Reviving lawn light solar cells.
I have several solar cells from old dead lawn/driveway lights. Ultimately, I'm sure that it was the rechargeable battery that failed, but the solar cells are in some sorry shape, also.
While they have not been tested outside in bright sunlight, in my workshop, shining a high lumen flashlight (unsure of exact output, but it does reflect significant heat to the lighted area) produced less than 600mV. The rechargeable battery is AA size (1.5 V).
The cell faces have heavy oxidation, which is going to block light, I know. The cell faces are encased in some sort of clear epoxy/resin substance. The connections are badly corroded, rust is evident around cell connections (which I found strange, but perhaps it dripped down from housing screws). I know that the connections can be replaced somewhat easily, but what about the oxidation? Without knowing what material is is encased in, how should I proceed in removing oxidation?
No flashlight can compare to the sun, I know this. But even without a true solar test, I know that these cells will not experience optimal performance.
What can be done to revive these cells?
Thank you in advance for any suggestions!! You all help me learn!