In comparing different types of solar cookers, the time needed to bring 1 liter of water (or oil) to 100° C is taken. In this test, box cookers generally show a poor performance compared to parabolic reflectors, as the rise of temperature above 70 ° C slows down in box cookers.
For practical usage this comparison is hardly relevant, as the optimal cooking process requires temperatures between 70 ° and 90 °. In addition, the cooking is already initiated during the heating phase below 70 °.
The preheated LAZOLA reaches (empty) temperatures above 160° C. Once food is placed within, the temperature falls markedly, but remains far above 70° C, depending on the amount of food and rises above 100° after some time.
In other comparisons, the energy input within a certain period of time is measured. This does not consider the fact that a large part of this energy is actually stored in the box due to the double glazing and the insulation of the inner box, whereas in the case of parabolic cookers a considerable part escapes to the environment again.
Particularly in the case of unstable weather conditions, the advantage of box cookers is evident: