer and, therefore, is considered to be delicate or fragile. One of the challenges was to design a suspension system that will prevent the panel from getting damaged when the bicycle topples over when it is in a stationary condition or when it is in motion. A patented loosely mounted solar panel suspension system was indigenously developed particularly for the solar bicycle.

Figure 3. The Characteristics of MPPT Charge Controller (Boost)

Another challenge was to design a battery charging system that can charge the battery in the shortest possible time from a size and weight constrained solar panel. The solar bicycle is fitted with a microcontroller based battery charge controller that is driven by a sophisticated MPPT (Maximum Power Point Tracking) software algorithm giving it an ability to extract maximum power from the attached 40W solar panel (dimensions 638 x 355 x 25 mm) for delivery to the battery. Due to this, on a normal sunny day, it takes less time (only approx. 4 to 5 hours) to fully charge the 36V, 5Ah (180Wh) battery.

Vithal Kamat has a Doctorate in Artificial Intelligence from the University of New Brunswick, Canada as a Commonwealth Scholar in 1996. He completed Masters in Control and Instrumentation from IIT Bombay. He is associated with the Centre for Apparent Energy Research, Anand, Gujarat.

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