Victory!
So I finally decided that all my previous testing was invalid. I did not have the 3310 with me and the chargers were all designed for 230V AC in. Except for one car charger that was not designed for Nokias. I corrected that todayat the expense of 13 euro. After a brief test in my car, I cracked the charger and found very little room for adding components or connectors.
But then I noticed I had a female connector I could fit in the "nose" if I would remove the shiny pin. Now it connects to one of the many convertor cables that come with the solar panel.
Here is the proof. It works! No need for bright direct sun light. Overcast is fine. Behind a window is fine. Batterij wordt opgeladen! Even if the solar panel outputs about 7-8 Volts, it will start working. Once busy charging you can even take the panel indoors and the charging will continue even if the produced voltage drops under 7 V. I reckon the Nokia charger halts at 6 or 5 V.
Whoopee. Or not? I consider this not a neat hack, but cheating. I don't really care about that. It comes with working to deadlines. Deadlines kill creativity. So stop hurrying me on those legs dammit!!!