Panel Problem

Pigman
Pigman Registered Users Posts: 2
in Off Grid Solar & Battery Systems #1
I'm a newby to this forum, and hope I can get some information from those with vastly more knowledge and experience in the solar area. We have a 40' Class A RV that we use about 6 months a year. It has one factory installed solar panel (around 120W) and I am going to add additional panels to allow us to operate in remote areas while still running our 21 cu ft household refrigerator/freezer and other systems. I had been using an additional 110w solar panel on the ground to supplement the roof mounted one, but we have decided to upgrade to a Morningstar controller, new heavier wiring, and 2 additional Kyocera 140w panels. We have sufficient batteries to take the power (10 6V AGM's) and have a 7500w diesel generator to charge them when needed, but when I started to put the modified solar system in I found one of my older panels is giving me some strange readings.

When I hook up the Photowatt M-PW6-110 to the Morningstar, I get an indication of voltage, but no current flow. Without the panel hooked up to anything my voltmeter shows 17.4V, and when I just put a 10w 12v halogen bulb as a load, voltage goes to 12.7V but no current flows (no light and no current on the meter). I checked the panel diodes and the meter shows flow in one direction, and none the other way, but at that point my troubleshooting expertise runs out.

Anyone have a clue what's going on? The panel is not damaged and has never been dropped or abused. The box on the rear of the panel appears to be potted, so I don't know where to go from here. Thanks in advance for any help.

John
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Comments

  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Panel Problem

    Hi "Pigman" Welcome to the form!
    If the panel voltage drops slightly when the light bulb is connected, yet the bulb does not light, (assuming the bulb is good) this indicates a high resistance (very poor, possibly corroded connection or wire) somewhere between the panel and the bulb.
    What current output in amps do you measure in full sun, right at the panel terminals with nothing but your meter connected to that panel? Very little current indicates a bad panel/meter/or leads.
    Re panels needed to run all your loads - - you must first determine what your actual daily consumption is for each appliance, using a Kill-a-watt meter or similar, then add it all up. Then, knowing your actual needs and also your actual location in earth, folks here on the form can advise what panel wattage you will need.
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  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    #3
    Re: Panel Problem

    The Morningstar - and nearly all charge controllers designed in the past 10 years or so - have to have a battery attached to the output before they will turn on.

    The LOAD output on controllers actually comes from the battery, not the panel. With no battery, nothing happens.
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  • Pigman
    Pigman Registered Users Posts: 2
    #4
    Re: Panel Problem

    With the panel hooked to the Morningstar and the Morningstar hooked to the batteries, the Morningstar remote meter reads battery voltage and zero amps. When I hook up a new Kyocera 140W panel the same way, I get battery voltage and between 6 and 7.5A, depending on sun and panel angle, and all other expected readings. A check with 2 different ammeters (one a cheap 10A digital, and the other an analog -50, 0, +50) gives me the same info. No corrosion in the panel box and all connections checked multiple times. I'm thinking the panel went bad, but don't have a clue why I get the Vimp at 17.2 without it being hooked up. I'd expect an open to give me Vimp=0

    John
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Panel Problem

    the panel may still be putting out current, but it may be a very small current in the ma or ua area. it does sound like it may have gone bad.
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