Heat-pipe technology was borrowed from rudimentary heat-conducting pipes used by English bakers 100 years ago.From http://www.thermomax.com/Downloads/Vacuum Tube Paper.pdf:
Heat pipes vary greatly in size, depending upon their particular use. Some are the size of hypodermic needles, while larger versions stretch to 24 feet.
... miniature heat pipes ... cool the chips inside most laptop computers.
Heat pipes work efficiently in a zero-gravity environment; commercially developed heat pipes are now routinely used to cool electronics in communications satellites.
Modern heat pipe technology was first developed at Los Alamos nearly 40 years ago. Engineer George Grover, who did much of the pioneering and theoretical work on heat pipes at Los Alamos, demonstrated the first heat pipe in 1963.
... A lithium heat pipe developed at Los Alamos in the mid-1980s transferred heat energy at a power density of 23 kilowatts per square centimeter. To put this figure in perspective, heat is emitted from the sun's surface at six kilowatts per square centimeter.
The mass production of fluorescen[t] light bulbs set a precedent for the tubular solar collector design. Building a tubular evacuated solar collector and maintaining of its high vacuum, similar to light bulbs and TV tubes, is a well-established production process.From http://www.solar-rating.org/solarfacts/energyproduction20011017.pdf
A typical residential solar water heating system (SWHS) for a family of four delivers 4 kilowatts of electrical equivalent thermal power when under full sun and when the temperature of the water in the storage tank is about the same as the air temperature. Such a system typically has about 64 square feet of solar collector surface area and produces approximately the same peak power as 400 square feet of photovoltaic panels.and
... a typical SWHS contributes 7 to 10 kilowatt-hours per day, depending on the solar resource and type of collector. Electric water heating for residential applications typically consumes about 12 kilowatt-hours per day, depending on ground water temperature.