Solar energy-to-electricity conversion efficiency

Solar energy-to-electricity conversion efficiency (rf) under white-light irradiation (e.g., AM 1.5) can be obtained from... 

Koyama has examined the sensitization behavior of a series of pheophorbide sensitizers (112-117) with similar structure. The results indicate that the short-circuit current density as well as the overall solar energy-to-electricity conversion efficiency increased with the increasing Qy absorption and with the decreasing one electron-oxidation potential. Two empirical models are built based on the experimental results. One model suggests a parallel electron injection from both excited and ground states to the conduction band of Ti02 whereas the other one supports an electron injection via the excited state only, in which both the Qy absorption and the Qy-state one electron-oxidation potential can contribute [110]. 

Heat engines for conversion of solar energy to electric power ideally should have lhe following attributes (1) low cost per kilowatt output capacity (2) long life and reliable operation with minimal maintenance (3) safe and environmentally acceptable operation (4) characteristics compatible with cycle top temperatures up to 1,000 K and (5) efficiency approaching Carnot values. 

Therefore, it is anticipated that this initial project will lead to broader social and environmental advances and act as a model for further cogeneration plants. Conversion of hydro, wind and, solar energy to electricity and to hydrogen will open a new venue for the efficient utilization of renewable energy resources in Azerbaijan. 

Discovery of amorphous silicon and its dopability has already had a tremendous impact on industrial applications of amorphous materials. Amorphous Si is now used fairly extensively as a photovoltaic material. In photovoltaic applications, solar photons excite the electrons across the gap and the resulting electron-hole pairs, are driven towards the respective electrodes in order to prevent their recombination. Electron is driven through an external resistance to generate the electrical power. The efficiency of conversion of solar energy to electrical power is characterized by an efficiency factor, r, which is given by. 

The multiple band gap solar to electrical conversion efficiency of 19.2% compares favorably to the maximum 15 to 16% solar to electrical energy conversion efficiency previously reported for single band gap PECs [9, 10]. Small photoelectrochemical efficiency losses can be attributed to polarization losses accumulating at the solution interfaces. Under illumination, a photocurrent density of 13 mA cm seen in Fig. 7 is consistent with polarization... 

The Fig. 12 inset contains the Eq. (18)-determined ]electrolysis- The limiting maximum photoelectrolysis can be readily determined from the solar to electrical conversion efficiency. Expanding Eq. (15) with Eq. (18), photoelectrolysis is diminished from Tjphoto l y the potential of the stored energy compared to the potential at which the water electrolysis occurred ... 

In 1976, the first regenerative PECs with substantial and sustained solar to electrical conversion efficiency were demonstrated. These PECs are based on n-type cadmium chalcogenide (S, Se or Te) electrodes immersed in aqueous polychalcogenide electrolytes. The cells were introduced by Hodes, Cahen, and Manassen (31), Wrighton and coworkers [32], and Heller and Miller [33] and were capable of converting up to 7% of insolation to electrical energy. Most investigations of these systems focused on solid-state and interfacial aspects of these PECs and photodriven oxidation of polysulfide at the photoelectrode was represented ... 

Along with conventional parameters constraining photovoltaic devices, modification of the electrolyte (solution phase) chemistry is a key to understanding the mechanism of energy conversion and device characteristics of PECs. The fundamental importance of modification of the electrolyte in terms of the distribution of species in photoelectrolytes and the pragmatic importance in terms of enhanced solar to electrical conversion efficiency is reiterated by studies... 

---