cannot understand amperage readings.

[guruji]

Hi guys is there a fault in my system bank? cause when I test my solar panel alone  it's giving me 2amp but when connected between live wire is giving me 1.2amp😕.
Cannot understand this.
Any help please?
Thanks

[tanner0441]

Hi

If by testing the solar panel alone you mean you connect the amp meter across the panel, you are imposing a dead short across the panel, when you test it in circuit there is resistance added to the circuit, but need more information.

What size panels and what rating are they? If there is a spec label on the back all the information will be on that. Also what voltage is your system?

Brian

[guruji]

Hi

If by testing the solar panel alone you mean you connect the amp meter across the panel, you are imposing a dead short across the panel, when you test it in circuit there is resistance added to the circuit, but need more information.

What size panels and what rating are they? If there is a spec label on the back all the information will be on that. Also what voltage is your system?

Brian

Thanks Brian for response.
Does it hurt the panel testing across terminals with an amp meter?
I did the panel. Made it with 35 cells 1.2w each but it' s only giving me 1.2amp with load.
Is it true that cells shoul be sealed from oxygen?
Thanks

[tanner0441]

Hi

On a low power panel I don't think it will come to much harm, the panel is big enough to dissipate any heat. The reading you get on the other hand is meaningless. You might be reading 2 amps but shorted out there is zero volts, and watts is amps times volts, so 2 times zero is zero usable watts.

I can't answer your other question I know nothing about making solar panels, but read back through this site there are pages of information on here.

What type of charge controller do you have, and did you fit a blocking diode to stop the panel discharging your battery when the sun is the other side of the planet?

Brian

[guruji]

Hi

On a low power panel I don't think it will come to much harm, the panel is big enough to dissipate any heat. The reading you get on the other hand is meaningless. You might be reading 2 amps but shorted out there is zero volts, and watts is amps times volts, so 2 times zero is zero usable watts.

I can't answer your other question I know nothing about making solar panels, but read back through this site there are pages of information on here.

What type of charge controller do you have, and did you fit a blocking diode to stop the panel discharging your battery when the sun is the other side of the planet?

Brian

Yes I did a diode. Regarding voltage it's giving me about 15.5v.
Ok I will have a look on the site.
Thanks

[oztules]

http://www.fieldlines.com/index.php/topic,145005.0.html

You should find something in there.

If the cells are matched in the panel, no harm should come from shorting them.... but if the cells have mismatched internal resistance (micro cracks in particular) then some will get very hot spots, while others don't...  and can damage the glass itself even with 3x2 cells.... may crack it  if normal glass.

The state of charge of the batteries will also drop the current if they are near charged as well.

Your short circuit current is the most current you can get , but if you look at a graph of a solar cells volts and amps, you will see you can't get that current once you let the voltage rise... the most you can expect gets less from Isc as you let the volts rise.... until you have max volts and no current at Voc.... and every where in between.

The oxygen thing I have heard of... may be some truth...... but it is more important to protect from moisture... ie humidity and condensation at night. This usually kills the home made panels that are built without EVA or special silicons.... water vapor is the enemy.

I have forgotten just how many kilowatts of  panels I have built for solar pumping, but it is over 5kw at least.... they all still work perfectly well years later.

So have fun with it.


.................oztules