solar panels (again)

pessimist

pessimist

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I'm sure I've seen threads on this but can't find one now, so apologies in advance. I have two solar panels (80 w) marked as 21.6v open circuit. I'm measuring c19.5 volts and am measuring around 3 amps at the batteries with the panels wired in series. Are the panels knackered and if so what's the current advice, mono or poly?
Thanks
 
Voltages sound reasonable. You're not going to get the open circuit voltage whilst drawing 3A.

Are you sure they are in series?

Also what is the battery voltage?
 
If they are wired in series the voltages are way off, sounds more like they are wired parallel.

Where are you taking your measurements from ?
 
Do you have the voltage when the panels are wired in series, and the the V taken from the +ve and -ve at opposite ends ?

Does the output go through a controller to the batteries ? If Y, then is it PWM or MPPT ? Any data output from the controller ?


What is your feeling about the state of charge of the batteries ? Single, double, triple layout ? Total Ahr capacity ? Type (lead, AGM, etc) ?
 
sarabande said:
Do you have the voltage when the panels are wired in series, and the the V taken from the +ve and -ve at opposite ends ?

Does the output go through a controller to the batteries ? If Y, then is it PWM or MPPT ? Any data output from the controller ?


What is your feeling about the state of charge of the batteries ? Single, double, triple layout ? Total Ahr capacity ? Type (lead, AGM, etc) ?
Click to expand...


Voltage around 38 when in series.
Controller is MPPT.
Batteries are lead, 2*105, about 20amps discharge so say 10%
 
That's beginning to sound as if the panels are OK, but the charge of 3A very much depends on the state of charge of the batteries, and their ability to accept charge (i.e. whether they are in good condition or otherwise)
 
Not sure what problem you think you have. Is it just that you think 3a is low ? If so, at Sarabande said, that will depend upon the SOC. I came back to the boat today and my 260w installation was putting 0.5a into the batteries, because they were pretty much charged. Turn a few things on and the amps from the controller go up to match, but the amperage going into the batteries is still 0.5a.
 
PaulRainbow said:
Not sure what problem you think you have. Is it just that you think 3a is low ? If so, at Sarabande said, that will depend upon the SOC. I came back to the boat today and my 260w installation was putting 0.5a into the batteries, because they were pretty much charged. Turn a few things on and the amps from the controller go up to match, but the amperage going into the batteries is still 0.5a.
Click to expand...


Thanks for that. I was concerned by two things
As you correctly surmised I thought that 3amps was rather low after around 10% discharge. Last year I was getting around 6amps having spent the same number of amp hours, If I understand correctly changing the batteries for new ones means that the same number of spent amp hours represents a lower percentage discharge and therefore requires a lower charge rate?
My second concern was the lower than expected open circuit voltage.

If I have no problems I am delighted and apologize for wasting everybody's time.

Thanks again,

Colin
 
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