Clipping-corrected performance ratio: a new metric for high DC:AC ratio PV systems

Open Access

Table 1

Glossary of symbols used in this paper.

Symbol	Definition
P_out,k	System power output recorded at timepoint k
PR^′_25°C	Performance ratio corrected for STC
PR^′_25°C,bi	Bifacial performance ratio corrected for STC
PR^′_CC	Clipping corrected performance ratio
PR^′_CC,bi	Clipping corrected bifacial performance ratio
P₀	DC installed (rated) power capacity of the PV system. Equal to the sum of all module nameplate power ratings.
P_AC,0	AC maximum output power capacity of the PV system. Equal to the sum of all inverter AC power ratings.
τ_k	Duration of the k^th recording interval
G_POA,k	Plane of array irradiance recorded at timepoint k
$G_{P O A, k}^{r e a r}$	Rear-side plane of array irradiance recorded at timepoint k
G_ref	Reference irradiance at STC
G_CC,k	Clipping corrected irradiance at timepoint k
G_C,25°C	Clipping threshold irradiance
C_25°C,k	Temperature correction factor at timepoint k
T_mod,k	Module temperature recorded at timepoint k
T_amb,k	Ambient temperature recorded at timepoint k
γ	Power temperature coefficient of the PV module
φ	Bifaciality ratio of a bifacial PV module
T_{mod,annual-avg}	Annual average module temperature (depends on the location)
I_MPP	DC module / string current at maximum power point
P_MPP	DC module / string power at maximum power point
I_MPP,0	Module nameplate maximum power point current rated at STC
PR_true	True performance ratio. (The statistical expectation of the annual average performance ratio of a system in a given location assuming that the system condition does not change or degrade from its current state.)
PR_expected	Expected true performance ratio for a normally behaving array. The value of PR_expected is equal to PR_true of the default array for the same location.

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