Battery Charging Using Solar Power

Even then it still wouldn't work SABorn, the NiMH will still continue to receive some current, NiMH's can not be constantly charged once full it damages their chemistry over the long term, aside from a peak voltage limit you'd have to prevent the cell from being charged at all once it was full. You could use NiCad's they do tolerate trickle charging for longer period of time.

Ok. I did a little math, since I live in a tropical country there is no winter. In how days the sun is up for about 9hrs. I estimated the time when does users normally need their devices to be charged so 8am-11pm is the time where the station will be at use (9hrs. of sunlight for about 8am-5pm). I'm wondering, if the sun is present during the usage of the station, should the battery kept charged always or only when the rating drops to 50% then it charges the battery? If like that, I think the 20w 12v panel is enough to charge back the battery for 5hrs. Is my logic correct?

How about using a PIC and relay to control the charging?

If the sun is truly present during charging you'll need a far smaller battery, you need to quantify when the device will be used outside of a sun light situation to determine the battery size. You still absolutely need to define EXACTLY what type and the number of devices you wish to charge, and the other power draws on the system. If you can't post that power availability question then you've been wasting our time for the last week!

These are the exact devices that will be charged: cellphones (specifically brands like nokia, sony erricson, lg, samsung, and others), mp3 players (specifically ipods, phillips, samsung and others). The other power draws I consider are the PIC's, 4 lcd and 4 keypads, the coin slot/s, the motor used to control the tracker.
The number of devices that will be used is 4. 1 in each compartment, so a total of 4 compartments.

I hope that is enough for you guys to help me in this project of mine.

You need to work out how many amps each device draws for charging over what period of time.

Just quoting the device, dont tell us a darn thing to work with. Do you expect one of us to go and test each one of these devices to give you the results you ask for.

If device X draws 0.5 amp and takes 2 hours to charge then we have data to work with, without actual data then is just guessing.

So you understand, can you tell me how much power my lounge room light uses?
Without details i doubt if you can answer the question, its the same with what you are asking.

Pete.

ok ok. Please don't get mad, I ain't a know how so bare with me, that's why i'm asking for help.

Will this be a start? I have a cellphone battery with a 950mAh 3.6Wh 3.7v. How do I solve to know how many hours it will get full charged?

You really got a lot to learn, you should try researching this yourself via Google, there is PLENTY of information on batteries out there and it behooves you to find it before every user here as to repeat what already exists elsewhere. It's pretty self explanatory how long that size battery will take to charge if you realize that mAh means miliamp HOURS. Charge rates are very seldom at the full capacity of the cell (IE you wouldn't generally charge a 950ma battery with 950ma of current) you'd use something like 1/4C which would be 950ma / 4 = 237ma, and since it's only being charged at 1/4C it would take 4 hours to charge at 237ma. That's very rough math for approximate capacities and will only allow you to ballpark your needs.