A device for the conversion of solar energy into electrical energy is proposed.
The device is a two-stage process with the first stage being the conversion of solar to chemical energy and the second stage being the conversion of chemical to electrical energy.
The solar energy is stored by means of the photochemical isomerization of trans to cis organic acids.
Because of differences in solubility and ionization constants, cis-acid solutions have a higher concentration of hydrogen ions than do trans-acid solutions.
Because of the difference in hydrogen ion concentration, electrochemical concentration cells can be constructed from cis and trans acid solutions; and thereby a portion of the chemical energy can be recovered as electrical energy.
Concentration cells using cis and trans acids were constructed and potentials approaching the theoretical values of approximately 0.1 volts were measured.
These cells possessed internal resistances of order of 1000 ohms. Despite this, the maximum electrical power measured in the various systems, was between 2 and 3 microwatts/cm2 of electrode area. Techniques for reducing the internal resistances are being investigated.
The maximum electrochemical efficiencies of the concentration cells are good and while the photochemical efficiencies are not calculated, it is anticipated the overall efficiency of the device will be reasonably good.
The proposed cell should provide an efficient means of utilizing the free, infinite source of energy from the sun with the advantage over other solar conversion techniques that it serves as its own storage battery.