Solar Battery Charging

Step 8 I want more voltage!

In order to double the voltage you need to join two solar panels in series. i.e. you need to connect the negative terminal of one solar panel to a positive terminal of the other solar panel. This will then leave you with a positive terminal from one panel and a negative terminal from the other to connect your wires to. In this case you would then have a solar panel rated at a maximum of 6V at 150ma ( the maximum voltage of a single panel is 3V ). More voltage would allow you to charge more batteries at one time - just remember that although 3V is the maximum rating of the solar panel you need to get an idea of the typical output for your climate. The batteries would also need to be connected in series ( negative to positive like in most multi-battery devices ). The circuit diagram shows below the solar cells in series and their accumulative voltage

Comments

[rcisneros]

Question. What happens if the solar cells aren't the same? Or one solar cell goes into shade before the other? So you could end up with a cell pumping out let's say 1v @ 20mA and the other 3v @ 100mA. Would they still just add up to a 4v output ? or You could have a cell pumping out let's say 1v @ 100mA and the other 3v @ 20mA. Would they still just add up to a 4v output?

[sumgupta89]

we know that solar panel gives maximum power at particular voltage.which is a bit less then the actual rating of the panel. my aim is to get a constant voltage across the battery,okh. but can i do sth by which i can get such const voltage 4 which the power provided by by solar cell is maximum. i can introduce a microcontroller which will continuously check the voltage ......and will get stuck at dt particular voltage...but i am getting puzzled with dat,ne idea plz

[NightLord]

So if I have 2 x 6V solar pannels joined in serries (=12V) and 3 x 4.2V batters wired in series, I can charge them right?

(I just want to make shure, because I don't want to damage the batteries since they here quite expensive)

Btw, cells reach their max voltage very fast, mine even exceded it at very strong day light. But it's different with current, in the morning I only got about 15% of max current output. On the other hand, overall power output was actualy 10% bigger in the evening.

[belcat]

There's no over-charge protection on this circuit --- it's not needed if the charging current is less than 10% of the capacity of the battery (which it should be with the parts mentionned). If you add more solar panels in parallel, you may need overcharge protection.