Need some advice on wiring new controller to pre existing solar charging system

[TXfreeze]

The Winneabago Adventurer we have has 3 large after market Siemens panels and one small one, what loooks like came factory installed, the installed Mark PV Controller, showed Array Current at 0, I tested for current at the panels themselves and I was getting around 17 or so, I'm not sure I think they are wired in Paralel, when I was in Quartzite, I took out the controller and disconnected it and examined it, the AGC fuse for the array was not only bad, the holder was partially melted. I spoke to some folks there at the swap meet and they told me it might be the controller had a cheapy controller for $50 that may or may not work since it was a demo so I stopped by the Solar Discount place there in Quartzite and the salesman told me that before I replace the controller, that I need to determine the wattage of the panels and that most likely they are 30 amp, so far I have not been able to determine the wattage, I tried to use a inspection mirror to see if I can look under but can't see, taking one out looks to be more trouble than it's worth I can only assume each panel is at least 100 watts. I recently went to Harbor Frieght and picked up a low cost Thunderbolt 500 watt solar 30 amp charge controller, but I'm concerned about wiring it to the setup since there might be an underlying issue that caused the fuse to melt, upon examing the Thunderbolt and checking the instructions there doesn't seem to be any kind of fuse to protect it like the Mark PV has, so I would think it would be recommended to have a inline fuse at the battery, actually that was suggested to me and I do have a 25 watt inline that I can wired to the batter,y, I take it that would be to the hotwire negative side. I've considered gettng some help from a pro,. but if it's something I can D.I.Y. I'm willing to give it a go. Any thoughts?

 

[Kevin D Pem]

What you need to know:

Square area is watts. A panel 5.5ft x40" will be about 250watt. 100watts will be about 40" x 3 ft. Number of cells on the panel tell you the voltage.. 60 cells = 48voc. Or about 30 mmp. mpp.
House panels come in 60 and 72 cell varieties.

If your panels are that large the controller you got will fail. When I say that large I talk cell count.

The controller is likely a PWM and is very inefficient. I would return it and buy a MPPT controller.

Where are you now? I ask because I might be able to direct you to a source other than online.

 

[TXfreeze]

What you need to know:

Square area is watts. A panel 5.5ft x40" will be about 250watt. 100watts will be about 40" x 3 ft. Number of cells on the panel tell you the voltage.. 60 cells = 48voc. Or about 30 mmp. mpp.
House panels come in 60 and 72 cell varieties.

If your panels are that large the controller you got will fail. When I say that large I talk cell count.

The controller is likely a PWM and is very inefficient. I would return it and buy a MPPT controller.

Where are you now? I ask because I might be able to direct you to a source other than online.

I measured one of the panels and it's 40 x 26 inches and 12 by 6 cells, so 72, so I guess they are 100 watts each, that said do I still need to return the one I have and get a MPPT controller, I have the Thunderbolt all hooked up minus one array wire I'm holding off till I'm sure. Also I don't think that small panel is in the array, but I have tested it and it has some wattage. By the way I searched to see what forum I should post and briefly saw your solar related post, so I had a feeling you might be the one to reply and sure enough here you are, anyhow I appreciated your help both here and and with the water heater issue, which I’m glad to say is now resolved. On a second thought what if I connect back PV Mark, it still will hold the fuse, use the inline fuse in case something should go wrong, it would be good if I can figure out what caused the fuse to melt.

 

[Kevin D Pem]

Measure the open circuit voltage. This is likely 50+ volts. Your controller will have to handle that voltage(voc). The hf controller handles what 30v max. Your hf controller will smoke. That may well be what happened to the last one.

PWM controllers won't bring down the voltage from 50+ volts to a 12v System. MPPT is the only way to charge a 12v battery bank from any voltage above say 21v panel voltage.

Check San Tan solar s website for controllers, it's in Gilbert, AZ.

 

[TXfreeze]

I measured Open Circuit and it's 20.53 volts also measured open circuit shows 0.708 amps one of the wires sparks when I measure it, is that normal? I plugged the two solar array leads wires into the controller but it shows 0 amps, seems like something is wrong there, so given know that do you think I still need a MPPT controller?

 

[Kevin D Pem]

Not with 20v panels. Are you sure you counted 72 cells? Put up a picture of the panels.

 

[TXfreeze]

Not the best shot, I realize the bird crap has to go, but we’re here at the gulf and lots of gulls around here.

 

[Kevin D Pem]

Not the best shot, I realize the bird crap has to go, but we’re here at the gulf and lots of gulls around here.

20v??? Your panel has a bad diode or broken trace. And no That controller would fry with a working panel like that.

 

[Kevin D Pem]

This panel produces 36voc

This controllers

handles 4 of those panels on a 24v system it will handle 2 panels on 12v system. These are 250watt panels and the controller is a 60 amp controller .

The controller cost me 120 shipped from Amazon. The panels were used and cost me 50 from San Tan solar in the Phoenix area.

 

[TXfreeze]

Not the best shot, I realize the bird crap has to go, but we’re here at the gulf and lots of gulls around here.

20v??? Your panel has a bad diode or broken trace. And no That controller would fry with a working panel like that.

I have no doubt something is wrong, but as you may recall in my original post when I last checked each of the 3 panels ceach was measuring 17 or so at the panel, so your saying each panel should be putting out at least 20 volts? So one panel with a bad diode would compromise the whole array, but does that mean all the paenls need to be replaced? If there is a chance that one one or more of the panels is good I would rather not go to the trouble of replace them, not to mention were on a fairly tightt budget at the moment. We don't do much dry camping so I wonder if it's worth it, I justt would like to have this sysstem working when we sell the motorhome, whenever that is.

 

[Kevin D Pem]

If only one panel is bad take that panel out of the circuit. A panel with that many cells should be putting out about 56 volts.

Yes if one is bad it will bring down the system. However you still need a controller that will handle the panel. The controller I showed you is the best for the money I have found. Another place you can find it is on aliexpress.com it has been rumored that they only make the 60amp controller and sell it as 30,40,and 60amp but I have not confirmed that.

I do understand the money issue, I work around it everyday. I have been volunteering my time to help others with financial concerns set up solar so they can reduce costs while off grid. That is what I do!

 

[TXfreeze]

If only one panel is bad take that panel out of the circuit. A panel with that many cells should be putting out about 56 volts.

Yes if one is bad it will bring down the system. However you still need a controller that will handle the panel. The controller I showed you is the best for the money I have found. Another place you can find it is on aliexpress.com it has been rumored that they only make the 60amp controller and sell it as 30,40,and 60amp but I have not confirmed that.

I do understand the money issue, I work around it everyday. I have been volunteering my time to help others with financial concerns set up solar so they can reduce costs while off grid. That is what I do!

Apparently the smaller panel was connected, I took readings with it connected., each panel is around 20.7 or so, after disconnecting it, I'm Still getting 20 open circuit, how do I figure out which is the faulty panel? Is it possible it's not a panel issue but something shorted in the panel wiring? I appreciate your help and how you help others.

 

[Kevin D Pem]

Disconnect wires at panels and check each panel out of circuit.

 

[TXfreeze]

The connectors on each panel are under the panel, requiring unmounnting them, is there another way? Right it’s fairly overcast so I will have to wait to test.

 

[Kevin D Pem]

The connectors on each panel are under the panel, requiring unmounnting them, is there another way? Right it’s fairly overcast so I will have to wait to test.

Yes if they all3come in the RV,

 

[TXfreeze]

Yes if they all3come in the RV,

I don't understand

 

[Kevin D Pem]

I don't understand

hard for me to use the phone so I cut it short and then sometimes you ge a cryptic response.

if the connections are inside the coach then you can separate them inside and measure the voltage there. If the junction is in a box on the roof do it there. No matter you will have to separate the panel connections to measure the voltages, and isolate the bad panel.