lowered to different depths at various locations and their power output was monitored by 

 electronic instrumentation. The objective of this exploratory field study was to establish a 

 first-order empirical relationship between solar cell performance and its operational depth. 

 To make the exploratory study practical, the optical properties of water were measured with 

 a simple Secchi disc, which defines underwater visibility in terms of contrast-limited range. 



Measurement of the power output by the two solar cell arrays fabricated for this 

 purpose was first performed under laboratory conditions in air at the test facilities of the 

 fabricator, Solarex, Inc. To define the baseline performance of the two identical solar cell 

 arrays, their potential and current outputs were measured under artificial sunlight whose 

 intensity was varied from 1.0 to 0.01 standard suns at ambient temperatures from 2 to 71°F 

 (figures 7, 8, and 9). These plots of potential as a function of current (VI plots) show that 

 the current output of the solar array is directly proportional to the light intensity, if the 

 spectral composition of the light remains approximately the same. The potential at which 

 the maximum power output was observed remained essentially the same through the entire 

 range of variations in sunlight intensity. As the ambient temperature decreased, the maximum 

 current decreased, the maximum potential increased, and the maximum power (product of 

 current and voltage) increased. Thus, it could be concluded that these solar cell arrays were 

 well suited for undersea applications, as water cooling increased the maximum power output 

 and the relationship between the maximum power output and the solar light intensity 

 remained linear even at 1 percent of standard sun insolation. 



12 



