This paper presents a noise analysis of an optical receiver that uses a solar cell as a photo-detector to enable simultaneous energy harvesting and data reception. The noise analysis considers intrinsic noise generated by the electronic components of the receiver and includes the operation of a switching DC-DC converter, which is needed to draw the maximum amount of energy from the solar cell and transfer it to a load. The analysis yielded a noise model that is shown to be in good agreement with experimental measurements and was useful in identifying dominant noise sources, which in our case was a biasing circuit.