make a solar panel

[mossrisjhons]

Hello,
I am hoping that you would be kind enough to help me with a question. I would like to use 4 LED's for a solar powered lamp that I am building. Would you be able to tell me exactly what kind of rechargeable batteries I would need for the 4 LEDs and if I need resistors? Is it necessary to have a pcb board for this project? And finally, maybe it's a longshot but does anyone know if there was a kit available for an outdoor solar lamp? Using the solar path lights just wouldn't provide enough light in the lamp.
Thanks in advance.

[mrpackethead]

hi mossris.. Theres a lot of variables in there! Lets start with what kind of Leds you want to use.. From there we can establish what kind of batterys you will need, and almost certainly you won't want to use reistors to limit the current. Under solar conditions every bit of energy is valuable so, you'll almost certainly want to consider some kind of high efficeny regulator.. I'm sure that there are kit sets.. Google is your freind.

[BuzzKill]

Ya .. lot of variables.

Its all just math though.

How many milliamps do the LED's draw?
How many milliamps does the solar cell produce in full sun?
How many Amp/Hours do your batteries hold?
How long do you want the light run?

You have to reach a balance between how many amp/hours the LED's will draw from the batteries for the duration of your expected run time, against how many amp/hours can your solar panel put back into the batteries during the next day.

Rechargeables come in many flavors. A kit I just bought from Costco has AA NiMh with 2000mA/h batteries (2 amp hours).

Some basic quick math sez....

You can run 6 - 30ma LED's off 3 rechargable AA 2000mAh batteries wired to make 4.5 volts for about 10 hours or so. Which just happens to be in line with what a backyard solar light seems to run, or there abouts.