AUTOMATION
typically supply raw material data and receive data
from the MES system such as consumed raw
material, produced volumes, quality, intermediate
products and inventory. These types of data will
usually be used for accounting purposes in the
ERP system. System integration, data collection
and tracking are fundamental to get the most out
of a MES system. It is therefore of utmost
importance to invest sufficiently of time and money
in a good data acquisition backbone.
MES use for daily operation
In modern PV, the MES system is used to monitor
and visualise process operations, resulting in
better control over the production process and
thereby higher yield and product quality. Some essential to the early cash-flow. An MES system Fig 2: Manufacturing flow
examples of such continuous monitoring and will greatly increase the ramp-up speed by for PV manufacturing.
control functionalities are: allowing faster identification of sources for Device manufacturing
generating off-spec products. It is therefore
ring6 Ensuring that only bricks that have passed extremely important to get the MES system up and
quality control with a lifetime measurement can running prior to plant startup. The MES system will
be registered into a wafer saw. be a key tool for identifying obstacles to reaching
ring6 Showing percentage of wreckage from a cell production targets. When the plant is up and
printing line in a real-time chart. running, the MES system will continue as an
ring6 Giving a real-time overview of total production important tool for continuous process optimisation.
line with drilldown possibilities.
ring6 Showing real-time SPC charts to ensure correct In the race to reach grid parity, process
37
operation of production line or sub processes. improvements are frequently introduced. In this
race the MES system is important for finding
www
ring6 Showing status, alarms and key performance
indicators. optimal process set points and recipes for process
.solar
ring6 Showing real-time trends of temperatures and units. Examples of some analytical and
pressures for laminators in module production. optimisation tasks are:
-pv-management.com
MES use for deviation handling ring6 Find correlations between wafer yield and wafer
Assume that the MES system gives a warning saws using tracking data. Differences in saw
during production, indicating that wafer yield has parameters are then used to find optimised
fallen below normal values based on automatic wafer sawing parameters.
data collection from the wafer line. When a process ring6 Optimize a cell printing line setup with regard to
engineer receives this warning, she wants to find cell efficiency by analysing cell efficiency
Issue II 2009
the root cause and device a solution to this correlated to printing line process data using
problem. She brings up the wafer yield report in single wafer tracking information.
the MES system, and drills into the data by to see ring6 Optimize energy use in a module laminator by
if the failed wafers may be traced to a specific analysing data to find optimised temperature
wafer saw, to a specific raw material batch or to and pressure profiles retaining quality and then Fig 3:
some other root cause. Another example would be build a model based controller in order to Status display in
to find the root cause of an equipment failure, such implement optimal set points and control. module production
as a wire breakage in a wafer saw. The procedure
could be:
ring6 Compare process parameters for the failure
run with OK runs.
ring6 Verify the wire batch to see if other runs from
same batch have problems.
ring6 Check alarm log to see if there are any specific
alarms
ring6 Check bricks to look for any indication of
inclusions
MES for process and product optimisation
When building a new plant, ramp-up speed is
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