  This paper describes the energy resolution of Microwave Kinetic Inductance
Detectors (MKIDs), and models some limiting factors to it. Energy resolution is
a measure of the smallest possible difference in energy of the impinging
photons, Delta E, that the detector can identify and is of critical importance
for many applications. Limits to the energy resolution cause by the Fano
effect, amplifier noise, current inhomogeneities, and readout sampling
frequency are taken into consideration for this model. This paper describes an
approach to combine all of these limitations and predict a wavelength
dependency of the upper limit to the resolving power.
