Our heat demand is often underestimated. If you want to deal with the generation of solar energy, you will be happy to consider a solar grill. (kWh to Heat online Calculator)
Of course exactly the contrary trend to the cheap charcoal from virgin forests, for ever larger and monstrous Grill ever larger mountains of meat. This is the reason why such a barbeque in the park, beach, at the party or at the festival for a great look.
In the case of solar grills and ovens it is necessary to collect food without firewood. In particular, for women sometimes a dangerous activity. Collecting firewood can also be fun and is a nice pastime like Mark Boyle explained it to us. In contrast, without flame and smoke cooking can be healthier and safer for toddlers or a highly flammable environment (the vacuum tubes insulate the heat to the outside).
The parabolic cookers, which have been known since ancient times, are often difficult to transport and in necessary of cookware. Not so with the more modern vacuum tubes.
I have looked at the specifications and details of two of the largest manufacturers and compared their maximum cooking volume in the tube:
Kugel und Zylinder und Quader Oberflächen und Volumen online Rechner
Kugel Oberfläche: 4*Pi*r²; Zylinder: 2*Pi*r² + 2*Pi*h;Quader: 2*a(r)*b(h)+2*a(r)*c(t)+2*b(h)*c(t)
Kugel Volumen: 4/3*PI*r²; Zylinder: Pi*r²*h;Quader: a(r) * b(h) * c(t)
The solar Griller from the USA has much less volume for the same price. What I also miss with the manufacturer from the USA is the information from where the energy comes for production. From Huang Ming to the head of Himin, I have been able to convince myself on the spot. Since he is a connoisseur of Austrian wine, I already have a few glasses with him about the sustainability strategy for his region and he supplies with the generated energy more than just his production.
The horizontal use is beneficial for dry food. If I want to make soups or hot drinks like tea and coffee, I would at least have the option to have the Griller to operate vertically. Himin is also supplied with a special retractable glass container.
Just boiling water can be an essential function of solar cookers. At Go Sun, I can not say whether an internal glass tube protection is supplied from metal, which can also be used for this purpose. Himin is supplied with such a glass tube protection.
If you want to take a picture yourself, I rent Solar BBQ Griller from Himin and other manufacturers in different sizes.