Solar charging problem driving me nuts

[Roly]

I recently have been readdressing problems with my solar installation that I started over two years ago. Between then and the present life changes intervened and caused the project to be deferred. I have 2 ea 100 watt panels on the roof, a Bogart Industries PWM controller (MPPT preferences notwithstanding) and their very good programmable TM monitor. The wiring to the controller is 8 AWG PV cable, and from the controller to the batteries is 4 AWG, both positives fused at 30 amps.

The batteries are newer Vmaxtanks 125 AH group 31 AGM's, fused at 200 amps, brought inside the coach as per Mr. Blue. I removed the LVD and put the controller, shunt, Blue Seas 7622 combiner, and an on/off switch to the brown box, near the batteries, see a photo. I relocated the 50 amp fuse there too, and the brown box has a Progressive Dynamics 4645 inside. The switch and combiner are to the right, out of the picture. I took the picture before I cleaned up the wire routing. I also replaced the chassis ground with 1/0 cable in anticipation of running 1/0 to the start battery.

In the course of doing all this I hoped to find and correct the fault that stopped the panels from charging the batteries. I could previously see 21 volts from the panels at the disconnected panel positive, but no amps would pass through the controller to the batteries. When hooked up to the controller, all I saw (see) is the battery voltage. This even though I discharged them some down to 12.7 or .8. I communicated with Bogart Industries and performed tests, and eventually was sent a controller replacement, even though the tech said it might not address my problem, as it seemed to be some fault other than the controller.

This was completed a couple of days ago, I inserted the 30 amp fuses and YAY, I saw solar charging. It stopped a few hours later when the sun set, and would not charge the next day....just like the original problem. I ran the engine and saw in the monitor big stupid amps charging. I tried the shore power, and saw charging, I ran the generator, and saw amps charging...but no solar amps.

It seems impossible, now that it worked for a few hours one day, for it to have quit the next. All fuses are OK, this should work, but does not.

Any thoughts here?

Thanks, Roly

[Blue~Go]

Geez that doesn't sound half aggravating

I read through once - fairly quickly - and it sounds like you did everything right with good components (and good future planning too). So what gives.

Even more mysterious it worked once.

Can you say a bit more about the panels? I will look more closely at your photo but the one time I had a "no amps but yes voltage" problem (granted mine was on a system that had worked fine for months so that made it easier) it was a panel problem. What had happened was the diode box in one of my panels (the "box" where the wires come out of the panel) had melted down. At that point I had full voltage but nearly no amps.

Like you I suspected the controller and I was set to get a new (warranty) Morningstar, but then I did some more experimenting and found that if I separated the panels (I also had two 100 watters) then one would work and the other wouldn't. Then I noticed a funny smell and saw the melted diode box. So I called off the Morningstar replacement and instead got a new/warrantied panel.

I don't know if there can be an intermittent failure - and I'm also less familiar with PWM and what voltages you might see, but it might be worth isolating one panel at a time to see if that yields any clues?

BTW mine were the failure prone "flexible" panels. I babied them but eventually (after more failures) just went to rigid panels.

[Roly]

I obtained the two rigid HQST 100 watt panels about three years ago. It appears that my model has been superseded by somewhat smaller 100 watt panels on Amazon now. I read about 19 or 20 VDC on each, having opened all the MC4 connectors to ring out the cables. All the connectors looked good, I have no megger to check insulation resistance, but verified continuity. The 8 AWG PV cable is about as robust as I could get. The Bogart support tech, Kedar, thought that maybe the panel connections could have some problem. Other than that, the Bogart Industries TM 2030 monitor, where their solar controller is programmed, is one of very few remaining things that could be at fault.

Photo:

download/file.php?mode=view&id=5303

I certainly agree that the fact that it worked for a few hours is a mystery.

Doug Taylor

[chin_k]

The alternator, shore power, and the gen set are charging the battery without the solar controller. So just because they are working, it is independent of your solar charging problem. If I have similar problem, I would make sure the solar panels are working. Voltage *and* amp need to be sufficient for the charge controller to work. Many times people do not test the output of the panel, and spent unneeded time in troubleshoot the wiring and controller.

Keep in mind that the following is an arm-chair suggestion, so I would like someone else to tell me if it will work or a dumb idea...
1, disconnect the panels from each other, so you can eliminate the dependence. I assume you are using a 12 V mode on your controller, not 24V
2, Attach a vehicular light, or other resistive load that can handle the voltage and amp generated by your panel under test. If it get warm/light up, then use ammeter to measure the current. Look at the specification of the panel, and use a ammeter or multimeter that can deal with the current... you don't want to burn out a nice meter or blow the fuse. Sometimes, people just attach the ammeter to the panel output directly, without the load, but you may want to do this early in the morning, or later in the afternoon, or cover the panel with plywood (so you can control how much it generates) if you do not feel confident with the current and how it affect your instrument.

Once you confirm that the panels are up to specs, then you do the same measurement at the point when it is attached to the controller. If it have the required specification for the controller, then it *should* have current coming out from it, independent if it is PWM or MPPT.

[Blue~Go]

Just to repeat, panels can show voltage but that does not mean they are putting out amperage. This is what mine showed when they failed. Plenty of voltage; no amperage (so.... no charging input). Can you make it so only one panel is hooked up at a time? If so, do you get amperage coming in on one and not the other? What if you (gently) wiggle the wires (since it was intermittent)?

Now both panels could have faults but that is (one hopes) less likely.

I can't speak to all of HQST's products, but after I could no longer get Grape brand flexible panels (and during the time you could hardly get flexible panels at all), a friend and I both purchased HQST panels. They all died within a year or so, and that was being used carefully and with plenty of air flow. Also said friend was going to purchase some new-in-box-but-went-another-way HQST panels from an acquaintance and one was bad from the get-go (so he did not buy it). It put out volts but no amps. Granted these were not rigid panels - which are more robust - but still, such early failures makes you wonder about their quality control.

[Roly]

Chin, Thanks for the input,
I did a test weeks ago, when I was on my first controller, and measured amps going directly into an old discharged lawnmower battery brought into the coach. That was with both panels in parallel from the cables disconnected from the controller. 2-4 amps on a cloudy day. That was before the major relocation of everything. Now that the house batteries are not under the truck, it would be easier to try it directly to them, when time permits.

Blue,Thank you as well,
That is very interesting news about your HQST experience. Those guys are not easy to communicate with, and when I did the above mentioned test, I figured they'd conclude their panels were OK. The warranty is long gone now. Are Renology panels better quality, or the same thing? In view of your comments, bad panels seem much more likely than a flawed Trimetric monitor.

Thanks guys, Roly

[Scott]

I have the 100w glass/aluminum Renogy panels and they've lived a tough life, and still crank out the amps after three years of continuous use. I clean the bird poop every once in a while and that's it.

Sounds like a crusty or compromised connection of some sort. Maybe the MP4s. Or a fouled in-line fuse (assuming you have one). Good luck. Frustrating...

[Roly]

Well, I'm opting for a $200 test. Renology had panels on sale just now, and I ordered a pair the same size as the HQST's I have. The newer compact ones are nice, being about 42 x 19, but I ordered the 47 x 21 to preclude having to cut down and remount my aluminum mounts.

If they perform the same, then the panels I have are likely not at fault, unless I have bought four bad panels. I'll then replace the MP-4 connectors and make up mounts for two more panels....maybe that rationalizing the addition of a 3rd AGM.

Roly

[Blue~Go]

Will be interested to hear how it goes. You may want to test the new panels before you mount them (you can then test the existing ones too). You could consider using an extra pair of panels for ground panels. I find mine to be quite handy. One situation is that I can park in the shade and put the panels in the sun. Also the ground panels are easy to aim and tilt (whereas I might want to park in a certain way for a view or etc. - not necessarily for the aim of roof panels). That all depends on your specific usage tho.

[Roly]

Blue,

I recall your writing about the positive aspects of ground panels. I have considered how to keep the roof panels operative (if I ever get them operative) and have an additional arrangement for plugging in a length of conductor for ground panels. I think I could do so without a need to change the programming of my present controller. A marine shore power receptacle and plug and some 30 amp cable might do. I have some of these parts laying around.....I could locate it in the repurposed battery compartment, to preclude cutting a hole in the side of the coach.

I can picture a portable wireway running up to the roof, and lashing the ground panels down up there, when it may suit; maybe not when under way on the highway.. Actual sun photons are not guaranteed up here near Seattle, so four panels vice two would help.



Thanks, Roly