solar cooking technology - how far are technology promoters and users from each other?

Box solar cookers studied in urban gujarat, india march-may 1999

In this article we take up the issue of use and disuse of box solar cookers by discussing some basic underlying assumptions of the technology as put forward (directly or indirectly) by technology promoter actors. we confront the assumptions with some practical realities that the users and disusers encounter when they practice solar cooking. in this way on the one hand some facts which have been instrumental for developing of the technology on the side of technology developers are opened up. and on the other hand related practical aspects of use and disuse are elucidated. the discussions hopefully will contribute to a better understanding of the users' real situations, and recognition of their role as an important technology actor.


a solar cooker is an alternative food cooking technology with sunlight as its only energy source. about 600,000 families have a solar cooker around the world, 400,000 of which are indian families. the indian families have procured their box solar cookers under a nation-wide solar cooking program. this program is one of the many national and international solar cooking projects implemented in sun-rich developing countries. what characterises the indian program however is that it has been running continuously during last not less than 20 years, in several states of india.

a box solar cooker is an insulated box of for example 50cm x 50cm x 15cm, with a glazed top window when put in sunshine it cooks rice, vegetable and chicken within 2-3 hours, a meal enough for a family of 5-6 persons. use of solar cookers are positively contributing to environment and conservation of resources. by using a solar cooker for lunch or dinner, a family can save up to 25% of yearly fuel budget. nevertheless most of these families have returned to conventional cooking methods after an initial use period of a month or two. to find out why and how the users discontinue use of their solar cookers i carried out a case study in gujarat, india, where the families spoke out about their daily days and experiences of solar cooking.

gujarat box solar cooker case study

gujarat is one of the richest states of india with about 40 million population located in the western part of india. in gujarat there is about 9 months of intense sunshine throughout the year. several kinds of foods including rice and dal (a kind of broken/split pea which is usually served with rice), which are most frequently served in gujarat can be cooked in a box solar cooker. gujarat state has carried out a steady solar cooker introduction, production and sale program during the 80's and 90's, which is still running. as a result of the program up to now about 45,000 locally produced solar cookers are sold to the urban and rural families. it is difficult to establish exactly how many of the solar cookers are used frequently and how many are not used, but several studies indicate that 50 - 75% of the families are disusers, and about half of the rest is using their solar cookers daily while the other half only use them occasionally. most of the indian box solar cookers are robust, and are functioning after several years after use. a solar cooker costs 750 indian rupees in gujarat with a payback time of no longer than 2 years, if used once a day. operation and maintenance of the solar cookers are not too demanding to the families. so the indian case studied here represents a case where disuse of solar cookers are minimally affected by external aspects of price, workability of solar cookers, operation and maintenance. as will be discussed, the constraints on use of solar cookers by wide number of prospective users are to be found in relation with use conditions of them by the users and disusers. this article is primarily based on findings from field studies i carried out in urban gujarat in india, where i asked the families why do you use/disuse your solar cooker. initially a pilot field study was carried out in 1997 and later during a detailed field study i interviewed 25 user and disuser families in three urban sites during the months of march, april and may 1999. in most of the interviews the wife, husband and the children took part. although the findings are directly relevant to box-type solar cookers in gujarat but in a wider sense parallels could be drawn to other solar cooker/cooking projects in general.

assumptions often put forward by technology promoter actors

among the very basic assumptions are:

  1. the prospective users are in possession of a sunny area to put their solar cookers.
  2. use of solar cooking in a box solar cooker is easy, time saving, and thus practical compared with cooking on fuelwood or gas.

the assumptions may seem convincing as they are pointing towards some very fundamental conditions; and if these conditions are not adequately fulfilled by a user, the user practically can not practice solar cooking. the study shows, however, that the assumptions do not catch the total reality of the conditions they are pointing towards. as a consequence, most of the prospective users turn back to conventional cooking methods.

solar cooking on the roofs, why and how?

let us take the first assumption of being in possession of a sunny area for solar cooking. in urban gujarat suitable solar cooking areas, as experienced by the interviewed families, are south facing open verandas, paved and wide frontyards and backyards and balconies. the families prefer these places as they are located near to the living room and the kitchen. we may bear in mind that population and housing density are high in urban india. and thus open areas like verandas and wide yards are not among common housing amenities. open and unpaved ground areas are not used for putting a solar cooker due to hazards of dust, damage by playing children, wandering animals and theft. most of paved backyards and frontyards are too narrow - located between neighbouring buildings - thus not having continued sunshine of for example three hours. some verandas and balconies have trees and high plants nearby, which cast shadow on their surroundings (trees and plants are usually planted and grown around the houses to protect against direct sunshine especially in the hot seasons). so a possible alternative place where many households can get access to durable sunshine, is the roof of their houses or apartments.

roof is a suitable place if we only consider availability of sunshine. in fact most of the users of solar cookers use their roofs for solar cooking. but roof too, is not a practical solution to every family. a problems is its distance from living room and the kitchen, and the fact that it requires going up and down. most of the disuser families visited, find it uncomfortable and sometimes impossible to cook on the roofs, especially if the roof is two floors or more above their living floor. this situation is considered extremely difficult for those in their 50s and up. common roofs suffer from the problem of being "insecure" - damage by others may happen to the solar cooker or the food. families usually do not leave their things unattendedi in common places for longer times and during nights. so the solar cooker used on common roofs should either be stored in a shed or store-room on the roof, or simply be carried back home after it is used for a session of cooking. and it should be taken again to the roof next day. most of the building blocks lack a shed/store-room on the roof. thus transportability of solar cooker, emerges as an important factor for solar cooking on common roofs. a new box solar cooker weighs 9 - 10 kg. (while the older ones weigh double as much). the ladies expressed that solar cookers are too heavy to be carried up and down. and the husbands often do not find daily transportation of solar cookers within their traditional family work-division and daily routine as such. therefore roof in our case is not a suitable place for solar cooking for considerably large number of families. to those living in detached houses and top floors of apartment blocks, roof could be a possible option.

in this way maybe the assumption that most of prospective user families have access to a sunny area is correct, but it is not correct to assume that the areas are suitable for solar cooking to all. it is difficult to say for what percentage of the families roof could be a possible option. however, it is clear that most families living in lower floors of apartment houses can not use their roofs for solar cooking. and a considerable part of common roofs are less appropriate for solar cooking because of being less secure and not having a convenient storing facility to store the solar cookers after daily use. to those living in detached houses and top floors of apartment blocks, roof offers an option ranging from less practical to practical, depending on the concrete situation of the family.

maybe easy and time-saving, but not practical to many

the second assumption asserts that solar cooking is easier and more time-saving than traditional cooking. the asserted ease and time-saving aspects of solar cooking means that when the raw food is put in solar cooker it does not require that the cook should continuously attend the cooking process. box solar cooker works as a hot oven and the glass window cover of the solar cooker is supposed to be kept closed throughout the cooking session. in other words the assertion implies that sun-cooking takes place more or less "by itself" within the solar cooker.

the assumption is among others related with the fact that sun-cooking is a slow-cooking method, with low degrees of cooker temperature of maximum 130(c (conventional cookers reach to 400 - 500(c and more); as a result of low-temperature cooking, the food will not be burnt and the person who cooks does not have to attend the cooker, and thus he or she will be in comfort and save time. but low-temperature cooking has other aspects, not readily obvious from the assumption, which are deemed impractical by many prospective users.

first solar cooking takes 2 - 3 hours which is 3 - 4 times as cooking with for example a gas cooker. thus cooking the lunch should start about 9 -10 o'clock in the morning, and supper should start early in the afternoon. to this we have to add about half an hour of preparation time before start of cooking: the raw food has to be cleaned, washed, peeled/cut, and seasoned before putting it in the cooker. but normally most of the families are doing other daily activities in morning and afternoon hours. in the morning about 9 - 10 o'clock when the raw food should be placed in the solar cooker, many families take breakfast, and afternoons between 13 and 16 o'clock are usually considered as resting time in the hot seasons. therefore, solar cooking implies changes in daily routine of the family, which is not an easy task to be implemented for many.

second low-temperature cooking means that the food is cooked by low-temperature steaming (in case of liquid foods like stew and rice) or low-temperature roasting (in case of dry items like peanuts) without possibility of regulating the heat. frying temperature can not be reached. some of the foods such as rice, dal, beans and some vegetables can be cooked in solar cooker, while other foods like chapati and bahkriii can not be prepared by solar cooker. therefore chapati or bahkri, one of which is served with every meal, has to be prepared by conventional cooking anyway. this reduces the above-mentioned ease and time saving merit of solar cooking to a certain degree. another related aspect is that during the 2 - 3 hours period of sun-cooking the person who cooks is not totally free-minded of solar cooker due to remembering and being at home (or instructing another member of the family for example) to change the direction of the solar cooker.

third an housewife who is an often-user of solar cooker is not less than an experienced cook; she considers some other things besides her normal cooking expertise when cooking. she for example includes the weather of the day (hot or less hot, sunny or less sunny) in her cooking planning of that day; takes into account the time interval between start of solar cooking and meal time; and accordingly for example adds the amount of food and water in the pots when putting them in the solar cooker. in this way compared with traditional cooking, solar cooking has less flexibility regarding cooking and cooking timing. a sun-cooking session from the time when the raw food is put in, up to the time the meal gets cooked, takes less efforts and time of the cook, however, solar cooking in itself, requires good and at times flexible cooking planning and preparation at the outset of a cooking session. the housewives with less possibilities and sense of adjustment would find solar cooking difficult to manage (here we do not mean cooking by solar cooker per se, but managing it as a food cooking option). for example young families with several and young children where food demand of the family is less likely to be harmonised regarding time of serving and type of food, are less capable of shifting to solar cooking.

furthermore taste, texture, and colour of solar-cooked food vary from those of prepared through traditional cooking methods. in the study, most gujarati housewives when asked "what is your bad experience with solar cooking" answered: "when i got bad food somehow someday". they even remembered when they had gotten uncooked, undercooked or over-cooked food. therefore the family should be ready to accept and adjust itself to changes in their cuisine and food taste if they should go for solar cooking.

to evaluate how practical box solar cooking procedure is, it thus becomes necessary to place it in a broader perspective. in other words low-temperature sun-cooking implies several changes on cooking procedure. therefore ease and time-saving are not the only changes but a part of a range of changes. generally many families do not find solar cooking well-fit with their daily routines, and the requirements of planning and certain cuisine adjustments are conceived less practical.


it was discussed that there is a considerable gap between the assumptions of technology actors on the one hand, and the real conditions of the daily days of users on the other. solar cooker technology promoters expect that at least a considerably large part of those who procure a solar cooker should shift to solar cooking for daily cooking. on the contrary only a small fraction turn to become often-users and the others return back to the traditional cooking methods after an initial short period of use. as argued above, this is mainly because the families often do not find use of their solar cookers practical in context of their daily days.

can we say then if a family has a comfortable sunny area for solar cooking and is able to arrange a daily routine compatible to solar cooking, would the family shift to solar cooking? the study shows that the above-discussed aspects of solar cooking are some conditional aspects which are important but not sufficient for a shiftiii. the aspects discussed, however, elucidate practice-related issues of solar cooking, and the gap between technology actors and users. this could be starting points for technology actors to investigate on and with their (prospective) users how technology could be shaped. to better ensure successful technological developments, closer dialogue with the users based on reflections between technology actors and the users of technology are called for.

i the families feel insecure to leave the cooker and food unattended because they fear that the food and/or the solar cooker might be damaged by playing children and by-passers.

ii chapati is thin round bread, and bahkri is a thicker round bread made of wheat dough. they are baked and/or fried in frying-pan on fire.

iii the discussed aspects are some basic conditional facts. the conditional facts met and accompanied with a genuine urge within the family (urge could result from need or pursue of a value) leads to use of solar cooker.

bashir ahmad
department of buildings and energy, technical university of denmark 20 november 1999

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