Need help with solar performance

[jonyjoe101]

The voltage readings never go above 14 volts. When in bulk or absorption you need to be closer to 14.4 volts. Your system is not producing max power.

Putting you panels in series will double your amps that your getting. With 600ah of battery you need every amp you can get.

In this thread someone had a similar problem from his 2x 100 watt panels, he had them in parallel, and saw an improvement by connecting them in series
https://vanlivingforum.com/threads/i...-panels.41071/

[1der]

While you are correct that in-series panel connections will double his line-in voltage (not amps) and reduce voltage drop (line loss) from the panels to the SC, it will be highly detrimental with his shading problem present on the rear panel.

Series connection could only increase efficiency by reducing the line loss and have some small savings realized from the higher voltage. That is not going to be a doubling of amps getting to the SC. The SC is already receiving over 20 volts.

Let's establish what is going on here first before a change.

We still have not established for certain that the panels are in parallel or series, although preliminary voltage readings indicate parallel. Once the data is validated in completely unshaded light we will have a better idea. And if a clamp meter is introduced we can get a better read on current.

At some point it may be necessary to get to the connections under the panels. This could be a connection problem on the roof side wiring.

[FormerBluffer]

I checked the solar output again today. There was a little hazy smoke in the sky so the sun wasn’t as bright as yesterday. Also, it was slightly earlier in the day (started about 1:00) so the sun was a little higher in the sky. I did make sure this time that there was no shade on the panels.

I checked the same as I did yesterday (first with a “normal” load of ~6A and then a second time with a higher load (added microwave).




I don’t understand what changed that could be responsible for the different results. This inconsistency has been my experience. I’ll have a long string of days with little charging and then a day comes where the charging seems great even though there isn’t much change in the intensity of the sun.

Out of curiosity, I then repeated the tests on each panel separately by covering one panel at a time. I thought this would be a way of seeing what happens if an entire panel was in the shade. I was also curious whether there were any differences in the panels.



As you can see, the results were very similar for each panel. This leads me to believe that we can’t assume that yesterday’s lack of charging was due to the front panel being partially in the shade.

Today’s results were much better than yesterday and showed that I was getting good charging regardless of the power load.

Here are some thoughts that I had but, unfortunately, they aren’t giving me any hints at a solution:
· Based on my Voltmeter readings taken from the solar panel terminals on the solar controller, PV was lower today (17.49V and 16.65V) vs (22.08V and 20.21V) yesterday. Does this have any significance?
· Battery voltage was higher today (13.7V and 13.39V) vs (13.15V and 12.91V) yesterday.
· Shouldn’t the lower voltage yesterday be more likely to cause the Solar Controller to go into Bulk mode?
· Today, I was actually getting amps in/out under both “normal” and “high” loads. Yesterday, I didn’t get anything under “normal” load. Why does a heavy load affect amps in/out from the solar panels?
· Today the Aux Out light was off and the Aux Volt was at 0.0, while yesterday the light was on and the Aux Volt readings were 13.1 and 12.9. It seems to me that this merely confirms what we are seeing elsewhere. Since the default setting for Aux Out (out) is ch9 which the Blue Sky manual says is for Auxiliary Bat Charge, today was O.O and the Aux Out light was off because all available solar power was being used to charge the batteries and nothing was available for an Auxiliary Battery (which I don’t have hooked up). Conversely, yesterday, no solar power was going to the batteries so all of it was available for an Auxiliary Battery. Unfortunately, this doesn’t explain why.

Next, I was going to try to look through the various Solar Controller settings to see how they match up with my readings. For instance, since my FLt setting is 13.2, why didn’t the Solar Charger go into Bulk Mode yesterday when the Battery Volt readings were below 13.2V, yet it did go into Bulk Mode today even though the Battery Volt readings were above 13.2V? Please let me know if you think this makes sense.

Any thoughts or suggestions you have are greatly appreciated.

Thanks

[Scalf77]

I apologize for my delay, but I am traveling. I will try and download the manual so I can be on the same terms with you.

If you are comfortable with your criteria, then you need to move to the other variables, Starting SOC, and consumption. Consumption is probably being covered by your criteria.

With the external panel port, I would suspect that your system was set up as parallel. It much harder to pull that off correctly in series.
to
As far as SOC, I would try to look and draw anything between SOC and your pour performance.

It could really be that you harvest more solar power because you have more needs. While the performance may better, it might not be good enough to fully charge the battery. This results in the next day you your needs are lower (if that makes sense).

Possibly on the sunny days you complete to a full charge (although you haven't mentioned voltage that makes me think so). In any event, the next day of good sun may show a poor harvest, because the needs are lower.

[boywonder]

Originally Posted by FormerBluffer

Why does a heavy load affect amps in/out from the solar panels?

...Because the heavy load drops the battery voltage below the float voltage and starts the charging cycle again in bulk mode where the charger gives the batteries lots of current.

"heavy load" is microwave running...that should be pulling at least 100A from the batteries.......6A is a light load for lithiums.

..that being said...it appears that the controller was not in bulk mode today under heavy load based on your tables above......which is a little odd.

Other than that, it appears that your system is working normally. 13A x 14 V=182 watts....about what I'd expect out of a 230W array is good sunlight.

And your blanket test shows that each panel can output over 6A..as expected.

[FormerBluffer]

Originally Posted by boywonder

..

..that being said...it appears that the controller was not in bulk mode today based on your tables above......which is a little odd.

Sorry, my charts are wrong/misleading on this. I shouldn't have included a separate line showing a separate light for Bulk charging. Instead the way the Controller indicator lights are set up is that, if both the Float and Absorption lights are on, it means that the Controller is in Bulk Mode (there is no Bulk mode light). When I was putting the chart together I was just copying off the display, but failed to change it when I realized the mistake. So today, we were in Bulk Mode, but yesterday we were not.


Sorry about the confusion.

[jonyjoe101]

The amps output looks good. Your panels and controller are capable of producing max amps (13 amps).

But your voltage is low, you have to raise the bulk setting higher to compensate for voltage drop.

The bigger the difference between the controller voltage and the battery voltage the more amps your battery will receive.

Example if the bulk setting is 14.4 volts and your battery voltage is 13.1 volts the battery might get 7 amps, raising bulk setting to 14.6 amps you might get 8 amps, and if you have very bad voltage drop raise even higher to get the full 13 amps your panels can produce.

Next time you have full sunlight write down the voltage reading from the controller LED, then use a multimeter to read the voltage off of the battery terminals. The difference from the 2 is what the voltage drop is.

Right now your batteries aren't getting fully charged since the voltage is never climbing above 14 volts. Its not a big deal for lifepo4 which don't require to be charged to 100 percent every day. But eventually it will drain the batteries to zero percent, and 600ah of batteries will take weeks to recharge with 230 watts of solar. That's why I keep my batteries at 100 percent everyday.

[boywonder]

Originally Posted by jonyjoe101

Example if the bulk setting is 14.4 volts and your battery voltage is 13.1 volts the battery might get 7 amps, raising bulk setting to 14.6 amps you might get 8 amps, and if you have very bad voltage drop raise even higher to get the full 13 amps your panels can produce.

Tread lightly here...... the max voltage for LiFePo4 cells is 3.65V. 14.6/4=3.65V per cell. This may trigger nuisance trips of the battery BMS to protect the battery which can be a PITA at best.

..also keep in mind that the voltage drop due to wire resistance may be relatively large at higher currents, but will head to zero when the battery gets close to fully charged since the current will drop a lot, putting 14.6V on the battery when the current approaches zero before going to absorption mode.

[1der]

FB- Do your ReLion batteries have visibility via bluetooth as to the voltage of individual cells?

Do you keep your rig connected to shorepower?

[FormerBluffer]

Originally Posted by 1der

FB- Do your ReLion batteries have visibility via bluetooth as to the voltage of individual cells?

Do you keep your rig connected to shorepower?

I don't have bluetooth visibility for the batteries.

I have never plugged it into shore power when using the van. When I am regularly using it, I plug it into shorepower between trips because I keep the refrigerator running and it's the big power draw. However, if I don't expect to use the van for a while and turn off the refrigerator, I don't plug in unless the battery level starts to get low.


As I was looking at my notes, I realized that I forgot to mention something that I thought was interesting. On the first day that I ran my tests (the day when I had some solar charging under "high load" but nothing under "normal load"), the SOC was around 38% and the battery voltage reading for “normal load” was13.15V. Whereas, on the 2nd day (the day when I had good solar charging in all situations), the SOC was around 78% and the battery voltage reading for “normal” load was 13.37V. Shouldn't the lower SOC and battery voltage numbers indicate a greater likelihood that Bulk Mode charging will be triggered?