Solar Cooker Coffee:
Brought To You By The
Power Of The Sun

I’m starting to wonder if there’s anything a solar cooker can’t do.

It can cook meals, pasteurize water, reduce dependence on firewood, cut down on pollution, and… roast your coffee beans?

Yes indeed, brothers Mike and David Hartkop of Solar Roast Coffee have put a new spin on the solar cooker by inventing a solar powered coffee roaster.

SolarPowerBeginner recently had the chance to ask David Hartkop some questions about Solar Roast
 and how it harnesses the power of the sun. Here’s what he had to say:

SolarPowerBeginner: How did you first get interested in solar power?

David Hartkop: I had a fascination with burning things under a magnifying glass starting from the time I was 5 or 6. Some part of this is an outgrowth of that!

On the other hand, I really have been interested in all sorts of renewable energy. I was fascinated with ocean wave power in college and geothermal energy, but I always seem to come back to Solar because it is readily available where I live. It is not too difficult to directly experiment with it, and it actually is a wonderful energy source.

SolarPowerBeginner: Your first solar coffee roaster was what some people may know as a parabolic solar cooker. Tell us about the design process and any adjustments that had to be made for coffee roasting.

David Hartkop: It really was a parabolic cooker that we made out of the frame of a satellite dish. All of the changes we made to what would have been a straightforward design had to do with the size requirements.

Some initial experiments showed that we would need to have a dish at least 10 feet in diameter to roast 3-4 pounds of coffee at the 500˚F we wanted to achieve.

We also wanted the roaster to be as low to the ground as possible so that we could safely access it. This resulted in using a 10 foot diameter satellite dish frame, but covering it with individually aligned mirrors rather than coating the surface with something reflective.

solar cooker 4

The individual mirrors let me set the focal point lower and off-center so that the roaster would be below the dish, rather than projecting out from the exact center.

SolarPowerBeginner: How does the taste of coffee roasted in a solar cooker and the time required to roast the beans differ from conventional coffee roasting?

David Hartkop: The time is the same: 18 to 21 minutes per batch. Our biggest roaster roasts in the same time as the smaller versions.

We think the coffee tastes better because our roasters are designed to hold in the steam, smoke, and hot gasses to a larger degree than a conventional gas-fired coffee roaster. This gives it a richer more aromatic taste.

SolarPowerBeginner: How does your current solar coffee roaster differ from the original solar cooker you designed?

David Hartkop: Our current roaster has a solar concentrator that is almost ten-times the area of our first roaster.

The current roaster is located in a small building near the concentrator, and receives hot air ducted down from the concentrator’s receiver. It is a less-direct system, but an important design compromise, because both the roaster and the concentrator are so large. It is able to roast a max. of 30 lb of coffee per batch.

It is also equipped with a propane burner that we use to pre-heat when it is cold, or to supply extra heat as needed through the rosting day.

We purchase energy credits from solar providers through the Bonneville Environmental foundation to ‘offset’ the carbon released through this process.

It should be noted that 100% of the electrical (non-heat) energy used for coffee roasting comes from our bank of solar panels. We are not yet 100% solar powered, but we are carbon neutral!

SolarPowerBeginner: You are currently located in Colorado. Is there enough sun all year to roast coffee using solar power?

David Hartkop: Yes, there is! It is an excellent place to be in terms of solar exposure and clear days throughout the year.

SolarPowerBeginner: Has the increased acceptance of solar power as a viable power source caused more people to also “go solar” with their coffee?

David Hartkop: Well, that remains to be seen; it is certainly our hope!

SolarPowerBeginner: People use solar cookers to cook just about anything. Have you experimented with cooking any food with the sun or does the solar coffee roasting take up enough of your time?

David Hartkop: Right now we are just roasting coffee. We’ve talked about nuts or drying different things, etc etc. Coffee is a specialty and a world of its own; there really is enough to maintain and improve upon in that field to keep us quite busy!

For more on the Hartkop Brothers and their company check out the Solar Roast Website.