Thank you Starlink!

Starlink Co. has yet again provided us with stickers and decals for Zephyr, free of charge. Starlink is a leader in digital printing, and the kind folks at Starlink even expedited our decals order so we can have them on the car before FSGP/ASC! Thank you very much for your support!


The beautiful decals adorning Zephyr’s top shell
The CalSol & Cal decals also made it on Polytechnique Montreal’s Esteban!

FSGP/ASC2014: We Have Withdrawn

Saturday July 19th was CalSol’s first and last day participating in the Formula Sun Grand Prix 2014 at the Circuit of the Americas. CalSol successfully got Zephyr on the track on Saturday morning. We were able to get a few laps around the track but soon discovered an electrical problem that caused the car to turn itself off after exceeding speeds around 30mph. To provide some context, it was necessary for Zephyr to reliably drive with a speed upwards of 60mph in order for us to take Zephyr on public roads. On the Circuit of the Americas track, one of the very first hurdles was getting past a steep hill before going around the first corner. After a few laps around the track, Zephyr started to cut off its power while climbing the hill.

Zephyr at the starting line of FSGP
Zephyr at the starting line of FSGP

We discovered that the electrical current limit of one of our systems was set too low, thus triggering a safety feature to shut down the car.  This is an anomaly, as we have been able to take the car to speeds upwards of 50mph. We examined every connector, board, wire, and piece of software that we could get our hands on. We were at a constant hustle to get the car running on the track again—but each time it would stall after ten seconds of acceleration. Members frantically ran to and fro along the track with tools, computers, and debuggers.

This went on for six hours. Unfortunately, by the end of the day we had only completed five laps out of the required forty-eight. Though ASC can grant provisional qualification to teams that have a high potential, CalSol decided to withdraw from the race simply because racing a car with an unreliable electrical system on public highways posed a safety risk for the team.

We are very disappointed. We had come out to Texas to race to Minnesota and our FSGP/ASC2014 experience was cut short.

Without a doubt, forfeiting ASC2014 was one of the team’s lowest and the most humbling moments. We learned that the importance of extensive testing wasn’t just some rookie comment, but rather it was an absolute necessity for any team who wants to ensure a reliable vehicle. We experienced first-hand what it meant to push ourselves even when we thought we could not be pushed any further. And the most encouraging part is, we got to interact with the kind and intelligent solar car community who worked across team affiliations to get every car up and running.

In ASC 2012, CalSol reached a respectable 4th place finish on a simple but well-tested vehicle. After ASC 2012, CalSol went great lengths to build a solar vehicle with the most efficient aerodynamics and solar cells, lightest body and chassis, and the most advanced manufacturing techniques that the team had ever undertaken. Despite the measures taken to create the most advanced solar car, we fell short in producing a reliable vehicle.

Like every car, Zephyr succeeded in some aspects and failed in others.

Before packing up, there was one more thing we were able to do in order to help the solar car community. Polytechnique Montréal turned sharply on a tight corner on the track and snapped one of their car’s two Mitsuba motors. The team ingeniously found a way to power the car with a single motor in mere hours, and conditionally qualified for ASC2014. However, being short one motor without a spare was not a comfortable situation for the Montréal team. Since CalSol’s Zephyr uses the same equipment, we let Montréal borrow two Mitsuba motors for the race.

In 2003, CalSol had motor issues and ended up racing with University of Kentucky’s motor. This week we were able to pay that kindness forward. I like to call it solar car karma. Even though we will not be able to race, we are still honored to participate in such an amazing community. We hope that our competitors are able to reach their fullest potential.

CalSol and Montreal collaborating to provide Montreal functional motors for ASC2014
CalSol and Montreal collaborating to provide Montreal functional motors for ASC2014
Montreal's damaged motor
Montreal’s damaged motor

With a great deal of dedication, perseverance, and solar car karma, we are making great progress in solar car innovation. We are using this experience as a stepping-stone for accelerated progress with Zephyr. We’ve identified key issues with over-eager safety systems and are developing a better testing strategy. The best days of this car have yet to be seen, and we are excited to see where we go next.

Min Ju Lee

CalSol team lead

CalSol 2014 team photo
CalSol 2014 team photo


Thank you GM for providing us with two Yukons for the race! While Zephyr will not make the trip up to Minnesota, several team members will travel with other teams up north to get the ASC 2014 experience
Thank you GM for providing us with two Yukons for the race! While Zephyr will not make the trip up to Minnesota, several team members will travel with other teams up north to partake in the ASC 2014 racing experience.

FSGP/ASC2014 Update: Scrutineering

Hello everyone! Sorry to keep you in the dark during this past week… if you kept up with our facebook posts, you’d know that this past week was filled with a whole lotta fixing for our team.

The team arrived in Austin, TX with Zephyr that needed a lot of fixing. First of all, Scrutineering was set to start on Monday. Due to our need to fix our defective braking system as described in our previous blog post in addition to an exploded trailer tire, we arrived in Austin on late Monday afternoon to start scrutineering on Tuesday. We added new lights, replaced enclosures, designed temperature sensing system, made new boards, soldered a whole lotta everything, cut here and taped there. We re-did them twice, thrice, four times, as many times until we were ensured that faulty systems were fixed and that we can ensure the driver’s safety.

List of to-do on Wednesday afternoon
List of to-do on Wednesday afternoon

FSGP (Formula Sun Grand Prix) was set to start on Thursday, but we could not get on the track on Thursday because we still had consequential problems that needed to be debugged. In order to qualify for ASC, we must complete 60 laps in 1 day or 90 in two consecutive days. We decided to take our time to ensure that the problems were fixed for good before putting the car and the driver on a track race, to ensure the safety and performance of Zephyr and its driver.

CalSol members busily fixing up Zephyr's mechanical issues
CalSol members busily fixing up Zephyr’s electrical / mechanical issues

Finally on Friday, we were able to get a good to go “green” sticker on all scrutineering stations– solar (modified our array size), body & sizing (installed new lights, modified enclosures, added rear view camera, added paddings), BPS (redesigned and implemented a new temperature sensing system), mechanical (added crumple zones), electrical (added electrical hazard labels), drivers (qualified Ellande, Nick, Aditya, and Aly to be our drivers), and dynamic testing.

Despite the troubles we went through fixing up Zephyr, it performed exquisitely well in dynamic testing. Aditya shocked the team when he zipped through slalom and figure 8 test in record time.

Figure 8 test during Dynamic Scrutineering
Figure 8 test during Dynamic Scrutineering

The team is so excited to get some time on the track race tomorrow. CalSol is team #6– wish us luck & abundant sunshines!

Crazy thunderstorm on Thursday evening + unforeseen fire alarm == rain dance from the teams
Crazy thunderstorm on Thursday evening + unforeseen fire alarm == rain dance from the teams

Thank you, Kreysler & Associates!

Going with the trend of honoring our top three sponsors for Zephyr / ASC 2014, this shout out is for Kreysler & Associates.

Kresyler donated time on their 3 and 5-axis CNCs to machine our molds at free of charge.

FSGP/ASC2014: Pre-Departure, Day 0

What a rough week it’s been. The team had planned on departing to Austin, TX on Thursday morning. But as luck would have it, we blew out our braking system on Zephyr while testing on Wednesday evening.

There were several fatal faults in both the design and implementation of the original brakes. ASC regulation states so that we must have a balanced, co-reactive, dual-braking system, in addition to a parking brake. The braking failure was simple– none of the brakes supplied enough braking power, and eventually blew out our master cylinders. However, the problems were complex– not only did we have to find a way to increase the braking power, we had to redesign and manufacture a system that fit in our incredibly cramped space at the foot of the driver. We faced severe time and design limitations. Since a faulty braking system was capable of causing serious damage to the car and the driver, our only option was to postpone our departure and fix the brakes if we wanted a shot at safely racing Zephyr.

Our members Jake, Sam, Tristan, Chris, and Kyle worked day and night, to design and implement a working braking system by Friday afternoon. It was incredibly stressful and tiring for everyone, especially the aforementioned designer / manufacturers of the new braking system. We bought out relevant components off of every nearby auto parts store we could find; worked in two machine shops for 48 consecutive hours; flew out a member to LA on a very short notice to optimize our modified journey from Berkeley to Texas; cancelled all reservations and made new ones; and many of us even left our full-time industry jobs early and commuted to Berkeley to help.

But as teamwork and resilience would have it, we successfully tested a braking test, stopping 65kmph-Zephyr with 5.1 m/s^2 deceleration. With the new brakes, Zephyr is projected to pass scrutineering, but members will continue to make adjustments to improve the braking performance for safety reasons.

Sam literally lived in the Richmond Field Station from Wednesday to Friday, to help design and manufacture the new brakes.
Sam literally lived in the Richmond Field Station from Wednesday to Friday, to help design and manufacture the new brakes.
Jake and his blackened hands!
Jake and his blackened hands!

As stressful as this week was, in retrospect it was good that we identified the problem prior to the race. This is why there is so much emphasis on testing— often times, it is the well-traveled solar car that will win the SunRayce instead of the flashiest solar car loaded with features. Had we encountered this problem during the race, we would have lost a lot of time to troubleshoot this on the road.

The crew is now on the road to Texas. Wish them safe travels!

Pre-departure photo!
Pre-departure photo!

Thank You SunPower!

With the Formula Sun Grand Prix / American Solar Challenge 2014 approaching in just a month, CalSol is in the process of organizing a list of generous friends and company sponsors who made it possible for us to engineer Zephyr and to enter in the SunRayce. In particular, the team decided to give a shout-out to our top three sponsors for this race. This shout-out to SunPower is dear to me because it’s what got me so hooked onto the team and also what led me to become the engineer that I am today.

Team members preparing for solar cell caulking.
Team members preparing for solar cell caulking.


SunPower Corporation is based in San Jose, Calif, and is America’s premier high-efficiency silicon solar cell designer & manufacturer. Almost all competitive teams participating in the American Solar Challenge use SunPower cells because not only are they efficient, they are also incredibly reliable. CalSol has been using SunPower cells dating as early as the late 90s, but we had never established a connection with the company until 2013.

With CalSol encapsulating our own solar cells for the first time this build season, we needed a lot of help. We talked to awesome local and corporate companies such as D2 Solar and Dunmore— the kind engineers from D2 solar and Dunmore gave us many samples to test and generously donated their time to troubleshoot our problems. We learned a lot, but we were far from being able to produce perfectly encapsulated panels.

By half-luck and half-coincidence, I got in contact with SunPower’s senior manager in business development. She is also a Cal grad and was intrigued by our project– and from there, the solar team’s progress took off quickly. We received bare SunPower solar cells, as well as invaluable engineering support from SunPower engineers. It’s been more than a year since SunPower and CalSol has been working closely together– and for over a year, the CalSol members have had the privilege of learning about the solar industry first-hand with the leading solar company in the world. And more importantly, we’ve had so much fun doing engineering.


Chatting up with SunPower's CEO Tom Werner at 2013 All-Hands meeting
Chatting up with SunPower’s CEO Tom Werner at 2013 All-Hands meeting
Impulse, the team, and SunPower's executive officers at the Richmond, Calif. facility.
Impulse, the team, and SunPower’s executive officers at the Richmond, Calif. facility.


Solar cell encapsulation @ the San Jose HQ
Solar cell encapsulation @ the San Jose HQ

The team is recognizing SunPower as one of our top three sponsors for Zephyr / ASC 2014. SunPower has not only provided CalSol with generous in-kind donation, but perhaps more importantly, invaluable engineering and moral support to the team. We know that the people at SunPower are busy individuals, and we cannot thank you enough for taking your time to help us with everything solar-related for Zephyr!


We’re Famous… on our School’s Newspaper, the Daily Cal!

The Daily Cal's Article about our work!

A couple weeks ago, a few CalSol members met up with a staff from the Daily Californian, which is UC Berkeley’s largest student-run news organization. And on Wednesday, Nov 2oth, the article about our work went online as well as on the front page of the Thursday’s paper!

DailyCal Article

Check out what the Daily Cal had to say about our work in CalSol! It is titled: UC Berkeley solar-powered-car team works into night months before the race!

UC Berkeley solar powered car team works into the night months before next race   The Daily Californian

New Year, New Team: Gearing up for ASC 2014!

Greetings! We took a hiatus from blogging over the summer, but CalSol has been working hard over the last year to prepare for the American Solar Challenge 2014. As you will find out from our every-two-week posts, the team has acquired multitude of projects and talented members over the last few months who continue to turn Zephyr from a concept to reality.

CalSol @ RFS Tour
Composites Training @ RFS

In particular, the team was excited to find new details of the ASC 2014: it will start in Austin, Texas and end in St. Paul, Minnesota!

Exact locations of stage/checkpoints are still being finalized, but what we know for now:

  • Mon, July 21 (2014): Start in Austin, TX with a checkpoint in (TBD), TX
  • Tue, July 22: Arrive at stage stop in Norman, OK
  • Wed, July 23: Depart Norman, OK with a checkpoint in Wichita, KS
  • Thu, July 24: Arrive at stage stop in Overland Park, KS
  • Fri, July 25: Depart Overland Park, KS and arrive at stage stop in Omaha, NE
  • Sat, July 26: Depart Omaha, NE with a checkpoint in Ames, IA
  • Sun, July 27: Arrive at stage stop in La Crosse, WI
  • Mon, July 28: Finish in St. Paul/Minneapolis, MN

What we think the route might be:

View Larger Map

We are pretty stoked about this northbound driving across the central U.S! More updates to come from our other leads later.

Min Ju

Team Lead, CalSol

Putting the SOLAR in CalSol, the Solar Vehicle Team

Greetings! My name is Min Ju, and I’m the lead for the newly-created Solar subteam. Here is a sneak peak of what the Solar subteam and I have been up to.