I have two 5v solar cells in series (10v in total) that are connected to a battery charger IC. The charger has a max forward voltage of 5v. The reason for using two solar cells is so that in lower light environment the battery can still charge.
I want to avoid burning the IC burning in cases where the solar cells are in fully exposed to light (so producing 10Volts). I can't use linear voltage regulators or buck converter because it significantly decrease the solar panel efficiency when the voltage is bellow the max threshold of 5Volts.
I've tried some circuits using zener diode and transistors to deactivate on the solar panel when voltage is too high but without success.
Could anyone provide a possible approach to achieve that results?
TLDR: I have a solar cell that produce 10 volts and a battery that charges at 5 volts. How can I limit the solar cell output voltage to 5v without deteriorating that voltage when it falls below 5 volts