I am glad to read that the sun arrived. I went last christmas there and we miss the daystar.
Anyway, I have been testing a couple of kits attached to solar panels for the last weeks here in Barcelona and the sun was enough powerful to maintain the kits alive from one day to the other (and these panels were not being hit for more than 2 or 3 hours!).
It is true that two cloudy days in a row with clouds (or with not sun at all), caused the shutdown of the kits but if your battery reaches the 100% after the solar panel being hit by the sun during the day, it should be enough charge to keep your device alive (at least) until the next day.
Can you send me your kit’s URL so I can check out the graphics!?
I would not ditch the the solar cell & battery yet. Using a larger battery could be a solution. Also changing the connection and posting intervals of your kit, but if you want to still connecting and sending data every minute this is not a good option.
In any case, try to expose your solar panel as much time as possible to the sun and check out the values of the solar panel/battery during the day.
I look forward to hearing from you.
All the best.