Solar system not fully charging battery

solmon2005

I have two 120 W panels rated 12 V connected in parallel , a PWM controller and 100 Ah tubular battery.

My battery is not at all charging completely as the controller indicates around 30% charge only. I used to get around 6 hours of good sun light at present.

I checked the current from the panels to controller, it is only delivering 3 A in total from both panels, even if I disconnect any one panel, the current remains the same.

The voltage output is around 15 V for both panels when connected to controller, I have checked by replacing my controller with another one, but it also gives the same result.

My battery is fairly new one. I got around 6 A from individual panels when checked in short circuit mode.

I can't understand why the panels are not delivering current to battery as if it seems like battery does not require it.

littleharbor2

Could be a polarity problem. Are you sure you're parallel wiring your panels? If you series wire your panels you raise the voltage but leave amperage at, say 6 amps, best case. Now you run this 24 volts, actually about 36 volts into a 12 volt battery and you're only going to get 1/3 of the panel's output. 

What is the voltage and amperage coming from the panels when disconnected from the controller?  you should see about 20 - 21 volts and up to 12 amps when oriented somewhere toward the sun. If these panels are laying flat on a level surface, at least test them around mid day. Actually all you need to confirm polarity is if you are getting an open circuit voltage above 22 volts, then you may have series wired them.

 The above may not be the case but it sounds like it to me. If not you might have a bad controller. You always want to connect the battery first, panels second to your controller. If you connect the panels first your controller may have booted up thinking you have a 24 volt system.

 Hope this helps.

mcgivor

A 12V nominal panel should have an open circuit voltage VOC somewhere in the region of 21V with a voltage maximum power VMP around 18V. A PWM controller will pull the voltage down to slightly above battery voltage, so if you're seeing 15V at the solar input and the battery voltage is around 14.4V, the current would be reduced because the controller would be in PWM mode, this is similar to absorption with a MPPT controller where current is reduced as the battery approaches full charge. Can you measure the battery voltage as well as post the panel specs, additionally the controller specs would be helpful 

solmon2005

Thank you all for your response, i have once again ensured that the panels are wired in parallel.

The open circuit voltage from panel just before entering into the controller is about 19V.

And the short circuit current at the same point is 9.8A.

My battery voltage is 11.9 V

I have checked my battery by charging it with a mains charger and the battery happily takes 10 to 13A.

I have two PWM controllers one is a china made which i thought may be faulty, so i purchased another 'Sukam' branded controller, but both shows same result...

Both controllers are 12/24V auto switching and i always ensures to connect battery 1st.

mike95490

Maybe the battery is not as new as you thought it was.   Can you read the date codes ?

solmon2005

> @mike95490 said:
> Maybe the battery is not as new as you thought it was.   Can you read the date codes ?

Battery purchased on 16th December 2017. And is having a warranty of 3 years.> @mike95490 said:

mike95490

Not the purchase date, but the Mfg date, coded somewhere on the battery.  When you buy a battery, it's often sat a couple months in transit or at the dealer, and may or may not have had charging top ups in the meantime.  It could have been half dead from sulfation when taken off the showroom floor.