Parasitics

The parameters on the Parasitics page describe parasitic electrical loads and other losses in the power tower system.

Page numbers relevant to this section from the Wagner (2008) and Kistler B (1986) references are:

•	Kistler 224

The parasitic loss variables are factors that Solar Advisor uses to calculate the estimated total parasitic loss and hourly parasitic losses, which are described in more detail below.

Solar Advisor calculates two types parasitic loss values. The first is an estimate of the total parasitic losses used to calculate the power block design thermal input, and the second are the hourly values calculated during simulation of the system's performance.

Note. Parasitic losses from components that do not exist in the system should be set to zero.

Input Variable Reference

Parasitic Energy Consumption

Variable	Description	Units
Startup Energy of a Single Heliostat	The electric energy in kilowatt-hours required to move each heliostat into position. Applies during hours when the heliostat is starting up.	kWe-hr
Tracking Power for a Single Heliostat	The electric power in kilowatts required by the tracking mechanism of each heliostat in the field during hours of operation.	kWe
Receiver HTF Pump Efficiency	The electro-mechanical efficiency of the receiver heat transfer fluid pump.	--
Storage Pump Power	The ratio of the electric power in kilowatts required by the storage pumps to the thermal power passing through the storage system.	MWe/MWt
Balance of Plant Power	Losses as a fraction of the power block nameplate capacity that apply in hours when the power block operates.	MWe/MWe
Cooling Tower Parasitic Power	The cooling tower parasitic losses as a fraction of power block nameplate capacity are electrical losses that occur when the power block operates at part or full load.	MWe/MWe
Piping Loss Coefficient	Thermal loss per meter of piping. Includes piping throughout the system.	Wt/m
Total Piping Length	Length of piping throughout the system: From the receiver to power block, power block to process heat, etc. The piping loss varies with output produced by turbine.	m

Estimated Total Parasitic Losses

The estimated total parasitic losses value used to calculate the power block design thermal input displayed on the Power Cycle page is based on the estimated total parasitic loss factor, which depends following variables and values:

The estimated total parasitic loss factor total_par in MWe of losses per MWe of power block nameplate capacity is given by:

total_par = stor_pump_par × stor_hours × 0.20 + 0.03 + bop_par + cool_par

Where,

•	stor_pump_par = Storage Pump Parasitic Power

•	stor_hours = Full Load Thermal Storage Hours (Thermal Storage page)

•	0.20 = estimate of the solar multiple where each solar multiple is assumed to require 5 hours of storage

•	0.03 = estimate of the tower pump parasitic loss fraction

•	bop_par = Balance of Plant Parasitic Power

•	cool_par = Cooling Tower Parasitic Power

The total estimated parasitic losses in MWe is then:

total parasitic loss estimate = total_par × Nameplate Capacity

Where Nameplate Capacity is the power cycle electric capacity from the Power Cycle page.

Hourly Parasitic Losses

Solar Advisor reports the hourly parasitic losses described in the tables below in the hourly results.

Table 28. Parasitic loss variable names used in hourly performance data.

Parasitic Loss Variable	Description
Par_store_pump	Storage pump parasitic losses
Par_plant_bal	Balance of plant parasitic losses
Par_cooling_tower	Cooling tower pumping parasitic losses
Par_pipe_loss	Piping thermal losses
Par_tank_htr	Storage tank heater electric parasitic losses
Par_recirc_htr	Recirculation pump parasitic losses
Par_total	Total parasitic losses
Hel_track_power	Electricity for heliostat tracking

The parasitic loss variables are calculated from the parasitic loss factors on the Parasitics page and variables from the hourly simulation.

Table 29. Equations used to calculate parasitic loss quantities in the hourly performance data.

Variable	Calculation
Par_store_pump	storage pump power × (flow rate from storage ÷ reference flow rate) × (Nameplate Electric Capacity ÷ Rated Cycle Conversion Efficiency)
Par_plant_bal	Balance of Plant Parasitic Power × Cycle_power
Par_cooling_tower	Cooling Tower Parasitic Power × Cycle_power
Par_pipe_loss	Piping Loss Coefficient × Total Piping Length × Cycle_eff × Cycle_power ÷ Rated Cycle Conversion Efficiency
Par_tank_htr	cold tank pump power + hot tank pump power
Par_recirc_htr	required recirculation energy ÷ Recirculation Heater Efficiency

The total parasitic load Par_total is the sum of the following parasitic losses:

•	Storage pump

•	Balance of plant

•	Cooling tower

•	Tower pump

•	Heliostat tracking

•	Piping loses

•	Storage tank heaters

•	Tower parasitic losses