For over a decade, the U.S. Department of Energy’s Solar Decathlon competition has challenged college students around the world to build the most energy-efficient solar-powered house. The biennial event is impressive for sure (just look at last year’s winning design), but it’s also pretty darn expensive, with schools commonly spending upwards of $250,000 for each project and sometimes exceeding the million-dollar mark.

After attending the two most recent Solar Decathlons, Suzette Bienvenue, an energy education specialist at the Sacramento Municipal Utility District (SMUD), was inspired to create a similar event that would be accessible to all kinds of schools, including local community colleges with more limited budgets. The solution? Tiny houses.

Typically measuring between 100 and 400 square feet (as opposed to the thousand-square-footers commonly seen at the Solar Decathlon), tiny houses can easily be built for under $50,000. Add in the general popularity of these micro dwellings right now, and Bienvenue has a workable idea: a collegiate competition loosely modeled after the Solar Decathlon, but using tiny houses as the vehicle to explore sustainable building techniques and energy-saving strategies.

SMUD’s Tiny House Competition, open to any university or college in California, first put out a call for participants in 2014. Two years later, the first-of-its-kind event culminated in a showcase at Sacramento’s Consumnes River College last weekend, where ten schools showed up to demo their solar-powered, zero net energy houses on wheels.

While Bienvenue expected the public event to draw a variety of niche groups (“hippie types, survivalists, retirees”), the audience was more like a “slice of America” and “much more mainstream,” she says in a phone interview. In the end, some 20,000 people had come by to tour the houses, well over the anticipated figure of 3,000.

Here’s a closer look at the the two tiny houses that won big at the competition, chosen by expert judges hailing from fields like architecture, energy, and communications.

The top honor for the best tiny house overall (monetary prizes were provided by partners and sponsors) went to the rEvolve House from Santa Clara University. The off-grid home clocks in at 238 square feet and was conceived as a short-term, low-cost housing solution for local non-profit Operation Freedom Paws, which matches veterans with potential service dogs. Interior highlights include: a kitchen with a seating bench and fold-down table, 35-square-foot wet room with a dry-flush toilet, built-in shelving, and an elevated living/sleeping area with a Murphy bed. There’s also a roof deck accessible via a spiral staircase.

Built of energy-efficient Structural Insulated Panels, the house runs on eight 330w Sunmodule solar panels, stores energy in Cradle-to-Cradle-certified saltwater batteries, and can rotate on a Colossun solar tracking ring to follow the sun and maximize solar efficiency. The rEvolve House also won awards in eight other categories, including “Best Integrated Lighting” and “Best Kitchen Design.”

University of California, Berkeley’s THIMBY (that is, Tiny House in My Backyard) took home four awards, including those for “Best Craftsmanship” and “Water Conservation.” Designed as the pilot unit in a community of zero net energy tiny houses in Richmond, California, the 170-square-foot home will eventually go to a newlywed, eco-conscious couple in the area.

Running on a 2.2 kW PV array, the house stores energy in a 6.4 kWh Tesla Powerwall lithium ion battery, which Elon Musk unveiled to much fanfare last spring. There’s also a vertical “living wall” with an activated carbon filter combo that can recycle greywater for non-potable use. Still in development is a smart home monitoring system that can consult weather forecasts for optimal heating loads.

For more information on the competition and a peek into other tiny house entries, head over to the official competition website.