Abstract
This paper presents the results of electrical performance measurements
of 204 crystalline silicon-wafer based photovoltaic modules following
long-term continuous outdoor exposure. The modules comprise a set
of 53 module types originating from 20 different producers, all of
which were originally characterized at the European Solar Test Installation
(ESTI), over the period 1982â1986. The modules represent diverse
generations of PV technologies, different encapsulation and substrate
materials. The modules electrical performance was determined according
to the standards IEC 60891 and the IEC 60904 series, electrical insulation
tests were performed according to the recent IEC 61215 edition 2.
Many manufacturers currently give a double power warranty for their
products, typically 90% of the initial maximum power after 10 years
and 80% of the original maximum power after 25 years. Applying the
same criteria (taking into account modules electrical performance
only and assuming 2 5% measurement uncertainty of a testing lab)
only 17 6% of modules failed (35 modules out of 204 tested). Remarkably
even if we consider the initial warranty period i.e. 10% of Pmax
after 10 years, more than 65 7% of modules exposed for 20 years exceed
this criteria. The definition of life time is a difficult task as
there does not yet appear to be a fixed catastrophic failure point
in module ageing but more of a gradual degradation. Therefore, if
a system continues to produce energy which satisfies the user need
it has not yet reached its end of life. If we consider this level
arbitrarily to be the 80% of initial power then all indications from
the measurements and observations made in this paper are that the
useful lifetime of solar modules is not limited to the commonly assumed
20 year.
Users
Please
log in to take part in the discussion (add own reviews or comments).