In this Part 1 of this series of articles, the accuracy on the obtention of the shunt resistance (R sh), the series resistance (R s), the ideality factor (n), the light current (I lig), and the saturation current (I sat), via the use of the Co-content function CCV,I= ∫ 0VI-IscdV (where Isc=IV=0 ) is investigated theoretically, as function of the number of measured points per voltage ( PV ) and percentage noise ( pn ). Reasonable values are obtained for R sh, R s, and I lig, with PV = 11 measurement points per V if the pn is 0.1% or less. For a reasonable determination of n at least PV = 101 measurement points per V are needed. I sat determination requires pn of 0.01% or lower with at least PV = 101 measured points per V and should be evaluated at large values of V. The results given in this Part 1 are used in Part 2 to discuss the reported application of the CCV,I to obtain R sh, R s, n, I lig, and I sat found in the literature.