Method of testing durability of CIS based thin-film solar cell module
The property of CIS based thin-film solar cell modules that the modules recover their conversion efficiency, etc. upon irradiation with a weak light is correctly evaluated. A CIS based thin-film solar cell module is subjected to a conventional damp heat test with a constant-light solar simulator (solar simulator) 1 D in such a manner that the power of the light source 1 E is regulated so that the solar simulator 1 D emits a weak light corresponding to the amount of solar radiation in cloudy weather, i.e., resulting in an irradiance of 100-300 W/m 2 , and the module is continuously irradiated with the weak light throughout the test period under the same temperature, humidity, and storage period conditions as those in the conventional conditions for the test (1,000-hour storage in the dark at a temperature of 85° C. and a relative humidity of 85%). Thus, the property of the module 2 ′ that the module 2 ′ does not show considerable deterioration even after storage in an open state for 1,000 hours can be correctly evaluated.
1. An improved method of testing the durability of a CIS based thin-film solar cell module, which is a durability test method capable of correctly evaluating a property of a CIS based thin-film solar cell module that the module recovers its conversion efficiency upon irradiation with a weak light,
wherein a CIS based thin-film solar cell module whose durability is to be tested is subjected to a damp heat test which is a test in which a sample is stored in the dark for 1,000 hours under the relatively high-temperature high-humidity conditions of a temperature of 85° C. and a relative humidity of 85%, and that in conducting the damp heat test, the power of a xenon lamp is regulated so that the constant-light solar simulator (solar simulator) emits a weak light corresponding to the amount of solar radiation in cloudy weather and the module is continuously irradiated with the weak light throughout the test period under the same temperature, humidity, and storage period conditions to determine various solar cell characteristics, and
wherein the module is irradiated with the weak light at an irradiance of 100-300 W/m 2 .
2. The improved method of testing the durability of a CIS based thin-film solar cell module according to claim 1 , wherein the CIS based thin-film solar cell module comprises a CIS based thin-film solar cell submodule obtained by electrically connecting a plurality of CIS based thin-film solar cell devices by patterning, a cover glass bonded to the submodule through a thermally crosslinked EVA resin film as an adhesive, a back sheet bonded to a back-side glass substrate of the submodule through a thermally crosslinked EVA resin film, a cable-possessing connection box disposed beneath the back sheet, and a frame attached to the periphery of the resultant structure through a sealing material,
wherein the CIS based thin-film solar cell devices each being a pn heterojunction device of a substrate structure which comprises a glass substrate and high-quality thin layers composed of an alkali barrier layer, a metallic back electrode layer (generally molybdenum), a p-type CIS light absorbing layer, a high-resistance buffer layer, and an n-type window layer (transparent conductive film) which have been superposed in this order on the substrate,
wherein the light absorbing layer is constituted of a multinary compound semiconductor thin film and made of a p-type semiconductor.
3. The improved method of testing the durability of a CIS based thin-film solar cell module according to claim 2 , wherein the p-type semiconductor is a I-III-VI 2 Group chalcopyrite semiconductor.