Page 207 - A Comprehensive Guide to Solar Energy Systems

Chapter 9 • Crystalline Silicon Solar Cell and Module Technology 209

The PV modules usually may have a long-term power output degradation rate of be-
tween 0.3% and 1.0% per annum. For c-Si modules, a generic degradation rate of 0.4%
per annum is usually considered acceptable. Power degradation over time is warranted by
the manufacturers as a service time, that is, time period between starting operation and
decreasing output power below 80% of the nominate value. At present, the service time
of c-Si modules with polymer back sheets is 25 years and over 30 years for modules with
glass–cell–glass structures.

9.6 Conclusions

The production processes in the solar industry still have great potential for technology
optimization. Wafer-based c-Si technologies are the workhorse of the current PV power
generation. This has been achieved by the combination of increased cell and module per-
formance in conjunction with significantly reduced manufacturing costs, especially at the
cell and module level, by the efficient use of Si and non-Si materials. In 2016, the crystalline
Si wafer-based PV technology accounted for approximately 94% of the total production
that was nearly 82 GW p (c-Si: 77 GW p ; thin film: 4.9 GW p ) [46]. Today, mc-Si modules domi-
nate the market; in 2016, its share of global production was nearly 70% (Fig. 9.30). Fig. 9.30
also demonstrates the present dominancy of wafer-based c-Si technology over thin film
technologies. It is predicted that in the future there will be a shift toward mono c-Si cells
[4]. Present developments in c-Si technology are driven by efficiency improvements, inte-
grated factories scaling up processes providing more efficient production processes, and
improvements in supply chain management. Over the past 10 years the efficiency of aver-
age commercial wafer-based silicon modules has increased from approximately 12% to
17% and modules based on IBC technology with efficiency 22% are now available on the
market.

FIGURE 9.30 Technology distribution in 2016.