Fast series resistance imaging for silicon solar cells using electroluminescence

Abstract

We introduce a fast and easy to apply method for determining the local series resistance of standard silicon solar cells. For this method only two electroluminescence images taken at different voltages are needed. From these two images, the local voltage and the local current density through the device can be calculated. Knowing these parameters for each pixel yields the local series resistance. By calculating the cell's dark saturation current from the lower voltage image, the method also works with multicrystal line material. We show images, acquired in only 300 ms and compare them with other luminescence based series resistance images

Local analysis of the efficiency of solar cells based on dark lock-in thermography imaging

“…This image may be measured e.g. by photoluminescence or electroluminescence imaging [3,4] or by applying the so-called RESI method [5]. Alternatively, if the evaluation is made at relatively low voltages, where a low current is flowing and the voltage drop is weak, the series resistance also may be assumed to be locally constant.…”

“…This allows to calculate for all biases the local voltage images according to V loc = V B -R s (x,y)J(x,y), see (2). Now the four unknown diode parameters are obtained for each position by applying a special iterative procedure described in [2], which fits in each position (x,y) the four J(V loc ) data pairs of the four voltages where the LT images have been taken to the two-diode model (4). Once the four diode parameters J 01 , J 02 , n, and R p are calculated for each position (x,y), and R s (x,y) is known, the solar cell is completely locally characterized.…”

Testing and failure analysis of thin film solar cells

“…Additional electrical conditions have to be taken into account when EL results are compared with PL due to local resistivity variations or band population differences due to electrical fields etc. [17][18][19]21]. A further technique using RR is cathode-luminescence (CL) with excess carriers produced …”

Selective Chemical Etching for Studying the Front Side Contact in Thick Film Screen Printed Crystalline P-Type Silicon Solar Cells

“…The same device allows for measuring the line resistance of the contact. Spatially resolved imaging based such as electroluminescence (EL) and photoluminescence (PL) are used both to generate a map of the recombination and the resistive losses in a solar cell 22,23,24 . An illumination level dependent open circuit voltage (SunsVoc) device can be used to measure leakage currents (also called shunting) 25 .…”