Storing cooking fuel for various situations such as electricity outages is one of the weakest parts of my preparedness plans. I currently store and rotate through multiple large canisters of propane for use with my grill. I have plastic buckets full of charcoal for my dutch oven and apple-box oven. But there are limits on how much propane I can legally store. And I can't possibly store large enough quantities of charcoal. So, I've been exploring the merits of solar cooking to expand my options.
There are a lot of commercial products available for solar cooking. Unfortunately these products are often quite expensive. The amazing thing I've discovered, is that you can often get the same results with as little as $3 and not much more work on your part.
I want to direct you to two fabulous sites on solar cooking. Both sites have resulted from efforts to improve cooking situations for women in Africa and South America. The first is a wiki (http://solarcooking.wikia.com/wiki/Plans) with many solar cooking designs. It includes plans for elaborate solar cookers to simple homemade solar cookers that can be just as or more effective.
This second site (http://solarcooking.org/plans/funnel.htm) gives the plans for an effective solar stove developed by Dr. Steven Jones, a BYU physics professor. The part I love most about the link on Dr. Jones' page is that he includes a chart with estimated cooking times (it is about 3/4 down the page).
Here are two other links by Dr. Jones on solar cooking (for some reason this site is not easily navigable):
My favorite? The Windshield Shade Solar Cooker developed by Kathy Dahle-Bredine (found on the Solar Wiki). This cooker is almost identical to Dr. Jones' design except it uses a reflective windshield shade instead. I'm eager to have something that can withstand water a bit better than Mylar-covered cardboard, so this is the design I've opted to pursue.
Making one of these solar cookers is my current project right now. I've already been to my guaranteed-to-have-one-of-everything store with a list of products. Unfortunately they didn't have the one fundamental item that I needed - the reflective windshield shade. So my next try will be at an automotive shop. I already have cooking bags and cooling racks on hand. I'm also looking for a black pot for under $10 that is approximately 5 quarts or less. I've seen a 7.5 quart pan for $12, but it seems too big. The cheapest "pan" option is actually a black-painted canning jar. I'd prefer something a little more durable if possible, but I am intrigued by the "pressurizing" potential when using canning lids (see Dr. Jones' design).