Hybrid Energy Systems : The Demand Side

Nomenclature Symbol/Abbreviation Unit Definition Cb kWh Battery capacity Cpv kW PV capacity D h Peak load duration; hours per day that the load is greater than 90% of the daily peak load Ea kWh Annual energy purchased from a utility not factoring in any excess PV energy sold back through a net metering agreement E90 kWh Area under a load duration curve above the 90 %ile of the original load E90,avoid kWh E90 avoided; the difference between E90 of an original and modified load GPL kW Grid power limit; measured in terms of a percentile on a monthly net PV load duration curve Nh --Number of houses in a microgrid; Nh=1 for a single house P kW Electrical load at time t Pp kW Annual peak load; maximum point on a load duration curve Pp,red kW or % Reduction in PP Ppv kW PV power at time t Ps kW Battery power at time t; positive = charging, negative = discharging P90 kW 90 th percentile on a load duration curve; the level of power the load is below 90% of the year P90,red kW or % Reduction in P90 Qb kWh Battery charge at time t RCb, RDb, RCC, RDC, RCS, RDS kW Maximum charging (RC) and discharging (RD) rates for the battery (b), controller (c), and entire storage system (s) ηb % Roundtrip battery storage efficiency