This brief presents the model-based negative-feedback-control (NFC) for maximum power point tracking (MPPT), with an improved $\text{V}- {f}$ model including the switch turn-on resistance in the switched-capacitor (SC) converter. The method is more efficient than the conventional simulation-based method to obtain the target ${V} _{\mathrm{ T}}- {f} _{\mathrm{ T}}$ curve of the solar energy harvesting system (EHS). Meanwhile, this brief compares two different MPPT schemes: maximum input PPT (MIPPT) and maximum output PPT (MOPPT). We find that MOPPT is more suitable for maximizing the utilization of solar energy. This design, implemented in 0.18 $\mu \text{m}$ CMOS and measured with a $4 {\times }4$ cm2 solar cell, exhibits an improved $\text{V}- {f}$ model with an average tracking error of 0.47% for the MOPPT. MOPPT transfers more power to the load circuits than MIPPT and achieves a peak efficiency of 90.3% at 3k lux.