# Converting Annex42 power curve to Normalized power curve for fuel cell CHP

I have a fuel cell as part of a model and I'd like to scale it up to better match the heat demand of the dwelling.

The only source I have for the parameters of a power curve are those in the Microcogeneration.idf example file, shown below. This curve is used in the `Generator:FuelCell:PowerModule`

object, and is used in `Efficiency Curve Mode`

, `Annex42`

. This indicates that it's not normalised (unlike with other power curves in EnergyPlus). The documentation suggests that when a study is looking at changing the power output of the fuel cell then we should use
mode `Normalized`

.

My question then is what do I need to do to this `Curve:Quadratic`

object to make it into a `Normalized`

curve?

```
Curve:Quadratic,
FCT Power Curve, !- Name
0.642388, !- Coefficient1 Constant
-1.619E-4, !- Coefficient2 x
2.26007E-8, !- Coefficient3 x**2
0.0, !- Minimum Value of x
10000; !- Maximum Value of x
```

From the documentation:

**Field: Efficiency Curve Name**

*This field contains the name of a Curve:Quadratic input object described elsewhere in the input file. The curve is a function of the net DC electric power, (W), produced by the power module and describes either the electrical efficiency or the how the efficiency is modified depending on the mode selected in the previous field. This quadratic curve is just one part of the entire parametric relation used to describe electrical efficiency . For the Annex42 mode the full relation for efficiency is,*

*where the Curve:Quadratic input object named in this field serves to define the quadratic portion in the first set of brackets. For the Normalized mode the full relation for efficiency is,*

*where is the nominal electrical efficiency at the rating point which are described in the next two fields. The Normalized mode may be more useful for a simulation study that needs to vary the capacity of the FC.*

The nominal values given in the Microgeneration.idf are: nominal power (*Pnom*) = 3400 Watts, and nominal efficiency (*enom*) = 0.353.