Climatological factors influence the performance of grid-connected photovoltaic systems (PV). These factors vary according to the altitude above sea level. The present work aimed to compare the performance of a PV with a string inverter (String PV) versus a PV with DC-DC power optimizers (DC DC PV) at 3800 meters above sea level (m.a.s.l.) under natural conditions. For this purpose, two PV of 3 kW each were installed, and their performance was measured under the IEC 62053 standard. Then multiparametric regression models were applied for each of them. The results were Validate through linearity, normality of the error terms, correlation, autocorrelation and homoscedasticity. Subsequently, the cross-validation of both models has performed, whose results showed that the DC-DC PV has a better result in 6.09% over the String PV model, so we conclude that the DC-DC Pv converter performs better at 3800 m.a.s.l.