Solar Vehicle Project Turns up the Heat


University of Alberta
Student Contributor


The sun is shining, classes are out and except for the occasional May flurry, summer seems to be well on its way. For student project leader Glen Rees and his team of engineering students, there is no better time to turn up the heat in their current design of the University of Alberta Solar Vehicle Project. Since last September, the team has completely overhauled its previous solar car design, the Inukshuk, and plans to have the new model ready for competition in the summer of 2005.

Solar Trails
Inukshuk and the team during the summer of 2003, when they went from Edmonton to Nisku and back. This exposed newer members to how the car handled and helped direct design efforts.

How it Works
How does it work? Glen explains it this way.
First, you need sunlight. The sunlight’s photons hit the solar cells on the car. Many solar cells are connected together on the top of the vehicle body, forming modules. There are five of these modules on the car and they are connected in parallel to form the array.

Once the photons hit, electrons are released within the solar cells and this produces a current. The solar cells are designed to produce a certain voltage at all times. Based on this voltage held in the solar cells and the current produced from the released electrons, a certain amount of power is produced.

The solar cells are connected to a battery via a power point tracker to ensure maximum charging.

The batteries power two sections. The low voltage section steps down the voltage of the battery to a usable amount for the monitoring and safety electronics of the car. The high voltage section runs 96 volts into the motor via a motor controller which converts the DC voltage to usable AC.
From there, the car works much like a normal vehicle.

Big Design Changes
This new design promises to be the most ambitious the team has taken on. Glen says that among the results will be increased speed and efficiency.

The team wants to rectify is weight. The Inukshuk was over designed because the first car, the Nanook, did not even qualify. The Inukshuk was built to work, which overshadowed other issues.

The team is changing from the original lead-acid batteries, weighing 350 lb., to a lithium ion battery weighing 65 lb. Extra monitoring will be necessary to keep the more finicky battery stable, but the batteries are otherwise comparable in performance. It’s a small price to pay for the weight reduction.

A bigger, more efficient array of solar cells will deliver more power to the battery. The Inukshuk array covered about eight square metres of the car’s top, the new array will cover about 10 square metres.

Each array is made up of solar cells 10 cm by 10 cm in size. Efficiency increases to 20 per cent from 14 per cent. Currently the greatest amount of efficiency that can be gained from the best solar cells is about 32 per cent.

The motor will be the same as that of previous models: a 96-volt, DC brushless, 5 kW power engine operating at 95 per cent efficiency when running at 1,100 r.p.m. This motor will propel the car, the team hopes, to speeds greater than 70 km/h and a top speed of 110km/h.

Cruising speed will use only power provided by the sun through the solar cells, while top speed will require power to be drawn from the battery.

Casing and Chassis
One section of car will be casing, covering the under parts as well as providing an enclosed windshield. The array sits atop the casing.

Then there’s the chassis. The Inukshuk had a “space frame,” with the upper and lower components of the car made separately and then put together at the end. The new model will have a “semi-monocoque chassis,” including the roll cage and exterior frame. This new chassis will be made of composite materials to decrease weight.

An idea is in the works that would have the casing move up from the chassis with the use of small hydraulics, like the mouth of an animal opening.

The team is also looking at new features. A cruise control option will be added to save on power – constant acceleration and deceleration puts a lot of strain on the batteries. Further, the team will be making the new car a two-seater, allowing a passenger to ride along.

Plans for the Summer
The new car is being designed for the upcoming North American Solar Challenge, which will start in Houston, Tex., run north to Winnipeg, and finally carry on across the Prairies to Calgary. The start is in mid-July 2005, and the race is expected to take 10 days.

The solar team is currently in the design stage and hopes to be building as of September 2004. This summer the team hopes to gain partners in order to set up funds for the project.

The team will also be upgrading education presentations for next year. Team members visit with students in Grades 4-12 to discuss alternative energy and the solar car.

Upcoming Events for the Team
You can see the team this summer at a few events in Edmonton.
On July 1, the team participates in Strathcona County’s Canada Day celebration in Sherwood Park. The Inukshuk will be there and the team will meet the public.
The team will be in the Klondike Days Parade, July 22 in Edmonton.

Adopt-a-Cell Program
If you’d like to help sponsor the project in an affordable way, the adopt-a-cell program may be for you. Adopt a solar cell for $20 each or $50 for three. In return, your name will be displayed on the vehicle website and sponsorship banners.

You will also be invited to the official unveiling of the new vehicle, and will receive a certificate acknowledging your sponsorship and a photo of the team and the car.


On Adopt-A-Cell
And the
Solar Vehicle Project
E-mail Glen Rees at
grees@ualberta.ca or solarcar@ualberta.ca.


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