About one-third of the world’s population cooks by open fire or with inefficient stoves that use solid fuels or kerosene (WHO 2022). Household air pollution and high fuel costs are just a few of the serious problems associated with these methods. Solar cookers provide a safer and more sustainable option by harnessing the free, zero-emission energy of the sun.
California-based nonprofit Solar Cookers International (SCI) promotes the use of solar cookers where they can have the most value—in the “sun-rich, fuel-poor regions of Africa, Asia, the Pacific, and Latin America” (SCI 2018). Only 56% of people in Latin America and the Caribbean, 36% in East Asia, and 10% in sub-Saharan Africa have access to modern sources of energy for cooking (The World Bank 2020).
These households rely on burning wood, charcoal, coal, and kerosene, as well as crop residues and dung, not only to cook their food but also to pasteurize their water so it’s safe to drink. While the high cost of fuel can be alarming—equal to 30% to 50% of a poor family’s income in some urban areas (SCI 2004)—the health impacts are perhaps more so.
Exposure to household air pollution is linked to ischemic heart disease, stroke, chronic pulmonary disease, and lung cancer and is responsible for an estimated 3.2 million deaths annually (WHO 2022). Women and children are the most likely to suffer since they spend more time inside the home. They typically also bear the burden of collecting firewood, which can be time-consuming (requiring traveling long distances by foot) and dangerous (increasing their risk of assault) (WHO 2016).
Solar cookers are a safer, cleaner, and low-cost alternative to these traditional cooking methods and can even be built at home. While there are many designs, three of the most common types are the box, the parabolic, and the panel cooker.
The box cooker (or solar oven) is typically a wooden box with a transparent plastic window on top and an aluminum foil–lined lid that is propped open to direct the sunlight. The interior sides and bottom of the box cooker are lined with a dark material to trap the heat and cook the food inside.
The parabolic cooker, which looks like a large reflective bowl, focuses the sunlight directly onto a matte black pot placed in the center. This design achieves higher temperatures (and is even able to fry foods), so it must be monitored to avoid burning, with the user adjusting the angle as needed.
The panel cooker combines elements of both designs and is the easiest to make, requiring only cardboard and aluminum foil. The aluminum foil–lined cardboard is bent into reflective panels to partially surround the pot, and there may also be a transparent enclosure to help retain the heat.
While some solar cookers can reach 300°F or higher, a unit’s maximum temperature depends as much on its design as its construction. In addition, adverse weather conditions such as wind, rain, and low sunlight can hinder efforts to cook with a solar cooker.
One recent initiative brought solar cookers to the Kakuma Refugee Camp in Kenya—an area whose high insolation values (a measure of solar radiation delivery per unit of surface) make it well-suited for solar technologies. With SCI’s support, Kenyan residents constructed 234 box cookers from local materials for Kakuma families (SCI 2021).
Besides providing refugee families with cleaner household air and increased safety for women and children, these solar cookers are expected to prevent 5,229 metric tons of CO2 emissions over the units’ lifespan of 15 years (SCI 2021).ft