Interconnect target (storage.interconnect_limit_kw)

What it is

The power at the grid connection the battery works against, in kilowatts. With AC coupling the battery charges from production above it and discharges to bring the injection up to it. The target is soft: injection the battery does not take, because it is full, at its charge power or not charging in that hour, passes through and is reported as e_above_target_kwh. With DC coupling the battery never charges against it: under every dispatch it caps the inverters' combined AC output, before the AC losses, in the hours the battery discharges, so the grid injection then stays below it by the AC losses.

Typical values and how to get it

The export limit of the interconnection agreement. It is required for AC-coupled clip capture and daily full cycle. AC-coupled timed discharge does not use it for its dispatch. The right-size rule sets it to 0.8 times the system AC nameplate. With DC coupling, enter the export limit when the interconnection holds the system below its AC nameplate, or leave it empty for the system AC nameplate, where the inverters' own ceiling binds first; the right-size value caps each discharge hour's inverter output at 0.8 times the nameplate. A hard limit is the grid power limitation of the AC losses (ac_losses.grid_poi_limit_kw). An AC-coupled battery charges from the system's final output, so for a clip-capture study leave that limit at 0 (no limit) and let the target cap the injection. With the grid power limitation switched off on the Model tab (ac_losses.use_grid_limit false), the battery has no hard limit.

How it is applied

c_i = \min\!\left(p_i - P_{tgt},\ H_i,\ \frac{P_{bat}}{\eta_c}\right) \quad \text{when } p_i > P_{tgt}

where

Symbol	Meaning	Unit
$c_i$	the AC power taken to charge at timestep $i$ under AC-coupled clip capture	kW
$p_i$	the system's grid injection before the battery at timestep $i$	kW
$P_{tgt}$	this target	kW
$H_i$	the charge power that fills the battery within timestep $i$ : the room left below the state-of-charge ceiling divided by $\eta_c\,\Delta t$	kW
$\Delta t$	the length of one timestep	h
$P_{bat}$	the power rating	kW
$\eta_c$	the charge efficiency	—

References

Denholm, Eichman & Margolis 2017, "Evaluating the Technical and Economic Performance of PV Plus Storage Power Plants", NREL/TP-6A20-68737

API

storage.interconnect_limit_kw

Symbols follow the symbol registry.