We have received a lot of questions about the right cookware to use with SolSource, and the quick answer is: you can use almost anything! (See our FAQs for what won’t work.) But just like on a traditional stove, there is lots of room for nuance depending on what you want to cook and how you want to do it. I hope this quick guide can help you choose the right tool for your next solar cooked meal.
1. Use cookware with a matte- or dark-colored bottom.
This one is really important. SolSource aims plenty of power at your pot, but if that pot has a nice polished stainless steel base, it will reflect much of the sunlight right back towards the Sun, just like a mirror. In fact, using cookware with a “matte” surface on the bottom is far more important than the particular color. Take a look at how much light from my laser pen is absorbed or reflected by these three items that I grabbed off my desk:
Black-bottomed pans are of course the best choice. But as you can see from the demo, the difference between the light reflection on black and white business cards is much smaller than the difference between the white card and the shiny stainless steel.
2. Use aluminum for frying, grilling, and solid foods
Surprisingly enough, aluminum is by far the best common material for distributing heat evenly across the surface of your cookware. More so than a traditional stove, SolSource focuses a lot of heat in the center of your cookware, so the good heat distribution of aluminum makes it the best choice for solid foods that are grilled, or cooked with a little bit of oil. In these situations you may often be cooking in large batches, and you don’t want a piece to burn or undercook at any one spot on the pan.
The reason aluminum creates an even heat is because of a material property called thermal conductivity. This property indicates how easily heat can move through a material. Materials like copper have very high thermal conductivity, so they’re used in things like heat-sinks and radiators. Materials like silicone rubber have very low thermal conductivity, so they’re used for things like oven mitts or pan handles.
|Material||Thermal Conductivity (W/m•K)|
|Aluminum (3003 Alloy)||163|
|Cast Iron (ASTM A48)||53.3|
|Stainless Steel (302 Alloy)||16.2|
Source: MatWeb, LLC.
In fact, I experimentally verified the heat distribution of aluminum and cast iron in our workshop, using a copper heat pipe to pump 500 watts of heat into each pan, and measuring the temperature at the center and at the edge.
Here is the result
For each pan, the top line represents the temperature at the center, and the lower line represents the temperature at the edge. At 30 minutes, I turned off the heat source and let the pans cool down. The plot shows that while the aluminum pan doesn’t get quite as hot as cast iron right in its center, the temperature difference between the center and the edge is small. You’ll also note that the cast iron pan takes longer to cool down than the aluminum one, which brings me to my next point…
3. Use cast iron or steel for liquid-based foods or very high temperatures.
Iron and steel are less thermally conductive than Aluminum. They hold their heat better, because the rate of heat transfer to the colder air surrounding the pan is slower. This is a great attribute, and the natural movement of the liquid will distribute heat for you with liquid based techniques and foods such as stews, sauces, braising, steaming, and boiling. If you’re really looking for something that stays hot, get a nice thick cast iron pan. This is definitely the way to go if, for example, you’re planning on stewing or baking something for an hour and a half at 350 ºF. The thicker the pan, the more energy it can store.
My experiment also shows that on SolSource, cast iron can achieve very high temperatures right in its center, precisely because it has low thermal conductivity, so the heat builds up in the center instead of spreading to the edges. If you are looking to sear something quickly (heating up the cast iron to its smoke point) cast iron is a good choice.
4. The SolSource Grill Pan
The SolSource Grill Pan is made from thick cast aluminum, anodized with a matte finish on the bottom for solar absorbance, and coated with a ceramic non-stick layer on top. If you flip the SolSource pot stand over, it fits snugly in the ring. When I use the SolSource Grill Plate to grill, I like to add just a little bit of vegetable oil… not so much as to fry, but a little bit on the very edges of the grill ridges helps the heat transfer from the ridges to the food.
5. Safety and Non-Stick Coatings
Now that aluminum cookware is made with a whole rainbow of non-stick coatings, it can be annoying to cut through all the marketing to figure out the implications for your food and your health. Here’s the simplified version:
The first non-stick coating was the now infamous Teflon™ (PTFE), which encountered a lot of controversy when people began to discover that at high temperatures it released a number of toxic gasses and chemicals, chief among them one called PFOA (although as of 2012, PFOA is no longer used in Teflon™ production). Now honestly, there’s no one definitive answer on what temperature is safe for Teflon™ pans with or without PFOA. Some sources say that hazardous quantities of PFOA can be released at as low as 230ºC (446ºF), although DuPont claims that it may be used up to temperatures as high as 260ºC (500ºF). I can’t definitively give an answer here, except to say that for low-temperature techniques, like caramelizing onions or boiling water, there are no substantiated claims of Teflon™ being harmful. However, the possibility of health risks is another reason why with very high temperature techniques, you should consider cast iron over aluminum.
All that said, these days often only the cheaper non-stick pans use Teflon™ coatings, because a new technology has taken hold: ceramic coatings. These claim better scratch-resistance, and they can come in a variety of colors. They’re non-toxic, but they also have a maximum temperature to watch out for, which can vary between different brands. Make sure to check! Our grill plate uses a ceramic coating that can withstand up to 350ºC (662ºF) continuously, which should be well beyond almost any cooking temperature or the smoke point of any cooking oils.
It’s also possible to find uncoated aluminum cookware. It is difficult to find, and I wouldn’t recommend using uncoated aluminum, because it can combine with acidic foods to add unusually large amounts of aluminum to your dish.
6. Your thoughts?
Now that we’ve got hundreds of SolSources out in the wild, I want to hear about your experiences with cookware! Aluminum, Cast Iron, and Stainless Steel are the basics, but there are all kinds of other materials out there in myriad shapes, and I haven’t been able to try them all. Any discoveries to report? I want to know!
Also, just between you and me, I’m working on a super-secret project right now called “Superpan”. If One Earth Designs made another piece of SolSource cookware, what would you want it to be? What would you want it to do? What special super powers should it have?
Write me here, or catch me in the SolSource Facebook Community.
ABOUT ME: I’m Daniel, Electrical Engineer and all-around technical guy here at One Earth Designs. I designed computers at Sun Microsystems and researched power systems at M.I.T. before I joined One Earth Designs looking for an opportunity to make something new and genuinely useful for people.