Hello everyone,
May you see this document, It uses dead batteries to capture the Radiant energy and improve the charging capabilities of the secondary battery, the document is pretty reasonable.
So if the dead battery cannot come alive, at least it can convert radiant energy for rest of the batteries. I agree with the fact that all of the radiant energy is not properly captured in these circuits. This can be verified by using different size capacitors instead of batteries. By calculating 0.5*C*V^2 for them, you may find out that running the SSG for a certain amount of time will accumulate different amount of energy.
I had found this article some time ago on one of the forums I don't remember.
Happy charging
Elias