Page 86 - Solar Power in Building Design The Engineer's Complete Design Resource

56 SOLAR POWER SYSTEM DESIGN CONSIDERATIONS

battery technology, this section covers the physical and chemical principles, manufac-
turing, design application, and maintenance procedures of the storage battery. In this
section we will also attempt to analyze and discuss the advantages and disadvantages
of different types of commercially available solar power batteries and their specific
performance characteristics.

HISTORY

In 1936, while excavating the ruins of a 2000-year-old village near Baghdad, called
Khujut Rabu, workers discovered a mysterious small jar identified as a Sumerian artifact
dated to 250 BC. This jar, which was identified as the earliest battery, was a 6-in-high
pot of bright yellow clay that included a copper-enveloped iron rod capped with an
asphalt-like stopper. The edge of the copper cylinder was soldered with a lead-tin alloy
comparable to today’s solder. The bottom of the cylinder was capped with a crimped-in
copper disk and sealed with bitumen or asphalt. Another insulating layer of asphalt
sealed the top and also held in place the iron rod that was suspended into the center of
the copper cylinder. The rod showed evidence of having been corroded with an agent.
The jar when filled with vinegar produces about 1.1 V of electric potential.
A German archaeologist, Wilhelm Konig, who examined the object (see Figures 3.6
and 3.7), came to the surprising conclusion that the clay pot was nothing less than

Figure 3.6 The Baghdad battery.