In this Part 1 article of this series of articles, a new methodology to refine the Co-Content function \(\left(CC\left(V,I\right)\right)\) is proposed, consisting on fitting the current minus the short-circuit current \((I-{I}_{sc})\), to an \(N-1\) order polynomial, where \({N}_{points}=N\), is the number of measured current-voltage \(\left(IV\right)\) points, and integrating it to calculate \(CC\left(V,I\right)\). The shunt resistance \(\left({R}_{sh}\right)\), the series resistance \(\left({R}_{s}\right)\), the ideality factor \(\left(n\right)\), the light current \(\left({I}_{lig}\right)\), and the saturation current \(\left({I}_{sat}\right)\), are then deduced, in the case of a constant percentage noise or a percentage noise of the maximum current \(\left({I}_{max}\right)\). In the former case, \({R}_{s}\), \({R}_{sh}, n, \text{a}\text{n}\text{d} {I}_{lig},\) can be deduced with less than 10% error, using only \({P}_{V}=\)51 \(\frac{number of points}{V}\), even if the noise is as large as \({p}_{n}=0.1 \text{\%}\), with a computation time around 80 ms. \({I}_{sat}\) needs \({p}_{n}=0.05 \text{\%}\) or less, and \({P}_{V}\) equal or larger than 501 \(\frac{number of points}{V}\). For the latter case, \({R}_{s}\), \(\text{a}\text{n}\text{d} {I}_{lig},\) can be obtained with less than 10% error, using only \({P}_{V}=\)251 \(\frac{number of points}{V}\), and \({p}_{n}=0.1 \text{\%}\), or smaller, with total computation time around 49 s. \({R}_{sh}, {I}_{sat}, \text{a}\text{n}\text{d} n\) needs that \({p}_{n}\le 0.05 \text{\%}\), and \({P}_{V}=\) 751 \(\frac{number of points}{V}\) or larger. A computation time expression of the form \(time=E{{N}_{points}}^{m}\), is deduced. The methodology proposed in this article is appliable to unevenly/randomly distributed *IV* data points, and it is implemented in Part 2 in solar cells’ and photovoltaic modules’ experimental \(IV\) reported in the literature, to deduce their five solar cell parameters.