Inverter - Function of Power

Function of Power inverters use a function of normalized power to calculate the efficiency of conversion from DC to AC.

General

Name

The name of the inverter entered here must also be unique across all other inverters in the model.

Category

Select the type of inverter from the options below:

 

Availability schedule

The schedule that describes when the inverter is available. If the inverter is scheduled to not be available, by scheduling a value of 0, then it cannot produce AC power and will not consume ancillary power during standby. Any non-zero schedule value means the inverter is available to produce AC power and consume ancillary power during standby. If the Inverter is scheduled to be unavailable but it is being supplied with DC power anyway, then the energy is dissipated as heat.

Function of Power

Efficiency function of power curve

This is the curve representing the relationship between DC power input into the inverter and the efficiency with which that power is converted to AC. The curve can be of type Linear, Quadratic, or Cubic. The curve’s “x” value is DC power input normalized by the Maximum continuous input power (below). The result of the curve should be power conversion efficiency expressed as a fraction between 0.0 and 1.0.

Rated maximum continuous input power

This field contains the rated power input (in W). This is value used to normalize input power for use with the curve named in the previous field. This is DC power from the PV arrays going into the inverter.

Minimum efficiency

This field contains a minimum bound on the inverter efficiency. This value will be used as a limit on the curve’s result.

Maximum efficiency

This field contains a maximum bound on the inverter efficiency. This value will be used as a

limit on the curve’s result.

Minimum power output

This field contains a lower limit on the AC power produced by the inverter (in W). If the resulting power output would be below this level, then the inverter is assumed to not produce any power and is in stand by mode. All DC power input is lost (unless it is going into storage).

Maximum power

This field contains an upper limit on the AC power produced by the inverter (in W). If the resulting power output would be above this level, then the power produced is capped at this level with the rest of input power converted to losses (unless it is going into storage).

Ancillary power consumed In standby

This field contains the ancillary power (in W) used by the inverter when not producing AC power. This is AC electricity consumed in standby mode. Standby mode occurs when the inverter is scheduled to be available but the incoming DC power is too low.

Heat Gains to Zone

Attach to a zone

If the inverter’s losses are to be modelled as heat gains to a zone in the building thermal model then check this option. Otherwise inverter losses are considered to be lost to outside.

Zone

When including inverter losses and heat gains to a zone select the building zone where the inverter is located.

Radiative fraction

This field contains the fraction of inverter thermal losses that enter the zone as long-wave thermal radiation. This should be a factor between 0.0 and 1.0. The balance of the losses is convective. This data is only required when including inverter losses and gains to a zone.