Hey guys not a lot of specifics in this thread. I've spent a fair bit of time monitoring the charging profile of the N900 and it's got a fairly sophistocated charging system to check for current capability and voltage stability.

A solar panel is a constant current source. To simplify this as much as possible the voltage collapses when presented with a load. Using a voltage regulator will not help this either unless it is specifically designed with a solar panel and a regulated output in mind. Long story short, don't bother..

Charging profile (from memory, but measured and confirmed in the past) looks at the voltage stability and current in the first second or so. If this is not good the current used is locked off at ~90mA. Looks like it is charging but it's not a useful charge in reality. In the first few seconds the charge then is locked off at 500mA for a number of seconds, then following again the same for 600mA then 700mA. This is an approx. look at the charging profile as a charger with the centre pins shorted..