How It Works
The mechanics of the Solar Bike are pretty simple.

1. Solar panels, which are mounted on a small trailer pulled behind the bicycle collect free energy from the sun.

2. This energy is used to charge two batteries located in the middle of the frame between the riders legs. Energy is being taken from the batteries and going to the motor at the same time that energy is going from the solar panels and charging the batteries. This is what gives the solar bike its extended range.

3. Energy is taken from the batteries and used to power the motor which is mounted above the rear wheel. The motor turns a belt which in turn turns the wheel.

4. A charge controller is used to make sure the batteries never become too drained or over filled by the solar panels, ensuring the longevity of the batteries.

5. A throttle is located on the handle bars allowing the rider to control the speed of the bike.

6. Pedals still work if the rider would like to use them for fun or to extend the range of the bike.

Solar Bike and Solar Ride

Introduction

The Solar Bike was originally conceived to help demonstrate simply and effectively the practical applications of renewable energy, to be used as part of the ECO Centre’s ongoing education programme, including the schools programme. It was seen as a novel way of capturing the attention of the largely school age audience, normally in attendance at ECO Centre presentations.

It was felt that much more could be gained by using the bike and bike ride to promote a wealth of issues.

These issues included: the consequences of our extravagant use of the world's dwindling energy resources; practical ways we can all conserve energy; green transport and what is being done to encourage people out of cars and onto bicycles; the non-polluting renewable energy technologies.

In preparation, staff pre-arranged visits to school on the route. The aim was to give presentations on the issues outlined and to engage the pupils in the Home Energy Trail project. As the climax to the visit the two cyclists would arrive with the Solar Bike and the control bike, and pupils could ask questions of the riders about the bikes and the ride itself.

Each stop lasted about an hour, twenty minutes for the presentation and the remainder of the time given over to the exciting question and answer sessions, and the obligatory photographs.

The Solar Bike, having been designed once and improved upon, need a thorough road testing. This was to see that, even its current form, the solar add-on and motor stood up to the rigours of a 500 mile trip up hill and down dale around Wales.

The other main objective was to see if the motorised bike actually provided any net benefit to its rider.

We capitalised on the current interest in all things to do with the Internet, and mounted a page on the web which followed the tour. This can now be found at:-

With the aims and objectives of the project in place, it was time to go.

The School Visits

There was a very warm reception in every school. Each school was evidently very pleased at having been ‘chosen’ to be a point of call for the Solar Bike as it went around Wales.

The presentations went down well, the audiences were very responsive and, indeed, very knowledgeable on some of the points raised. Teachers seemed happy, especially those who were using the Internet site as a point of reference for the pupils to follow the progress of the ride. To actually have everyone arrive at their school as predicted was obviously fulfilling.

The Home Energy Trails were distributed to willing recipients with the promise that the school that returned the highest proportion would be in receipt of up to ?000 worth of energy efficiency measures from the local Electricity Board.

The schools part of the project exceeded the expectations of the organisers. It would appear that, on the basis of the success with arranging visits for the Solar Ride, every school in Wales would be happy to have a visit.

The total number reached was 21, which accounted for about 2700 pupils. A ludable achievement.

The Solar Bike

The Ride afforded the ECO Centre the chance to test the bike to the limit.

In its second stage of development the bike was equipped with a rear wheel mounted motor, geared so that it was only effective on fairly steep hills (and steeper).

It was important to know if the battery would be adequately charged by the solar panels under the variable conditions on offer from the Welsh climate. And similarly whether the battery would withstand the sort of use it would get from being used to drive the motor on some of the steepest hills in Wales.

For monitoring this, regular measurements of the voltage of the battery were taken at the beginning and end of every cycling day.

The main question that need to be addressed was that of the benefit to the rider using the bike notwithstanding the additional weight of the battery, motor and solar panels. Or put more simply. Is it any good?

The ride was set up so that there were two cyclists on two identical bicycles. One was equipped with the solar add-on kit, and the other wasn’t. But the second did have to carry the panniers for the two riders. In terms of weight the bicycles were almost identical.

Heart rates were used as the measure of the efficiency of the riders in each case. A heart rate monitor was strapped to each at the start of the ride. The riders had the responsibility of taken their heart rates in the morning, at the top of a steep hill and at the end of the day. Thus providing comparable data on peak and average heart rates.

Results

The bikes and the riders completed the ride intact.

The bike performed well within the expectations of the team responsible for its development. The battery did not go flat, and it remained adequately charged at all stages.

The total potential charging power available from the photovoltaic panels is 30W. Refer to the following table.

Important Information

Therefore:

Charge time will increase dramatically under cloudy of diffuse conditions (~ 10-20% of full charge). The charge will also be dependant on the angle of the sun upon the panels.

Average heart rate:

Unfortunately this is not an accurate figure at all. Whenever one of the riders walked away from their bike the heart rate figure would immediately drop to zero. Therefore there would be a figure that says more about how long the riders have spent out of range of the monitor than how hard we have been working.

Maximum heart rate:

The maximum heart rate figure was measured on the steepest hill in each section of the ride and it was discovered that without motor assistance the riders heart rates were very similar. Therefore, on a section where the heart rates were similar it shows that there were no hills steep enough to warrant the use of the motor and where there is a big difference between the figures it shows the difference in effort between motor assistance and leg power. These figures seem to suggest that the motor is worth between 30 and 40 beats a minute, which is the difference between a comfortable work load such as walking up a couple of flights of stairs and being on the limit of what one can sustain.

Technical Specifications

The Bicycles:- 2 x Barrier Reef Barracuda supplied by Moore Large Co Ltd, Derby. 1 bike will be equipped with the solar assisted electric motor.

Specs:- Aluminium frame 7000 series; rear and front mech, Shimano Acera X; chain ring, Shimano STX; wheels, alloy Alessi Challenger; hubs, Shimano Parallax; V brakes, Lizaro; gear changers, Grip Shift; handlebars, 6061 T6 aluminium with Club Roost bar ends; alloy seat post; saddle, Stella Royale Eclipse; headset YST Corp CS 558; tyres, Nokia Slick City Runners; rack, Acor seat post.

Power and motor:- EMD Motor 5/447, 200W, 12V, gearbox GB4; Battery, Hawker Energy Genesis 25Ah; Solar Panels, 2 x 5 watt Solarex panels.