solar powered air pump

Posted by Robert Field on June 30, 2008, 03:15:49 PM

I have used two solar panels to power an air pump to create an air lift system that circulates water for shellfish aquaculture. These two panels are connected to two batteries in parallel, then to an inverter and to an AC air pump. It has worked OK in the past, but this year the inverter has faulted and when I check the voltage it is up over 16 volts. The panels are about 8 years old. Does their ability to maintain the right voltage degrade over time? Can an automotive voltage regulator be installed to control this?

Posted by John B on June 30, 2008, 05:12:00 PM

Re: solar powered air pump (Reply #1)

You will have to give us more details, but it is unlikely that there is anything wrong with your panels. A reading of 16V (open circuit) would be normal for a nominal 12V PV panel.

Connecting the PV panels directly to your batteries without a charge controller may eventually damage your batteries, but it looks to me like you just had an inverter failure.

Posted by Robert Field on July 02, 2008, 09:13:00 AM

Re: solar powered air pump (Reply #2)

John,
Thanks for the reply. As far as more specifics, the two panels are rated at 75 watts and 4.4 amps. The maximum inverter output is 350 watts. The air pump is 115 v AC and 43 watts. I checked the specs on the inverter and the high voltage fault is 15v so it looks like it was doing its job to cut out when the voltage went up over 16. I guess I need to get a charge controller. The short circuit amps for the pv's are 4.8, so it looks like I need a 15 amp controller.
Bob

Posted by John B on July 02, 2008, 01:50:52 PM

Re: solar powered air pump (Reply #3)

Robert,

Maybe it is a bad or loose connection between the battery terminals and the pv panel. I would have expected that the batteries would have prevented the voltage from rising above 15V. That's why I suspected a bad battery or faulty inverter when you were able to measure 16V+ if the batteries were still connected to the pv panels. A charge controller would still be a good investment for long-term life of your batteries.

Posted by Robert Field on July 03, 2008, 11:48:18 AM

Re: solar powered air pump (Reply #4)

John,
I'll check the terminals, and the controller is on it's way. Thanks for your help.

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solar powered air pump

Posted by Robert Field on June 30, 2008, 03:15:49 PM

Posted by John B on June 30, 2008, 05:12:00 PM

Posted by Robert Field on July 02, 2008, 09:13:00 AM

Posted by John B on July 02, 2008, 01:50:52 PM

Posted by Robert Field on July 03, 2008, 11:48:18 AM

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