PUEBLO, CO—Even if you park a few blocks away from the Solar Roast Coffee building, you can smell the acidic odor of roasting coffee beans wafting down Pueblo’s Main Street.

I was out in the area for an unrelated story and had heard that Solar Roast was a cool place to sit and work. But when I found out that the coffee shop was also the retail face of the only major commercial solar-powered coffee roasting company in the US, I e-mailed owner Mike Harktop to see if I could get a tour. He congenially agreed.

Move over Elon Musk, this business is OG.

The company was started by Mike and his brother David in 2004, with the two fashioning a makeshift solar-powered coffee roaster out of 100 mirrors, a broccoli strainer, and a satellite dish. That’s right—instead of relying on traditional photovoltaic cell panels converting photons into electricity and running a coffee roasting machine that way, the brothers started out building a solar thermal system, directing light and heat directly onto one pound of raw coffee at a time.

The brothers, who are from Oregon originally, moved the operation out to Pueblo, Colorado as they worked on their solar roasting design. Pueblo is southeast of the Rocky Mountains and situated in a “banana belt”—a region that’s warmer and sunnier than the area surrounding it. The city of 200,000 gets 3,470 hours of sunshine a year, or 78 percent of the sunshine available to it. Plus, it’s just two hours south of Denver and it's home to a Colorado State University campus.

The brothers eventually built a rig they called Helios III, a bigger solar thermal roaster rooted to a trailer that could cook up to five pounds of coffee at a time. They set the machine up outside of Pueblo and built a plastic geodesic dome around it to protect the coffee from birds and the weather.

Megan Geuss

Megan Geuss

Megan Geuss

Megan Geuss

Megan Geuss

Megan Geuss



Solar Roast

Solar Roast

Megan Geuss

The most ambitious solar thermal setup was the Helios IV, which was built in Oregon and later reconstructed in Colorado—this version was 35 feet in diameter, moved automatically to follow the sun’s path in the sky, and roasted 30 pounds of coffee at a time. “Pueblo shut us down at one point because they thought we were building a death ray,” Mike told me. All the while, the company was racking up customers from small coffee houses to specialty groceries.

But that iteration never quite worked the way the brothers wanted it to, and when they received a business development grant from the city of Pueblo in 2012, they decided to go a slightly more conventional route—setting up photovoltaic solar panels on the roof of an old multi-use building in downtown Pueblo and using the resulting electricity to power a more traditional coffee roaster that the brothers cobbled together.

The decision to move to electricity over solar thermal roasting was an economical one. The Helios IV cost $250,000 to build in total and conditions were less than ideal for employees who had to work inside the geodesic dome, with temperatures rising to 130° Fahrenheit in the summer (although Mike noted that the dome would get up to a pleasant 50° in the winter when the surrounding plains were a bitter 10°). By contrast, the company’s current roaster cost $100,000 to build and can be operated onsite next to the cafe.

The new solar roaster is grid tied, and in addition to running the company's roasting operations, Mike says the solar panels on the buildings’ roof also cover about 30 percent of the cafe’s electricity needs as well.

The roaster itself is heavily insulated to keep the roasting chamber hot. Mike said their beans are roasted at temperatures over 300° and it can take more than two hours for the internal temperature of the roaster to drop even 100° because of the insulation. By the same token, getting the temperature up in the roaster is a challenge. Using just electricity, it takes two to three hours to heat the inside of the roaster to the desired temperatures, so the company added a natural gas generator to the roasting apparatus. With the generator, it only takes 30 minutes to get the roaster up to the ideal temperature in the morning, and then Solar Roast switches to electricity to maintain that temperature and power the roaster throughout the rest of the day.

During the roasting process, the chaff from the beans will pop off and go through the base of the machine, while a cyclone filter removes smaller particulates. The roaster doesn’t need to protect against carbon monoxide or exhaust contamination because, of course, the majority of the process it completely electric. Mike says that also prevents the contents of the roaster (and the roaster itself) from lighting on fire, which is an occasional problem with more traditional roasters.

While Mike was giving me a tour of the facility, he walked over to an unassuming hulk of metal tucked away to the left of the doorway to the packing room. It looked like a DIY spaceship, with exposed areas covered in Reynolds Wrap. This, he told me, was the body of the massive Helios IV. The founder said he plans to cannibalize it this year to build a second electric roaster for his facility. The work should take a couple of months and will require a bit of patchwork. “For solar thermal, air flow’s completely different,” Mike said, pointing out a hole in the roaster’s body where a hole should not, traditionally be.

But Mike didn’t seem too sentimental about cutting up the massive handmade roaster. “It needs to be repurposed for its new life,” he told me.