Engineering topics

Burgess, E. L.

Publications and source records attributed to Burgess, E. L..

3 records

NASA NTRS1979

Application of the superposition principle to solar-cell analysis

The superposition principle of differential-equation theory - which applies if and only if the relevant boundary-value problems are linear - is used to derive the widely used shifting approximation that the current-voltage characteristic of an illuminated solar cell is the dark current-voltage characteristic shifted by the short-circuit photocurrent. Analytical methods are presented to treat cases where shifting is not strictly valid. Well-defined conditions necessary for superposition to apply are established. For high injection in the base region, the method of analysis accurately yields the dependence of the open-circuit voltage on the short-circuit current (or the illumination level).

Lindholm, F. A.↗

NASA NTRS1976

Silicon solar cell testing in concentrated sunlight and simulated sunlight

A method is described for testing silicon solar cells in concentrated sunlight and simulated sunlight. Concentrated sunlight is obtained by using an acrylic Fresnel lens; the simulated sunlight source is a short arc Xenon lamp. Average illumination levels during the tests are inferred from an assumed linear relationship between short circuit current and illumination. The linearity assumption is investigated for 0.3 alpha cm base resistivity silicon cells and found to be valid. Some typical results are presented to illustrate the type of information obtained during the testing.

Burgess, E. L.↗

NASA NTRS1976

Basic corrections to predictions of solar cell performance required by nonlinearities

The superposition principle is used to derive the approximation that the current-voltage characteristic of an illuminated solar cell is the dark current-voltage characteristic shifted by the short-circuit photocurrent. The derivation requires the linearity of the boundary value problems that underlie the electrical characteristics. The shifting approximation is invalid if considerable photocurrent and considerable dark current both occur within the junction space-charge region; it is invalid also if sizable series resistance is present or if high-injection concentrations of holes and electrons exist within the quasi-neutral regions.

Lindholm, F. A.↗