Help me understand what my SunSaver MPPT Meter is telling me

[brad1]

My solar system features two 100 watt solar panels, a SunSaver solar controller, Progressive Dynamics 4600 Converter, and a MorningStar RM-1 remote meter. I'm trying to understand the readings the remote gives me. Here is a recent read-out and what I think they mean (in consultation with the SunSaver Meter Map documentation):
Solar Input Display:
Array Voltage: 14.29v (that's what the voltage the solar array is sending to the Progressive Dynamics converter via the SunSaver controller)
Battery Displays:
a) Battery Voltage, 13.45v (the current charge of the battery array in volts)
b)Battery Amp Hours, 7095Ah (the total amps produced, stored and eventually delivered by the battery since installation)
c)Unknown reading-the meter map doc. doesn't list this one, but instead skips to item d), 1.83A (I'm guessing this is the current load reading in amps, though I would expect it to show elsewhere, according to the meter map doc.)
d)Battery Minimum Voltage, 11.15v min (looks like I drew down the battery too low on at least one occasion. I understand that 50% charge is something like 12.2 and that below that I may have damaged the batteries).
e)Battery Maximum Voltage, 15.12v
f)Battery Watts 20.39vA (I don't get this one at all)
Load Displays:
a) On
b)Load Amp Hours, .10Ah (I don't get this one too)
c)Load Current, (0.00) (this even though the refrigerator is on and when I turn on lights, it doesn't change)
Temperature Display:
a)84 (Temp at the solar panels)
b)76 (temp in the battery compartment, or possibly battery temp itself)

So what's going on here? What do these numbers tell you? What can you add to my understanding?

Thanks in advance.


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[alano]

a) no comment
b) can be reset by user
c) I'm guessing this is current from your solar array since they give you the battery power in f)
d) you can reset this. You can push batteries below 50% without damage for a reasonably short duration. Since you have a solar charger I wouldn't stress about discharging below 50% occasionally.
e) no comment
f) I'm guessing this is the power going to charge the battery. So if your battery voltage is 13.45 V, then the current is 20.39 W / 13.45 = 1.5 A.

The Load display only makes sense if you have a load directly connected to the SunSaver, such as a 12 V light. I'm guessing you don't so you should disregard this and maybe even set the load to off.

[brad1]

Additional data points for consideration: The previous data points were collected at about 3:00pm in direct sunlight. I took another set of readings at 7:00p.m. as the sun was setting. Here they are
Battery Displays:
a)Battery Voltage, 12.69V
b)Battery Amp Hours, 7100Ah
c)Undocumented display, 0.00A
d)Minimum, 11.15
e)Maximum, 15.12
f)Battery Watts, 0.00V ka

Does f) mean that the battery isn't getting any charge from the controller? And what does c) tell us?






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[alano]

So I would guess f) is like I said, the power being sent by your solar controller to the battery. Since the sun is setting the power is zero and the solar panels aren't charging your batteries. c) still looks like it's the current from your solar array feeding the solar controller.

[lsbrodsky]

By the way, if your system is stock or used the stock prewire, the solar controller feeds the battery bus, not the converter. That may be semantics, but the solar will always charge the battery, regardless of the STORE switch position, as long as there is sufficient sunlight. That controller is a basically just an ON-OFF switch so that when its setpoint is reached, the charging is stopped. It is really not a multi-stage charger and can be easily replaced.
Larry

[AirRiggie]

It looks like your panels are not producing enough voltage to keep a good and constant charge....since you are using an MPPT controller, it would be better if you wire the panels in series. By yur description, it sounds like your 2 panels are wired in parallel. If you wire it in series, you will double your output voltage and your MPPT controller will automatically convert the excess voltage into usable amps. Search youtube for this explanation..."PWM vs MPPT charge controller". Hope this help.

www.youtube.com/watch?v=wmyuxKmlBCk

[alano]

Originally Posted by AirRiggie

It looks like your panels are not producing enough voltage to keep a good and constant charge....since you are using an MPPT controller, it would be better if you wire the panels in series. By yur description, it sounds like your 2 panels are wired in parallel. If you wire it in series, you will double your output voltage and your MPPT controller will automatically convert the excess voltage into usable amps. Search youtube for this explanation..."PWM vs MPPT charge controller". Hope this help.

I disagree. Brad's panels are not producing any power because it's 7 PM. From all indications his system is working fine.

I would also disagree with you that it would be better to wire the panels in series. While it's true that MPPT controllers can accept higher input voltages, in Brad's case there won't be any practical benefit to wiring the panels in series. An MPPT incorporates a buck/boost DC/DC converter that will take whatever power is available from the solar array and convert it to the optimal battery voltage his batteries require for charging. Wiring the panels in series will double the voltage and half the current but will result in the same power. The topic stirs quite a bit of emotion and I frequently argue for series panels in order to preserve the pre-wiring and enable a more friendly DIY install. The downside to series panels can be loss of performance with partial sun cover. This is somewhat mitigated by the addition of integral bypass diodes, but that's a topic for another day. Bottom line, Brad won't see any practical benefit to configuring his panels in series.

[AirRiggie]

Ah, but remember, no voltage no current. Voltage is the FORCE ( hence E for electromotive force) that dictates how much current it can actually push, the higher the voltage the more current it can push...if the panel ( even if its rated at 100watts) is not producing enough voltage, there is no energy for the MPPT to convert ! O volts X 10 million Amps is still 0 watts ! So even if you have 20 panels in parallel if you have a total voltage production of less than what your battery voltage is...you got squat for charging capacity, MPPT or not. The MPPT charger CAN NOT convert energy that is not there to begin with. No harm in experimenting and see what works best for Brad's situation. BUT to REPEAT the same procedure that you already know failed a few times is nothing more than setting yourself for the same failure.

[alano]

If the total voltage from the solar array is less than required for the battery, the MPPT charger will boost the voltage. One of the reasons why MPPT chargers cost more than PWM systems is the additional sophistication to perform these tricks. This type of DC/DC converter is called a Buck/boost converter and is quite common.

[AirRiggie]

quite easy to make a simple circuit to switch from a parallel configuration to a series configuration with the flick of a DPDT switch..WIN WIN, best of both world ...Parallel when the SUN is really bright, Series when the its Dusk or Dawn

[brad1]

I love this place. Every time I ask a question I get answers that help me figure out my issues. For this one, once I boiled down all the input, the answer was pretty simple. Thanks for helping me get there.

BTW, I talked to Sunsaver, the guys who made the MPPT processor, and they were super in helping me understand my data, and the Airform's input. What I wanted, of course, was a simple, uncomplicated explanation and a no-cost fix for the problem I couldn't even diagnose and, it turned out, didn't even exist. Sadly, in the real world, none of tha happens. And so it was and is,

Again, thanks all.