Wireless microsensors can sense and share data that can save lives, energy, and money. Recharging or replacing thousands of tiny, easily exhaustible batteries, however, is too costly. Fortunately, photovoltaic (PV) cells can generate 100x more power from sunlight than other transducers can from motion, heat, or radiation. But since PV cells cannot supply the milliwatts that microsystems can at times require, this paper shows how to design battery-assisted PV-sourced CMOS charger-supplies that supply PV power to the system, excess PV power to the battery, and battery power to the system when PV power is insufficient. The design process proposed accounts for power losses and silicon area. This way, simulations show that 10% of losses are from switches when inductor resistance Resr is 2.2 Ω and silicon area can be 80% smaller when Resr is 5.5 Ω.