This is simple 1.2V AA battery Solar charger circuit. If you want to charge only one 1.5V AA battery and must used at outdoor that don’t has home electricity. We will also use fast it so we need to application devices near us.
This projects is very easy and cheapest because we use a solar cell 3V 160mA and I measure voltage about 3.3V as Figure 1 so enough for charging.
And I will use AA 1.2V 700mAh Rechargeable Nickel metal Hydride Battery.
In addition, we need to have a diode. To prevent reverse voltage from a battery to the solar cell when no sunlight.