diy 36cell panel only generating 0.5 amp. help.

[Sunking]

if the isc and il is different, does that mean resistance is only external and not inter cells?stance?

I have no idea of what il is. It is not an accepted term. I suspect you mean Imp (Current @ maximum power point). What is likely escaping you is solar panels are current sources, not voltage like a battery or generator. Unless you have a extensive knowlege of electric circuits there is no way I can explain it to you in a way you would understand.

From a DIY POV there are only two test measurements you can make. For that matter only the same two measurements a professional can make in the field. Those two are Voc (Voltage open circuit), and Isc (Current short circuit). From those two measurements you can determine if the panel is operating correctly or not. As a DIY panel you cannot determine accurately the Vmp (Voltage maximum power), Imp (Current maximum power), and Pmax (Power at maximum power point), but you can estimate them.

So here is where I am going with this. If you have a 36 cells panel with all the cells in series using 6 x 6 cells that are rated at 5 amps, and you measure a Voc of around .67 volt x 36 cells = roughly 22 to 24 volts, and measure around 5 amps Isc then you know your panel is working properly. From that you can guestimate the Vmp to be around .5 volts x 36 cells = 16 to 18 volts, Imp to be .9 x 5 amps (Isc reading) = 4.5 amps, Pmax = Vmp x Imp = roughly 72 to 81 watts.

As I stated earlier you need to first determine the State of Charge of your batteries because I suspect you are chasing ghost and just spinning your wheels chasing a problem that does not exist.

[thupten]

when i measure the isc of the panel, its at about 5amps. but the illuminated current is only 1.7amps. can someone explain to me what makes this difference? I read here that high resistance does that. does that mean that resistance when on Isc and resistance when connected to battery is different? Sorry, if this doesn't make sense, my background is not from electrical/electronics.

if the isc and il is different, does that mean resistance is only external and not inter cells?stance?

[Sunking]

i am using awg 12. there is a loss from 5 amps to about 3.5 amps when tested short circuit near the panel vs short circuit test of panel near charge controller about 50ft of wire. but i don't understand how my 3.5 amps panel generated current becomes 1.7 amps charge current after passing through the charge controller. even after considering 1.7 amps on single panel, for each additional panels connected in parallel is only incrementing 0.1amp, not 3.5 amps nor 1.7 amps.

OK Do I understand you correctly you have 2 panels in parallel with each rated at 17 volts @ 5 amps? If correct your total current would ideally be about 10 amps under full charge demand. So I base my next comment on those assumptions.

Although 12 AWG wire can safely handle 10 amps, it is grossly undersized for a 1-way distance of 50 feet. To maintain 2% or less voltage drop at that distance requires a minimum # 4 AWG copper conductor

Lastly what is the State of Charge of the batteries? If it is near 100%, or in other words near fully charged, the batteries will not draw much or any current whatsoever. I suspect you are chasing ghost. Disconnect the battery from everything, let it rest for 4 or 5 hours, measure the voltage and report back.

[thupten]

what condition makes short circuit current Isc much larger than illumination current

when i measure the isc of the panel, its at about 5amps. but the illuminated current is only 1.7amps. can someone explain to me what makes this difference? I read here that high resistance does that. does that mean that resistance when on Isc and resistance when connected to battery is different? Sorry, if this doesn't make sense, my background is not from electrical/electronics.

i am using awg 12. there is a loss from 5 amps to about 3.5 amps when tested short circuit near the panel vs short circuit test of panel near charge controller about 50ft of wire. but i don't understand how my 3.5 amps panel generated current becomes 1.7 amps charge current after passing through the charge controller. even after considering 1.7 amps on single panel, for each additional panels connected in parallel is only incrementing 0.1amp, not 3.5 amps nor 1.7 amps.

[oakdale]

Wiring Problems?

when 2 panels are separately checked, they have 1.77 amp each. then i connected both of them in parallel ( positive to positive and neg to neg), then connected to the controller. the controller only reads 1.90amp. its not adding up correctly.

Just a guess, but maybe you should re-check your wiring. Check that all the connections are good and that you're using a large enough wire gauge for the length of the wire. What gauge wire are you using? How long is wire run one-way between the panels and the controller?

I still think that anyone who makes their own panels is braver than I am. Too many connections for me. Too many opportunities for problems.

[thupten]

How are you reading the Isc? Did you disconnect the panel and measure it directly under noon sun on a bright clear day?

yes, i disconnected the panel from the controller. the panel is connected only to the dmm while measuring the current. its bit cloudy, but i have it under as bright light as possible during the noon time.

i found another problem i could not understand. when 2 panels are separately checked, they have 1.77 amp each. then i connected both of them in parallel ( positive to positive and neg to neg), then connected to the controller. the controller only reads 1.90amp. its not adding up correctly. what might be the problem? please help. the controller is showing bulk charging.

[Sunking]

my dmm also seems to have problem. the 10a dmm reads more than 5 amp in short circuit test. but clamp dc current shows less than 0.1amp.

How are you reading the Isc? Did you disconnect the panel and measure it directly under noon sun on a bright clear day?

[thupten]

is there a way to find out which cell(s) in the panel is bad? I panel is encapsulated and I cannot open each cell to find out if it is the broken one. the cells are in series of 36. thanks.
my dmm also seems to have problem. the 10a dmm reads more than 5 amp in short circuit test. but clamp dc current shows less than 0.1amp.

[Naptown]

sounds like a bad battery to me

[thupten]

It is Isc current short circuit test. It is a test to verify the panel is producing the rated current. Most likely you have a bad cell or solder joint in the panel.

the digital multimeter with 10A capability shows 5.75 amp. I put red probe in 10a socket and black probe in com socket, and then connected to the solar panel in sunlight. The wire going into the controller has 4amp but the controller software shows only 1.26 amp charge current. The single 12v battery is at 11.5 volt. It has 13.95v when full.

[Sunking]

It is Isc current short circuit test. It is a test to verify the panel is producing the rated current. Most likely you have a bad cell or solder joint in the panel.

[thupten]

i have already encapsulated the panel.

Have you tested short circuit current of the whole array, individual panel, and individual cell? A panels current is as strong only as its weakest cell.

I will check for short circuit. I have already encapsulated the panels, so I cannot check for individual cell. The voltage for each panel is about 18 volt. So there is no problem in voltage. If there is short circuit, would the voltage show correctly?

[axis11]

Have you tested short circuit current of the whole array, individual panel, and individual cell? A panels current is as strong only as its weakest cell.

[thupten]

batteries are not full.

If your batteries are almost full, you wont get much amps from the panels.

hi axis,
thanks for reply. the amp test was conducted when the pwm controller was in bulk charge stage. i have a tristar which shows the charge stage as bulk,absorption or float. as far as i know, during bulk charge, batteries are not full and maximum amp should be used for charging. but my system is not doing so.

[axis11]

If your batteries are almost full, you wont get much amps from the panels.