The EVs of the 2015 Solar Decathlon

The biennual Solar Decathlon returned to Southern California last week, with a twist.

There is a significant difference in the rules this year; a first in the contest s 13-year history. Teams and their houses can now compete in an electric commuting category by making enough electricity to operate a battery-electric vehicle.

The new contest category is called Commuting , and it joins existing categories such as Market Appeal and Affordability . It is a measured category (rather than juried). Full points (100) are awarded for driving 25 miles or more in two hours or less eight times during the contest week. Reduced points are earned for driving less than the required number of miles. Commuting points are awarded throughout the competition.

The car commuting energy is part of the overall house electrical consumption. The house and car together must not exceed 175 kWh of usage throughout the entire competition. Even though the cars could be charged at local public charge stations, for this competition the teams must forego that option, only charging from the house.

A student from the Stevens Institute of Technology SU+RE HOUSE explained that this commuting electricity can represent one-third of the electricity used during the contest. So this has resulted in larger solar arrays this year to make up the difference.

But this extra electricity can have a positive impact on the environment. Richard King, founder and director of the Solar Decathlon, says that two fossil-fuel cars produce as much carbon as an entire house on a yearly basis. So replacing them with something that can drive on solar energy is a no-brainer.

With the addition of electric commuting this year, the Solar Decathlon houses accomplish more than ever before. The Solar Decathlon has long been about net-zero homes. This year it moves beyond to simulate a complete net-zero lifestyle.

The Solar Decathlon is a multi-discipline event. Amid the excitement of building these houses, and the innovative design and ideas contained within them, the car parked next to the house may not get that much attention. But it’s clear that the car makes as much of an impact on the environment as the house itself. So it’s worth shining a spotlight on these vehicles.

Great Participation

12 of the 14 homes have opted to include an electric vehicle and compete in the Commuting category. The BMW i3 and Nissan LEAF are by far the top vehicle choices.

California Polytechnic State University, San Luis Obispo

Clemson University

  • House: Indigo Pine
  • Vehicle: BMW i3
  • Charge Station: Bosch Power Max

Crowder College and Drury University

Missouri University of Science and Technology

  • House: Nest Home
  • Vehicle: Nissan LEAF
  • Charge Station: Schneider EVlink

California State University, Sacramento

Stevens Institute of Technology

State University of New York at Alfred College of Technology and Alfred University

  • House: ALF
  • Vehicle: BMW i3
  • Charge Station: GE Wattstation

University of California, Irvine; Chapman University; Irvine Valley College; and Saddleback College

The University of Texas at Austin and Technische Universitaet Muenchen

University at Buffalo, The State University of New York

  • House: GRoW
  • Vehicle: Nissan LEAF
  • Charge Station: Schneider EVlink

University of California, Davis

West Virginia University and University of Roma Tor Vergata

  • House: stile
  • Vehicle: VW e-Golf

Efficiency is Key

Since the Solar Decathlon is primarily centered around house design and operation, and the electric car is using electricity that could otherwise be used by the house, vehicle efficiency is a key consideration.

The CSU Sacramento Reflect team are enjoying driving a 2015 smart ED, on loan from Jim Fairchild. According to Sacramento State Professor Mikael Anderson, the team chose this model because they figured the smallest EV would be the most efficient.

The Texas/Germany NexusHaus team students consider their BMW i3, on loan from BMW California, to be expensive relative to a student budget. But they love the fit and finish, and really appreciate the efficiency. According to University of Texas at Austin Assistant Professor Petra Liedl, the students are eager to figure out the most efficient way to drive the car day by day. Petra s husband was on the engineering team that developed the i3 at BMW Munich, so it’s safe to say that she feels doubly proud having the BMW grace their house. The Texas/Germany team expects to get all 100 Commuting points by the end of the Decathlon.

Drury/Crowder students researched electric car efficiency and chose a Chevy Electric Spark mainly because of its low energy usage per mile (an EPA-rated 28 kWh/100 mi) The team published a video of their mentor describing the rationale behind the Chevy Spark choice.

Squeezing Out Even More Efficiency

One team has gone even further in pursuit of efficiency. Casa del Sol, by Team Orange County is the only house to feature a new Princeton Power Systems CA-10 power converter.

The converter allows an electric vehicle to charge at a rate of 10kW directly from the home solar array.” The direct DC-DC conversion reduces losses by over 50%. This increased efficiency means less impact on the solar array or the grid, and reduced charging time.

Even better, the station can output power to the grid (V2G) or the home (V2H).

The station is currently compatible with vehicles that support the CHAdeMO charging standard. Some of the vehicles that can charge using this standard are:

  • Kia Soul EV
  • Nissan LEAF
  • Tesla Model S (via optional external adapter)
  • Zero Motorcycles (via optional inlet)

If you want to geek out on more details and data sheets, check out the page for the Princeton Power Systems “DRI-10” inverter, upon which the “CA-10” is based.

Project Managers Alex McDonald and Moritz Limpinsel dealt with some challenges with the power converter, including shipping damage, and firmware issues. But during testing, they measured 96% efficiency charging directly from DC power. The team thinks the power converter may be an attractive option for solar home owners with electric cars in the near future. Team OC is very confident that they’ll win their 100 Commuting points.

NRG eVgo donated the converter, and Princeton Power is providing design consulting and on-site support.

Better Driving Experience

The Drury/Crowder ShelteR3 team has been pleasantly surprised by the EV driving experience. Drury student Vicas Jagwani had never driven an electric car before. It was an interesting feeling to not listen to the noise of a running engine, reports Vicas. The Nissan LEAF is one of the smoothest vehicles I have driven. He sees the strong merits of not having to fill a tank with gas, or even do oil changes.

The Drury/Crowder team expects to win all available 100 Commuting points. They credit the way [their] house has been designed and structured in order to generate a good amount of power.

Persistence Pays Off

We can all learn something from the persistence shown by the Alfred College team. They were not able to find a sponsor to donate an EV for the event. They also were not able to find a car rental service anywhere near the Decathlon that had EVs available. But they didn’t give up.

Alfred Student Avery Sandler says that the team finally found a car rental place in Los Angeles that had the BMW i3, so they rented it from there. They looked all over for the GE Wattstation they wanted, and tracked down a Lowe’s store that had the last unit in stock in the area and snapped it up.

Avery says that the students enjoyed driving the EV so much that they’ve already driven it the required number of miles for the competition. They found the BMW i3 to be a well built car that is fast and efficient.

Alfred College has gotten all the commuting points for every event, and, according to Avery, will get the 100 points at the end.

We expect the students will get one last bit of fun as they drive the BMW i3 back to the rental place in L.A.

An Inspirational Virtuous Cycle

The greatest potential of the Solar Decathlon may lie in its ability to inspire students and visitors to strive for an electric car lifestyle of their own.

Normally, mentors inspire their students, but sometimes the inspiration can flow in the other direction. Economics Professor Steve Mullins is a mentor to the Crowder/Drury ShelteR3 team. Since joining the team, student discussions and research on the competition requirements have inspired Dr. Mullins to make two significant investments in clean, renewable, and affordable energy. Eight 435 watt photovoltaic solar panels have been installed on the roof of his garage and a Chevy Spark elective vehicle (EV) sits inside charging. Dr. Mullins, who appears in the above video, now happily commutes daily in his own EV.

A Worthwhile Event

The 2015 Solar Decathlon opens to the public again today after a brief midweek hiatus. The second (and last) weekend will run from Thursday the 15th through Sunday, October 18. It takes place at the Orange County Great Park in Irvine, California. Please consider attending or rooting these students on in any way you can.

The Decathlon program is run by the U.S. Department of Energy. Major sponsors include Edison International, Schneider Electric, and Wells Fargo. Visit solardecathlon.gov for more details, such as the latest standings for all teams, or just the commuting points.


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