Making good food with limited resources has always been appealing to me, and camping presents a perfect challenge. I still enjoy cooking over an open campfire, but solar power presents a new opportunity to make great food with simple tools.
Solar-powered system in the galley
With the addition of a slow-cooker to our galley and the upgrade of the teardrop’s solar power system, I began thinking about combining the two. Marilyn’s recipe for “Teardrop Pork Chops” proved we could have dinner ready when we got back to camp in the evening. I wondered if the solar system could effectively power the slow-cooker. Some quick measurements with the “Kill-a-watt” meter showed power usage for the 1 1/2 quart cooker to be well under 100 watts — even on the “high” setting. The “low” setting only consumed about 65 watts. With our 200-watts of solar panels and adequate sun, it should work fine. What to cook for an experiment?
Slow-cookers have always worked well with bean dishes, in fact, they were invented for cooking beans. The combination of low temperatures and long cooking times guarantee tender beans that retain their shape and texture. Chili is an iconic bean dish, and what could be better after a day of camping fun?
Solar Chili
Cooker: 1 1/2 quart oval, powered by a 300-watt Bestek Inverter plugged into a 12-volt, 200-watt solar system
Settings and Cook times: HIGH for 2 to 2 1/2 hours, then LOW for 8 to 9 hours
1/2 pound dried pinto beans, cleaned and soaked overnight and drained
2 cloves of garlic, peeled
1/2 pound of course-ground lean meat, beef, pork or turkey
1 medium onion, chopped
3 ounces of tomato paste or puree
1 1/2 tablespoons of Dixon medium hot (or other high quality) chili powder
1 tablespoon ground cumin
1 teaspoon salt (or to taste)
For serving:
Shredded sharp cheddar cheese
Chopped fresh tomatoes
Chopped green onions
Warm cornbread or saltine crackers
Starting the beans and garlic
Put the soaked and drained beans and whole garlic cloves in the slow cooker, adding enough water to cover. Cover and cook on HIGH until tender but not mushy, 2 to 2 1/2 hours. Drain and discard the garlic.
All ingredients cooking
Meanwhile, brown the ground meat and onions in a large skillet and drain off the fat. Mix the meat, onions, partially-cooked beans, tomato paste, chili powder and cumin in the slow-cooker. Add enough water to cover and stir. Cover and cook on LOW for 8 to 9 hours, stirring occasionally. During the last hour, season with salt. Serve with toppings and warm cornbread.
A solar dining experience
How did we do? Using the measured slow-cooker wattage on high and low settings, a little quick math showed a total power consumption of about 750 watt-hours — within the production capacity of our 200-watt solar system on a sunny day. With the skillet-baked cornbread, all the fixins’ and a glass or two of wine — delicious.
Tasty, tasty! Great idea and successfully tested!!
I was skeptical when I first started reading your article. Less as I read it and started calculating too.
I calculate everything on my solar to amps and don’t normally think about the watts. So I also had to start doing the math. At first I said, “a heating element, no way”. So I had to drag out my slow cooker. While mine uses more power than yours (mine 190 Watts). You might get away with it. Mine, I don’t think so. At least not without sacrificing battery energy too.
For easy math lets use 100 VAC drawing 1 amps (100 watts) on the AC side of the inverter. For those that might not know the VAC closer to 110-120VAC.
The DC side of the inverter at 12VDC would be pulling roughly 9.2 amps off the 12VDC solar and/or batteries, to produce that 1 amp draw at 100VAC.
My 280 Watt system theoretically could produce about 15 amps per hour if everything were perfectly angled, and it was a mid summer day, clear sky day. I have seen 13, but depend on more like 10 amps per hour during the best hours of the day. That said, a 100 watt slow cooker pulling 1 amp at 100VAC (pulling 9.2 amps per hour on the DC side), the solar would just keep up (if producing 10 amps off the panels), with no negative draw from my battery bank.
In my case at nearly double the wattage rating on the slow cooker I would be drawing roughly 19 amps per hour. My panels don’t product that much even theoretically with perfect conditions.. I would be running about a loss of 9 amps over what I normally produce, per each hour of use. That additional energy would be pulled off the batteries.
In my case I have (2) 90 amp batteries. (180 amps total). Using the 50% discharge rule I do have 90 amps I could sacrifice from my battery bank. So even in my case, at twice the wattage on my slow cooker I could actually run it for several hours without discharging my batteries completely. I would just have to be more careful, and pick a real sunny day.
I may have to find a cooker with a lower wattage rating. Because now I want to try this.
Enjoyed your read,
I have one on solar if interested.
http://toponautic.blogspot.com/2015/05/solar-my-first-venture-into-building.html
Also an inverter calculator that some might find handy. http://toponautic.blogspot.com/p/calculator.html
Thank you for your thoughtful comment Rick. The Proctor-Silex 1.5 quart slow-cooker is very efficient. We did indeed cook the chili using solar power, but I wanted to share my figures so you know what the assumptions were. First of all, the slow-cooker has 4 settings off-warm-low-high, and they consume 0 – 35 – 65 – 95 watts respectively. I don’t have a 12-volt ammeter set up on the trailer, but I was able to make measurements with a Kill-a-Watt meter, so my figures are in 120 VAC and watt-hours.
Assuming we have cook times of 2 to 2 1/2 hours on high, and 8 to 9 hours on low, we get
95 watts * 2 hours = 190 watt-hours or 95 watts * 2 1/2 hours = 238 watt-hours — plus —
65 watts * 8 hours = 520 watt-hours or 65 watts * 9 hours = 585 watt-hours
This gives us a total of between 710 watt-hours to 823 watt-hours of power consumption.
Assuming an insolation of 5 (about right for Central Texas this time of year) and an inverter efficiency of 82% we get:
(823 watt-hours / 5) / .82 = 200 Watt estimated panel size
You’re right it’s a snug fit given our 200 watt panel size, and might use a little stored battery energy. Shorter cook times might result in a small surplus (e.g. 2 hours on low and 8 hours on high)
I looked at your “first-venture” post and there’s a lot of good information there. I can see you’ve been giving this a lot of thought. FWIW, I’m using two, HQST 100 watt flexible panels (mounted directly to the teardrop skin) and an inexpensive 30-amp PWM charge controller. There is one 80 AH Marine battery that I intend to upgrade before our next serious camping trip.
It looks like we have a similar approach: design using the best available numbers, then build it and learn something! I also think that’s the most fun. To that end, I’m in the process of installing a larger system to pump water here at the ranch, and you’re welcome to follow along (and keep me honest :-). There are a series of articles starting here: http://bit.ly/sprpstart
Also, one other resonance — I’ve spent a career in electronics and technology (amateur radio, TV broadcast, sound recording, IT)
Thanks again for your comment, and I’ll look forward to hearing about your adventures as well. — Jim