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Solar Panel

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New Member
I bought a solar panel 5.5V/30mA,
i measured voltage in sunlight on the back of the panel, 5.6V:)
good to start .. to play with i soldered wires from the pads on the back of solar panel and brought them to a small pcb where i have a 0.1nF and 10uF cap .. and
stangely i get no voltage across the cap .. though i still get the voltage oin the back plate ..
tried using a diode in series before the cap - still same ..
tried removing the pcb - yet no voltage at the end of the wire !!!
do i need some load or some other circuitry .. or is there something wrong with my measurement :(


Well-Known Member
Most Helpful Member
You must have a broken connection.

If you are getting 5.6 V in one place and 0V in another place, they cannot be connected together.

If you short circuit the solar panel, there will only be a small current flow, so there will be no voltage, but the voltage will come back up to the 5.6V as soon as the short circuit is removed.


New Member
no it is not a broken connection - i did check the continuity of the wires ..
it was really difficult for me to believe too ..
5.6 volt on one end of the wire and 0 volts (-0.2 to be precise) on the other end ..
yes but thats what i saw ..
and now i see the possible reason .. maybe because i was using very thin wire and long ones (about 60 cm long)
the solar panel is not able to provide enough current or maybe all the voltage is dropping along the wire ..
ok - i did find a way out too .. i placed 100 uF cap behind the pcb of the solar panel ..
now it allows me to drive a led 60 cm away and still using a thin wire
maybe multiple repeating stages will provide better decoupling ..
just playing around with it .. shall let you know as i proceed
want to see what can be done without any complex circuit :)


New Member
the next step -
i used thicker wires and 10uF electrolytic capacitors on both sides of the wire
now i get a clean 5.6 vots on the other end of a 100 cm long wire and am also allowed to glow an led 50 cms further away using another thin wire tooo ..
now the problem is that i can barely mange to have an led light .. maybe i get about 10 mA or so ...
i want to drive a small relay say about 60mA of current so that i can use the relay outputs as a general purpose ones to drive motor or lights or anything else
will i need some inductor in series to increase current ..
would be nice if this could be done only using inductor, capacitor, and diode ..etc (a transistor or mosfet too doesnt sound to be too complicated)


New Member
yes - this is one of the small play panels ..
i have a palm sized panel rated 5.5V/30mA
and i get abut 5.8 Volts but only 10 mA current
would like to boost the current ..
so it would be nice to have say 4 Volts at 60 mA
any way this can be done ?


Well-Known Member
Nope, twice the current = half the voltage. You need a larger solar cell.

Solar cells are rated under "ideal" conditions, in reality it's much lower.
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New Member
can i use say 3 or 4 panels in parallel to increase current ..
does the rule to add up current hold true for solar panels too ?


Yes, but to a point higher voltage is preferred. The I^2R heating situation is better with a higher voltage rather than current, less loss in general.
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