hi,
Ok,
Have you measured the actual current drawn by the Arduino when the panel was in the Sun.?
To check that the Arduino does not have a internal short circuit.

It is also possible that the panel is faulty, have you tried a resistive load on the panel, 100R to 200R.??

E

Update:
Have you got the panel Vout connected directly to the Arduino Vdc input.!!!!
If the panel voltage has risen to well over 12Vout, you may have blown the onboard voltage regulator.

The onboard regulator is supposed to work up to 12Vin, I use 9Vin.

 

I have just put 200 Ohm resistor across solar panel. The voltage drops down form 11V to 2.6V and only 1mA of current seems to be flowing. Also, when I put a scope in series to measure the current, voltage drop changes from 2.6V to 3.3V. I will do this test tommorow when its sunny to see what difference does it make

 

OK,
What are the dimensions of the panel Width * Length??

 

As I said previously - measure the short-circuit current of the panel under the lighting conditions you are trying to use.

What type of voltage regulator are you using between the panel and the Arduino?

 

Sorry I dont have ruler with me cant tell you exact dimensions but its bigger than my 13inch mac screen.

 

I am not using any voltage regulator as I thought the voltage regulator built in arduino will be enough. I am connecting Solar panel directly to Vin and GND to arduino uno

 

I have just put 200 Ohm resistor across solar panel. The voltage drops down form 11V to 2.6V and only 1mA of current seems to be flowing. Also, when I put a scope in series to measure the current, voltage drop changes from 2.6V to 3.3V. I will do this test tommorow when its sunny to see what difference does it make

This cannot be correct. If you are getting 2.6 V across a 200 ohm resistor, the current must be 13 mA. This equates to 33.8 mW, which suggests the illumination on the panel is something around 0.3% of the test conditions normally used for panels. It may be that the series resistance of the current meter you are using is causing a large error. The calculated value from the voltage across the 200 ohm resistor is probably much more accurate.

I don't know what you mean by "put a scope in series to measure current."

===
I didn't realize the Arduino had a regulator on the board. As long as it can handle the open-circuit voltage of the panel, all should be well. Some "low dropout voltage" regulators may not have adequate rating, so it is worth checking the datasheet for the regulator.

 

hi,
Those dimensions and individual panel count match with a 10Watt panel, I suspect your panel is faulty.?
E

 

EDIT - just noticed UNO mentioned in a previous post.
What version of the Arduino are you using?

EDIT2 - spec is 20 V maximum for supply

 

I am not using any voltage regulator as I thought the voltage regulator built in arduino will be enough. I am connecting Solar panel directly to Vin and GND to arduino uno

Does the Arduino still work OK, with a 9V power supply.?? [ check the onboard voltage is 5v]

 

Hello,

Wich arduino are you using?
There are many different boards:
https://store.arduino.cc/arduino-genuino/boards-modules

Seen that you use an UNO.
The specs for the powersupply are:
Operating Voltage 5V
Input Voltage (recommended) 7-12V
Input Voltage (limit) 6-20V

Bertus

 

I am using Arduino UNO board. Arduino seems to be working with 9V supply. Getting 4.95V at 5V pin and 3.3V at 3.3V pin. Im also confused why im getting only 1mA current accrors 220 Ohms resistor.

 

Hello,

The current must go THROUGH the resistor and is NOT accross the resistor.

bertus

 

Yes that is what i meant when i said i put a scope in series not in parallel. I made a break in connections and put a scope in between. Then the voltage dropped to 3.3V and only 1.1mA current measured for some reason

 

Hello,

What scope do you have?
The input impedance of a scope can be very high.
Many scopes will ahve an input impedance of 1 MEG Ohms.

Bertus

 

https://cpc.farnell.com/aim-tti-ins...YTMoOXKUSFA5B7s3t-eDlAFIVKBTOEXoaAv99EALw_wcB
I am using this multimeter

 

Thank you everyone for quick responses! Tommorow I will try measuring the current and voltage outside and see what results I get and will posts results here.

 

Hello,

That is a DMM (digital multi meter) and not a scope.
When that is plugged for ampere measurement the input resistance will be low.

Bertus

 

Im also confused why im getting only 1mA current accrors 220 Ohms resistor.

Hi zazas,
I would say that is either due to lack of sufficient sunlight illuminating the panel or the panel is defective.

E

 

I have some numbers and thoughts about light.

Right now, it's two hours before the sun is highest in the sky outside my office, and my lux meter shows nearly 100 klx (100,000 lx).

I can measure 300 lx here in the office, in mixed lighting, but away from direct sunlight.

This would mean that a 10W Solar Panel, within my office, would get 0.3% of rated light and maximum give 30mW.