The paper describes the progress and current status of BP Solar's prog
ramme on Apollo thin film CdTe modules. It covers the latest improveme
nts in process yield and module reliability, and discusses recent resu
lts from investigations of the semiconductor material properties. Resu
lts show that more than 90% of the solar cells are produced with effic
iencies above 8% on 300 mm X 300 mm low cost substrates where the tin
oxide has been deposited on the float glass line. In addition to the s
ingle plate modules, multiplate modules incorporating six plates in a
3 x 2 format under a monolithic front glass sheet have been fabricated
with aperture area efficiencies up to 7.8%. The reliability of module
performance has been assessed using environmental tests based on the
CEC Specification 701 for thin film modules. The efficiency stability
of the modules is measured outdoors in Spain by automatic monitoring o
f current-voltage characteristics and indoors with an accelerated test
. Results of both tests show stable module efficiencies above 8.0%.