| briefs from Intersolar North America 2011 the trade
Backsheet Blues | Except for the few PV
modules laminated between sheets of glass,
every panel has a plastic backsheet. Should you
care where that plastic sheet comes from?
John Jordan of Dunmore Corp. thinks you
should. First, it’s an important piece of the
weatherproofing system — its failure would be a
warranty failure. Second, it’s an important contributor to the manufactured cost of the module.
Not because the material is expensive (it’s not)
but because a properly designed backsheet-and-adhesive system can greatly reduce process time
and cost in the factory.
Dunmore has developed a “FastCert” pro-
gram to help module manufacturers get new
products through testing and certification quick-
ly, in nearly any country around the world. And
Jordan encourages module buyers to check the
Dunmore authenticity mark on the backs of new
modules to be sure they haven’t been shipped a
1,000-Volt Inverters, and Higher |
At the end of June, American Electric Technologies Inc. (AETI) introduced its UL-approved
1,000-volt inverter, the “integrated solar inversion station,” or ISIS. ISIS handles utility-scale
power up to 1 megawatt, at a claimed 99 percent efficiency. Until now, 600 volts has been
the customary limit on photovoltaic (PV)
strings in the United States, though 1,000-watt
systems are common in Europe. The advantage
of carrying a higher voltage is lower amperage
through the wires and better efficiency through
the transformers. AETI claims up to a 15 percent
improvement in wattage from the strings.
Look for competing 1,000-volt inverters
from AETI’s competition. And it’s just a start.
The next generation of utility- and commercial-scale inverters will handle voltages to 1,200 and
1,500. Some balance-of-system vendors (Cooper
Bussmann, for instance) are already in production with fuse holders and AC/DC disconnects
to handle 1,500 VDC.
Copyright © 2011 by the American Solar Energy Society Inc. All rights reserved.
Silver Shortage | The photovoltaic business now uses about 7 percent of all the silver
mined in the world today.
That startling fact comes from Andy London,
vice president of Heraeus Materials Technology,
which makes the silver paste used to screenprint
electrical conductors onto PV cells.
By comparison, 60 percent of silver production gets locked up by speculators, and held
in bank vaults. That means the solar industry
uses nearly 18 percent of usable silver. London
notes that because the price of silver has tripled
in 30 months, while the price of polysilicon
has dropped 70 percent in the same period, silver paste now accounts for up to 10 percent of
the cell cost (the silicon wafer is 25 percent).
You can’t skimp on silver, either: Printing a
thinner layer, or mixing it with a base metal,
reduces conductivity and cell output, just when
module manufacturers are working hard to
Heraeus, founded in 1968, uses 3 million
ounces of silver a month. At $36 per ounce,
that’s $108 million. If the worldwide PV industry continues to grow at 30 percent annually, in five years we’ll be bidding for half the
non-investment silver in the world. Buy it while