Performance of Photovoltaic Cells in Undersea Environment

Abstract

Photovoltaic solar cells can serve as a reliable source of electric power for electronic instrumentation in temporarily or permanently submerged marine systems in the form of bottom installations, buoys, or remotely controlled unmanned vehicles. The power output of submerged solar cells is a function of solar insolation intensity on the water surface, depth of submersion, optical properties of water, temperature, and the orientation of the cell surface with respect to the sun. Experimental data was generated by submerging solar cell panels in different bodies of water with 2.5 to 95 feet (0.75 to 29 meters) visibility range, as defined by the observation of a submerged standard 12-inch Secchi disc, and measuring their performance under load. The power output of horizontally oriented, upward facing, photovoltaic cells submerged to the visual contrast limit/depth was found to be a constant, equal to approximately five to ten percent of the power generated by upward facing horizontally oriented cells in atmospheric environment. At lesser depths, the power output of the cells increased, until in the splash zone the output was essentially the same as in atmospheric environment. Based on these findings it can be concluded that high efficiency silicon solar cells can serve as a practical electrical power supply in electronic devices for marine applications, providing that their depth of submersion is less than the visual contrast limit at the dive location.

Analysing consequence of solar irradiance on amorphous silicon solar cell in variable underwater environments

“…Initially, the solar radiation above the water surface is maintained 1000 W/m 2 as per Standard Test Conditions (STC), which is considered as 0 m, its changes were measured with an increase in depth of the water up to 0.2 m, and the corresponding I ‐ V and P ‐ V curves were also obtained using the source meter. The Solar radiation underwater starts decreasing with an increase in depth of the water, as shown in Figure D because of the changes in solar spectrum underwater . Figure A,B shows the behaviour of I ‐ V and P ‐ V curves for an amorphous silicon Solar cell underwater with respect to the water depths up to 0.2 m. These I ‐ V and P ‐ V curves show linear behaviour because the water is stable and turbulence‐free.…”

“…Even though this is very low, but is high enough to power the submerged marine electronic devices. 4 Currently, all these systems are conventionally powered from batteries, onshore power sources, etc, but, undoubtedly, solar PV underwater can be a strong contender to power them with modern electronics. 5 Recently, US Naval Research Laboratory manifested that by using high bandgap energy, solar cell can harvest the useful power underwater.…”

“…The Solar radiation underwater starts decreasing with an increase in depth of the water, as shown in Figure 8D because of the changes in solar spectrum underwater. [2][3][4][5][6][7] Figure 8A,B shows the behaviour of I-V and P-V curves for an amorphous silicon Solar cell underwater with respect to the water depths up to 0.2 m. These I-V and P-V curves show linear behaviour because the water is stable and turbulence-free. The decrease in the I-V and P-V curves with the depth of the water was mainly due to a decrease in Solar radiation underwater.…”

“…The measurement of solar radiation underwater by a silicon solar cell undergoes two main effects such as the water‐cell interface and the spectral changes with water depth . About 40 years ago, Stachiw performed a direct experiment on the photovoltaic undersea environment. The power output of Solar cells depends upon the amount of Solar radiation, optical properties of water and temperature, etc.…”

“…When the ocean surface is at 100 mW/cm 2 insolation, only 5% of power output is generated from the Solar cell at visual contrast limit depth. Even though this is very low, but is high enough to power the submerged marine electronic devices . Currently, all these systems are conventionally powered from batteries, onshore power sources, etc, but, undoubtedly, solar PV underwater can be a strong contender to power them with modern electronics …”