Precision manufacturing is key to producing weather-resistant solar panels. Integrated motion and control systems from Siemens provide the needed accuracy and performance.
A market growing at 45 percent per year looks like a good bet to get
into. According to Mike Taylor, director of research and education,
Solar Electric Power Association, the solar photovoltaic for electric
generation market has been on that slope for the past three years. No
wonder automation companies are developing solutions for the solar
Taylor says that Europe has been the photovoltaic
leader, but that the U.S. market is rapidly developing. Putting to rest
the myth that solar implementations require never-ending sun, the
current market leader is Germany–not exactly a sunny country. Spain
follows, with the United States third in market size.
United States, we just broke the 300 megawatt (MW) barrier in
photovoltaic electric generation in 2008. By comparison, in 2007 the
total was 160 MW and in 2006 it was not quite 100 MW,” says Taylor.
“With the entry of utilities and big box commercial stores into the
(solar energy use) market, it’s just going to keep growing.”
has been involved in the solar industry for many years and has honed
its automation offering to fit the needs of solar panel manufacturers.
Apparently simple from the outside, these panels are multiple layers of
materials that must be precisely sized, cut, stacked and sealed. If
dirt, dust or contaminants land on any of these layers before the unit
is laminated, it more than likely will affect the performance of the
solar panel. The assembly process must assure the final product is
impervious to weather and other outdoor environmental hazards.
manufacturing process includes accurately measuring, cutting,
transporting, positioning and stacking insulation, protective film and
other layers of proprietary films onto expensive and fragile sheets of
photovoltaic silicone without contaminating any of the layers. If the
silicone layer is dropped, bumped or hit with too much force, the
sheets can crack or break into shards. The films come from rolls and
are cut to length and registered to position onto the substrate. The
end result is a hermetically sealed panel that converts solar energy
into electricity for residential or commercial use.
A company located near Chicago specializes in building machinery to manufacture these panels. A Siemens 317T programmable logic controller
“This was a new project for this customer,” says Ken Brey, technical director for DMC Inc.,
an automation engineering and software services company located in
Chicago. “This customer requested Siemens equipment to match the rest
of their automation equipment. They know that Siemens equipment would
not only give them continuity in the hardware and software, but would
also give them the high level of performance and operation they
expected. They also know from experience that Siemens service is much
easier to get globally than other brands.”
(PLC) controls the process. This PLC employs CPU 317T-2 DP technology
which adds powerful motion control functions to the existing range of
standard central processing units (CPUs). These motion control
functions are integrated in the CPU firmware and are supported by a
co-processor for high-speed closed-loop control. This ensures that the
performance of the CPU 317 for normal control tasks is maintained and
that the motion control functions can be computed at a higher clock
Like making a sandwich
Brey explains it, the process of making these panels is similar to
making a sandwich. Instead of bread, glass panels make up the first
layer. Instead of meat or cheese, EVA and insulation material make up
the second layer. The solar panels get placed into the sandwich and are
put into a laminator to seal everything together.
customer’s machines cut and place the middle layers onto a vacuum
conveyor. The machine positions the panel under the leading edge of the
EVA and feeds the panel and the EVA together to build our “sandwich.”
The laminating process is done with another company’s equipment,”
states Brey. “The end customer was building an entire factory from
scratch with equipment from different vendors. Standardizing on
Siemens was the quickest and easiest way for the equipment to
communicate as well as ensuring the job met the customer's high
expectations,” according to Brey.
A typical motion control
application like this assembly process needs to control 2 to 8 axes.
The Siemens 317T PLC can control up to 16 axes. In addition to accurate
single axis positioning, the technology CPU is particularly suited for
complex, synchronized motion sequences, such as coupling with a virtual
or real master, geared synchronous motion, electronic cam discs and
print mark correction. Print mark registration is particularly
important in the solar panel lamination process so film is properly
aligned onto the photovoltaic cells. Using Siemens STEP 7 software, only one program is needed for PLC and motion control, making configuration and programming significantly easier and faster.
processor in the solar panel assembly machine has motion control
functions integrated into the CPU that guide four servo axes to
position the film. It allows the process to run at high speeds without
a separate motion controller. Accurate registration of the film is
achieved using the built-in geared synchronous motion and measuring
probe functions of the 317T PLC. Siemens solution provider, DMC, Inc.,
installed the control system at the manufacturer’s facility near
Chicago and the machine now resides in the photovoltaic panel plant in
SEPA’s Taylor has calculated from public announcements
of utilities that 2,500 MW of electric generation from photovoltaic
panels is projected for manufacture in the next five years. With
utilities and large commercial enterprises such as Wal-Mart looking at
adding solar generating equipment, the demand for these Siemens
controlled assembly machines should be sky high.
For more information on Siemens Solar Industry Solutions, please click here.
Filed Under: Factory automation, Green engineering, Motion control • motor controls