Large area module performance and identification and control of p-i interface-correlated device degradation and further improvement in stabilized efficiencies of single-junction a-Si solar cells

On a large scale, APS' PVUSA array has been in operation for two years now and continues to produce power in excess of its original specifications. Its output measured in October 1994 was 423 kW/sub AC/. On a laboratory scale, in the last IEEE PVSC we reported our progress in improving the stability of a-Si based solar cells and in establishing 7.7% stabilized efficiency in single-junction devices. The best of these devices had a relatively low Voc of about 0.8 volts. By further optimization of the p layer, and p-i interface we have produced single junction devices with 0.86 volt Voc and 8.5% stabilized efficiency. Stable output in these devices was obtained after a very brief, 10 hour light soak.