How much food can a SUNSPOT™ cook?
The base model SUNSPOT™ will support an electrical load of 2 kilowatt hours per day, which is typically enough to cook basic meals for a family of five to six people, plus enough electricity to power lights and charge mobile phones. We have done testing of different types of basic cooking and will be posting results on the blog.
For example, Zambian nshima (cornmeal porridge) and ndima (greens) used about 0.8 kWh. Haitian rice and beans plus a sauce used less than 1 kWh. A pork, eggplant and leek stir fry with rice used just over 0.5 kWh. Tarka dhal with dry fried curried cauliflower & potatoes plus rice used 1.2 kWh.
Can I cook at night with a SUNSPOT™?
The SUNSPOT™ has a battery, but it is relatively small and is intended mostly to balance the solar output and cooking needs. It is most efficient to cook during the day (afternoon / early evening is fine) and use the system for lighting at night.
Will a SUNSPOT™ come in different sizes?
We are currently developing field trials to validate our assumptions about how much energy a typical household needs to cook basic meals, which drives the decisions on how to size the systems. Initially the unit will follow Henry Ford’s famous maxim (“It comes in any color you want as long as you want black…”) and have one size, but it is likely that we will eventually expand this.
Does a SUNSPOT™ work with a microgrid as well?
Induction cooking is actually a great load for a microgrid, as long as the designers include some sort of planning for balancing the usage to make sure that everyone doesn’t turn their stoves on high at the same time. Fortunately, most cooking uses a short period of high heat to bring water to a boil, followed by a longer period of simmering at low power, so this should be manageable. You don’t need a SUNSPOT™.
We are also looking at a design which keeps the batteries but uses the grid to recharge them rather than solar. This could be useful in areas that have electricity, but delivery is not reliable (weak grids).
Where can a SUNSPOT™ be used?
The SUNSPOT™ can be used anywhere there is sunshine. The solar output will vary by season (summer / winter, dry season / rainy season) so there are times when it will still be necessary to use a wood or charcoal stove, but the SUNSPOT™ should provide the vast majority of energy needed to cook over the year.
If you have questions about a specific site, you can use programs such as NSolVx (www.nsolpv.com) to calculate specific performance. We can provide a base PV7 design file that you can use to calculate performance in different locations.
How does a SUNSPOT™ compare to those solar cookers that use giant reflectors?
SUNSPOT™ uses “solar electric” power, also called “photovoltaics” or simple “PV.” A PV module converts the light from the sun into electricity, which is used to power the stove or is stored in a battery for later use. The systems with the giant mirrors use “solar thermal” power to concentrate the sun’s rays to heat up a surface or pot. This method requires clear skies (concentrating solar will not work if it is hazy or cloudy) and also requires moving the mirror throughout the day so that it stays aimed at the sun. There is no storage in the system, so you have to cook when the sun is out (starting by nine o’clock in the morning) or you will not get enough energy to finish cooking. And it is more difficult to power lights or charge a mobile phone using a solar thermal cooker.
How does a SUNSPOT™ compare to an “Improved Charcoal Stove” such as a Jiko?
While an “improved wood/charcoal cookstove” is a great improvement over the traditional three-stone fire, it still requires purchasing fuel and it still releases significant amounts of smoke, carbon monoxide and other harmful pollutants. The SUNSPOT™ eliminates all air pollution and gets rid of the open flames and hot surfaces which can cause burns and house fires.
The induction stove is “instant on/off” --no startup time or wasted fuel after the cooking is finished. This also allows changes in cooking patterns. It is much easier to heat a pot of tea or boil some eggs using a SUNSPOT™ than with any type of biomass cookstove.
How much will a SUNSPOT™ cost?
Our goal is for the SUNSPOT™ to cost less per month (using Pay-As-You-Go financing) than the traditional household expenditures for wood/charcoal plus a small solar-home system to provide electricity for lighting and mobile phone charging. In areas that still rely on wood collected from nearby forests, a performance-based social subsidy may be required to bring the costs down so that these households can get the benefits of improved health and safety from using a SUNSPOT™.
Does a SUNSPOT™ emit CO2?
The UN estimates that three billion people still cook with biomass worldwide.
According to THE CHARCOAL TRANSITION: Greening the charcoal value chain to mitigate climate change and improve local livelihoods, FAO/UN, Rome 2017
“An estimated 1–2.4 Gt CO2e of greenhouse gases are emitted annually in the production and use of fuelwood and charcoal, which is 2–7 percent of global anthropogenic emissions.”
The report goes on to recommend how to achieve reductions through more efficient charcoal kilns and wood/charcoal cookstoves.
While the SUNSPOT does not emit any CO2 during use, it does have a "CO2 footprint" due to manufacturing and transport of the materials used to construct the system. The equipment also has an "environmental footprint" and it will be important to collect and recycle as much of the equipment as possible (especially batteries, which contain lead, and PV modules) at end-of-life.
Obviously, this is a huge challenge, but also an opportunity to improve peoples lives and health while simultaneous helping the environment.
Can I order a SUNSPOT™ now?
Not yet. We want to make sure that the product will be robust enough to survive village conditions and will provide enough power to cook all meals for the target households.
If you are interested in funding a pilot project, contact us and we will be happy to talk.