This paper presents results on variability of outturn
shortfalls about the expected value indices which are usually
presented in resource adequacy studies, for a range of Loss of
Load Expectation (LOLE) levels and installed wind capacities
in a test system generally representative of future Great Britain
system scenarios. While the details of results will clearly vary
between systems, one very general conclusion is possible. In the
results presented, for a given LOLE level, the probability of very
severe out-turn in a future peak season is much greater at high
installed wind capacity. Thus for this system, as the installed
wind capacity increases, a constant level of LOLE cannot be
taken as an indicator of an unchanging overall risk profile of
the system. This further demonstrates that in any system, LOLE
cannot be assumed to be a good summary statistic of risk profile
as the installed variable generation (VG) capacity increases, and
that it might be necessary to reconsider the near-universal use of
expected value risk indices as the main headline indices in utility
adequacy studies.