Where did the amps go? A LD solar "adventure"

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November 09, 2022, 12:22:19 pm

The failure of our solar installation on the LD and the resulting tasks to figure out what went wrong may be of interest to some future readers, so here goes.

A note at the start: nothing I say in this write-up is implied or direct criticism of AM Solar or their product lines. We are satisfied customers of AM Solar and their product lines provided the solution to our problem.

Our original system was installed on our IB-30 by AM Solar on 7-23-2014. It consisted of four Grape 135w PV panels (tiltable), a Blue Sky 3024i charge controller with the remote monitor/control panel and the existing Trojan T145 batteries. This system has performed flawlessly until January 2022 at the Lazy Daze gathering in Quartzsite with the panels tilted, we noticed our charge controller was reporting only 2 to 3 amps output during pre and post solar noon. Around solar noon, we were only seeing high 4 to low 5 amp output. During the day, we were struggling to return to full floating charge on the batteries and on most days we only got back to 97% in bulk charge stage. Not good.

At Quartzsite, with the help of Steve, we checked the PV panels for damage (none observed) and we opened the combiner box to inspect. Inside the combiner box we found that no dielectric grease had been used on the panel and output connections to the bus bars. There was some corrosion. We cleaned connections and noticed no change in the diminished current. We also tried individual panel voltage measurements but they were inconclusive because of the difficulty in testing the panels in situ (clouds, sun angle…). Our batteries were in need of replacement so I replaced the flooded cell Trojans with new AGM batteries. I really didn’t think that was the problem but it was a place to start. As expected, no change.

Head scratching time – three variables remain: wiring, charge controller or solar panels. We discounted the panels and wiring to start as they seemed least likely to fail. The charge controller became the focus of attention. It’s performance seemed nominal but it was possible that it was bad. We had a previous event the year before in which we had touched the remote control panel without discharging fingers and the resulting static jolt had addled the controller’s brains necessitating a complete reset/reboot. The controller came back online at that time, seemingly without problems, but, now it was suspect. I rebooted the charge controller again and reset all the parameters for AGM batteries with no change. I checked the charge controller’s temperature sensor and it was accurately reporting the temperature of the batteries. I also looked at the shunt current and it was nominal, but out of an abundance of caution, I reset the shunt. None of these steps caused any change.

The wiring was all carefully inspected at all connection points and with the exception of the combiner box, all connections were tight and clean.

Now we are down to PV panels or controller. I opted to replace the Blue Sky 3024i with a new unit. Properly installed and programmed, there was no change in the anemic output amps. Well dang.

Roll the calendar forward to October. (Yes, 9 months after Quartzsite, but life is what happens when you are making other plans.)

With the help of my son, I was able to remove all of the Grape 135w PV panels from the roof of the LD and conduct some accurate bench testing. The panels are rated by Grape at 21.3 volts open circuit and 8.34 amps short circuit.

The panels were cleaned and closely inspected for damage. Nothing obvious was observed.

All of the blocking diodes were removed and individually tested. It was here that I was expecting to find the problem, but all of the diodes tested as working.

At solar noon in Phoenix with clear sky, the panel voltage open circuit measurements were 19.4, 19.55, 19.95, and 20.52v. Those voltages are within expectation.

BUT, the measurement of the short circuit amps tell the story: 2.05, 1.95, 2.12, 2.04 amps. All of the panels had gone soft. I was amazed. For all four panels to fade at the same time is, in my opinion, probably a defect in the PV cell manufacturing process, which is in China. No offense intended, it was 2014 technology.

I consulted with AM Solar and they agreed with my diagnosis. I asked them for their replacement recommendations and we now have three 200w Rich solar panels on the roof of the LD. All PV panels, associated wiring and the combiner box have now been replaced and the system is back to performing as expected.

The takeaway: AM Solar is, in my opinion, the premier RV solar company in the western US. At the time we had them install our system in July 2014, they were using Grape PV panels which are distributed locally in Eugene, OR. With the passage of time we have discovered that the PV component of the panels was not robust enough to survive an expected 20 to 25 years of service. This isn’t a criticism of Grape because they were doing the best they could with existing technology in 2014. As to warranty, Grape offered a 5-year defect warranty on the panels. We are way outside that time. We also learned that Grape does not manufacture the same size panel, nor could we find anyone else with our original panel dimensions.

You just can’t find reliable data on the life expectancy of PV cells. Anecdotally, there are estimates of .1 to .5% degradation per year but all of these estimates seem to be based on algorithms rather than hard testing data. And that seems reasonable because how can you test a PV system in real time for a 20-to-25 year span? Not possible. Again, my opinion – I suspect that as we move forward over the next few years we will hear more stories about PV panels that have failed in time frames that are stunningly short of expected life span of these panels. Panels made for and marketed to the RV community may have construction standards that don’t rise to those of commercial installations, like on business and residential properties.

And here is another gem. We have tried to find a recycling option for the old panels. You guessed it. No one is doing it. We turned to the City of Phoenix looking at hazardous waste disposal. They warn against discarding PV panels in the general refuse system. It’s illegal to do so, but they don’t have any recycling program. Locally, there is no private company accepting PV panels for recycle. The solution of one problem generates unexpected consequences.

There you have it – our Lazy Daze solar adventure. I’m not seeking advice or criticism. I’ve been there, done that as you can see how this all unfolds. Hind sight is always 20-20. It is my hope that this “camp fire story” may help someone else in the future who is scratching their head and wondering why the amps have evaporated.

Dan and Lynn