Plant battery voltage reversal???

Not entirely sure whats going on here but after setting up the plant battery with a polarized capacitor and double and triple checking the connections, it seems that the battery has suffered a voltage reversal?. Not sure exactly what that means or how to tackle it, but I think it could be because of a lack of load and also the moss drying out for a period. I guess I will try again from scratch and see if we can get it working with the correct polarity which will hopefully also show a greater output…