The document discusses different types of warranties for photovoltaic (PV) modules. It explains that modules have both a materials warranty that covers defects, and a power warranty that guarantees the module will produce a certain percentage of its rated power output for a set time period. Common power warranties are 90% output for 10 years and 80% for 25 years. The document also discusses decreasing PV module prices over time, with retail prices reaching an all-time low of $2.65 per watt in September 2011. Quality and manufacturer reputation are important factors to consider despite lower prices.

1. 52 home power 146 • december 2011 & january 2012
PV 2012
Warranty
Every PV module carries two distinct types of warranty—a
materials (or workmanship) warranty and a power warranty.
The materials warranty covers the module’s parts and
workmanship. It is critical to read the fine print, but a
materials/workmanship guarantee generally provides service
or replacement of defective modules by the manufacturer.
Some of the limitations are based on the parts that module
manufacturers use to assemble modules, such as quick-
connects and sealed junction boxes, which have their own
warranties from their own manufacturers. Of the more
than 830 modules on the list, 500 carry at least a five-year
materials/workmanship warranty and about 250 are at 10
years.
A module’s power warranty guarantees that the module
will produce a certain percent of its rated STC power (Pmp,
minus any power tolerance) for a given period of time. A
common warranty is 90% of rated power for up to 10 years and
80% for up to 25 years. Silicon Energy and MAGE Solar offer
30-year, 80% rated-power warranties—tops on the list. (Silicon
Energy also offers a best-of-list 15-year, 90% rated-power
warranty.) All of the modules that have 10-year materials
warranties have at least 25-year, 80% rated-power warranties.
...and Cost!
Compare all the stats you want: the majority of consumer
decisions are made first and foremost on price, and module prices
have decreased for the last several years. Global fluctuations in
demand have and will likely continue to occur—entire nations
have implemented, adjusted, and/or repealed various incentives
for grid-connected PV systems. Furthermore, it takes time for
manufacturers to scale up to meet demand. Combine these two
factors, and the result is a market where supply can, and often
does, exceed demand.
Solarbuzz is a company that tracks PV industry price trends
(see www.solarbuzz.com). Their retail module price index shows
modules at an all-time low of $2.65 per W as of September 2011,
around half of what modules cost at the start of 2002. These are
retail prices, with distribution and installer markups included, and
do not take bulk pricing into consideration. Many modules are
available for less than $2 per W, with some below $1.50 per W.
Many utilities and states are reducing rebates for PV systems.
Fortunately, this corresponds with all-time-low module prices,
meaning system costs are decreasing ($ per installed watt) as
well. As in any market, prices will continue to fluctuate based on
supply, demand, and government support of the industry.
When thinking about purchasing cheap modules, realize that
you might get what you pay for. Quality matters, and often it
becomes a factor over time. Consider how long your module
manufacturer has been around. Reputation must be earned, and
word of mouth has impact.
Module prices aren’t part of this list because, like any commodity,
price isn’t fixed, but rather depends on who you know, how many
you buy, and what overall manufacturing price trends are.
Module Price Index
Silicon Energy’s power warranty is 15 years at 90% of rated
output, and 30 years at 80%.
Module prices aren’t part of this list because, like any
commodity, price isn’t fixed, but rather depends on
who you know, how many you buy, and what overall
manufacturing price trends are.
2003 2004 2005 2006 2007 2008 2009 2010 20112002
5.50
5.00
4.50
4.00
3.50
3.00
2.50
2.00
CostperWatt
United States ($) Europe (€)
Courtesy Silicon Energy
PercentofRatedWatts
Warranty Period (years)
70%
75%
80%
85%
90%
95%
100%
0 5 10 15 20 25 30
STC Rating (including tolerance)
80% for 25 yrs.
90% for 10 yrs.
80% for 25 yrs. Linear
(0.8% per year)
*Blue line is worst case for a stepped power warranty
Typical Power Warranties
Data Courtesy Solarbuzz