Tied 36 .5volt cells in series and i'm getting 30 volts output. please help

[cyberfast]

Tied 36 .5volt cells in series and i'm getting 30 volts output. I should be getting 18 volts. I'm testing this straight off of the cell configuration. I do have a charge controller but i am wondering if that voltage will fry the controller. I will be charging 12 volt battery with this system. I don't know if this is normal without a load. I have enough cells to build 15 of these panels. Should i remove some cell? Won't that drop the watts? This panel should be 63 watts with 36 cells. Please help. Thank you.

[Sunking]

I take you you are measuring at open circuit voltage? If so you will need to have a MPPT controller with a 12 volt battery.

[cyberfast]

open circuit

if you mean nothing connect to the solar cell then yes i am testing it in open circuit. I have the controller. My ? is will 30 volt fry a 12 volt controller?

[Sunking]

if you mean nothing connect to the solar cell then yes i am testing it in open circuit. I have the controller. My ? is will 30 volt fry a 12 volt controller?

Quite possible if it is a PWM controller. MPPT no problem. Check your controller spec for maximum Voc

FWIW if you do have a PWM controller and it can handle 30 Voc on a 12 volt battery you will will loose 60% automatically of your panel wattage. MPPT no problems.

Example lets say your panel is rated 60 watts with the 36 cells, you will turn it into a 24 to 30 watt panel. Loose 10 of those 30 cells and you have a 40 watt panel that will produce the same 24 to 30 watts.

A typical 12 volt panel has a Voc of around 20 to 22 volts (you have 30) and a Vmp of around 16 to 18 volts.

[cyberfast]

ok so should i remove 10 cells

Quite possible if it is a PWM controller. MPPT no problem. Check your controller spec for maximum Voc

FWIW if you do have a PWM controller and it can handle 30 Voc on a 12 volt battery you will will loose 60% automatically of your panel wattage. MPPT no problems.

Example lets say your panel is rated 60 watts with the 36 cells, you will turn it into a 24 to 30 watt panel. Loose 10 of those 30 cells and you have a 40 watt panel that will produce the same 24 to 30 watts.

A typical 12 volt panel has a Voc of around 20 to 22 volts (you have 30) and a Vmp of around 16 to 18 volts.

if i remove those cells then i can make more panels to make the watts up but why would the cells that are max rated at .5 volt make 30 volts with 36 in series. i can't find no spec on the charge control for the voltage all i found is 105 max watts and 7 amp max its a pulse controller cut out at 14.2 cut in at 13.0 .i have a bunch of these. I'm really sorry about bugging you about this. I'm pretty good with math but this one is not making sense. i tested each cell and i had a reading of .42 to .52 volts but ran in series i got 30 volts. just don't make sense. is it possible i got a very good batch of cells? Thank You so much for the help.

[cyberfast]

vmp

what does that stand for?

[russ]

Home Power has a very good document that explains many PV panel terms -

1) PV module comparison http://homepower.com/view/?file=HP134_pg50_Sanchez

Russ

[cyberfast]

Home Power has a very good document that explains many PV panel terms -

1) PV module comparison http://homepower.com/view/?file=HP134_pg50_Sanchez

Russ

thanks allot for the link. this will help me out when i will be buying my next panels.

[Sunking]

what does that stand for?

Voltage @ Maximum Power

A solar cell has 5 specifications of interest to designers and 2 for a home owner.

Voc = Voltage Open Circuit. This is a static test of the voltage of the panel pointed directly into bright sun light with no load connections and one a homeowner can perform to check against factory specs. A typical solar panel made for 12 volt panels will measure around 22 volts

Vmp = Voltage Maximum Power. This is a factory test only, a homeowner does not have access to the equipment needed to accurately measure Vmp It is a measurment of voltage of the panel when it is producing maximum power at a specified irradiate input. A home owner can take measurements during the day to see if th epanel is loading properly and get an idea his/her panel is producing power or not and to check for malfunctions. Typical Vmp for a standard 12 volt panel is around 16 to 18 volts and will always be less than Voc

Imp = Current @ Maximum power. Again a factory measurement

Isc = Current Short Circuit. This can be done by a homeowner who knows how to operate a meter capable of measuring the intended current of a single panel or a string of series panels but can be dangerous. So only proceed if you fully understand the risk and principle. Otherwise on a large string array death and injury can occur. Th epanel is pointed directly into noon day sun and the terminal shorted out either through a shunt meter or a wire loop when a clamp-on hall effect meter is used. This current will be higher than Imp and used to check if panel is operating properly.

[cyberfast]

thank you

Voltage @ Maximum Power

A solar cell has 5 specifications of interest to designers and 2 for a home owner.

Voc = Voltage Open Circuit. This is a static test of the voltage of the panel pointed directly into bright sun light with no load connections and one a homeowner can perform to check against factory specs. A typical solar panel made for 12 volt panels will measure around 22 volts

Vmp = Voltage Maximum Power. This is a factory test only, a homeowner does not have access to the equipment needed to accurately measure Vmp It is a measurment of voltage of the panel when it is producing maximum power at a specified irradiate input. A home owner can take measurements during the day to see if th epanel is loading properly and get an idea his/her panel is producing power or not and to check for malfunctions. Typical Vmp for a standard 12 volt panel is around 16 to 18 volts and will always be less than Voc

Imp = Current @ Maximum power. Again a factory measurement

Isc = Current Short Circuit. This can be done by a homeowner who knows how to operate a meter capable of measuring the intended current of a single panel or a string of series panels but can be dangerous. So only proceed if you fully understand the risk and principle. Otherwise on a large string array death and injury can occur. Th epanel is pointed directly into noon day sun and the terminal shorted out either through a shunt meter or a wire loop when a clamp-on hall effect meter is used. This current will be higher than Imp and used to check if panel is operating properly.

you are right about the voc once a load was put on the panel (charge controller) it drop the volts down to 18.8 volts. thanks so much.