Will a solar charger damage my phone battery?

No. Modern phones regulate incoming power regardless of source. Solar panel voltage fluctuations are handled by the phone's charge controller. Your phone doesn't know or care that the power is solar.

Can I solar charge through a window?

Glass blocks 30-50% of solar energy. A 20W panel behind a window may only produce 10-14W. It works but is much less efficient than direct outdoor sun exposure.

Best Solar Chargers for Phones 2026