Hello fellow electronic enthusiasts.
I am having a problem with a voltage drop on PV input on my Sunny Buddy.
Before I connect PV cells, output voltage from PV cells are 12.67V.
When I connect PV cells on Sunny Buddy, I measure voltage of 2.2V.
Why this voltage drop occurs?
Can anyone please help me, I am doing my masters thesis?
When you put a load on your solar cells the voltage will drop somewhat, this is normal. The more current you demand from the cells, the larger the drop will be.
10.4 volts is way too large a drop, you’re pulling more current than the cells are able to cope with. What capacity are your cells? (Open circuit voltage / short circuit current / power rating?) How much h current does the sunny buddy pull if you attach it to a 12 volt power supply?
@YellowDog thank you for your reply.
I am using eight PV cells 12V/1.5W and i have tried two ways of connecting these cells.
First - all eight PV cells connected in parallel (in the brightest Sun it gave me 8-9V)
Second - 2 by 2 PV cells in series and then 4 parallel (in the brightest Sun it gave me max 18V)
I am new at this and every help is welcome.
It sounds like you have enough capacity in solar cells. Starting to wonder if something is wrong with the sunny buddy.
Next step would be to substitute a bench power supply for the solar panels and see what the sunny buddy does.
@YellowDog thanks for advice.
I’ve connected Sunny Buddy to 12V adapter (measured 12.36V). After connection on input jack is still 12.36V, and on output jack (battery and load) is 4V. From that, I conclude that everything is alright with Sunny Buddy, it’s not faulty.
From that above, can you please give me new advice if you know, what can I do with voltage drop when I connect PV cells?
It’s hard to say for sure but I think you need more solar cells wired in parallel. Try adding 4 more and see if that’s enough.
The current produced by PV cells is roughly proportional to the illumination(*), so to get the full expected power out of the cells, you need to be in full sunlight.
Please measure and report the short circuit current of your panel under the illumination conditions of your posted tests.
(*) The open circuit voltage does not depend strongly on illumination, so it is best to think of a PV cell as a current source in parallel with a diode.
