Voltage across 4 100w panels in parallel reads 22.4v, but the MPPT only reads 12.5v and won't charge (despite showing the "sun" icon)

[JBMakes]

Here's the setup:

4 100w renogy 12v panels in parallel
100ah Renogy LiFePo Smart
RVR40a MPPT
700w pure sine inverter (in parallel with the RVR40)
(all of these were purchased within the past month

Here's the issue:

When I measure the PV leads outside the RVR40, I read 22.4v, but as soon as I install them I only read 11-12v across the PV terminals. My battery is at 80% soc, all the parameters are set correctly, all the contacts are good, and this happens whether or not the system is under load or the battery is below/above 50% soc. Because the voltage across the PV terminals is so low, the system won't charge.

Anyone know what could be causing this?

 

[Mattb4]

The most often reason is a bad connection from the solar panels. Enough resistance that under any load the voltage you read goes away.

 

[JBMakes]

The most often reason is a bad connection from the solar panels. Enough resistance that under any load the voltage you read goes away.

So I've tested all the connections between the panels and the MPPT and they all seem fine, and the voltage drops only across the terminals once the PV cables are installed. Could this still be the issue?

 

[Mattb4]

With all your panels in parallel it would be unlikely that a bad panel was dragging down the others. So if it is not a connection issue (and I assume you are hooking everything up correctly) the only other possibility is the SCC is shorting out PV pos and neg instead of properly transferring the power to charging.

If you post an image of your SCC with wires connected it might help.

 

[Suijkerbuijk]

Look in your mppt if the clamps are Dirty. (You never know if its a return one )
Are the cable to your mppt with or without a ferrules.
And are the ferrules a good connection on the wire or mmpt .

This the only thing i can think of .
Wel the connection on the cable from the pv it self are not good .

 

[efficientPV]

Does your charge controller show any current.

 

[JBertok]

If the MPPT is functioning properly it would work with just one panel connected. The maximum power point for one of those panels is 20.4V according to spec, so that's about the voltage you should be seeing with a clear sky.
In terms of cabling, there must be something that you're using to parallel the panels. Testing with just one panel provides the opportunity to eliminate those from the circuit. I don't think those panels have blocking diodes, so one shaded, even partially, in a parallel setup isn't good either.

 

[mikefitz]

With 3 Renogy products you have a higher possibility of something not working correctly.
Disconnect everything.
First check the battery will receive and deliver charge, use a different charger or power supply to establish that charging take place.
It's possible the battery is protection mode.
Test the panels for short current value, use a DC clamp meter. If this is not available, connect to a 24 volt vehicle bulb or two 12v in series. This will establish the panels are delivering current. A further test is to connect the panels directly to a battery and monitor battery volts and current or a period. Don't leave connected.
If the battery and panels prove to be OK it's the controller that may be faulty.
Connect the proven battery, or any 12v working battery, perhaps out of your vehicle, to the controller , then connect the tested panels.
If still no charging taking place its a faulty controller.

 

[ThaiTaffy]

I'm confused 12v panels in parallel will only output 12v even if you have 100 of them, the 20 or so volts your getting is voc most SSC need 5v above battery voltage to work so go 2s2p up the voltage to 24v half the amps and enjoy.

 

[Mattb4]

I'm confused 12v panels in parallel will only output 12v even if you have 100 of them, the 20 or so volts your getting is voc most SSC need 5v above battery voltage to work so go 2s2p up the voltage to 24v half the amps and enjoy.

Typical panels rated for 12vDC charging output a Vmp of 15-19vDC and a Voc of 20-24vDC. He did not state battery voltage but from context it is assumed to be 12vDC (it would be fairly strange if the OP thought 22vDC could charge a 24vDC battery). Indeed his reading of the panels voltage is 22.4v right in line with what you would expect.

Once connected to the SCC that PV voltage drops to 11-12vDC, which is likely battery voltage, thus no charging can happen. This voltage amount does draw into question actual battery capacity remaining because you would expect a bit higher if they were 80% or 50% as he noted. However it indicates that the panels are not being able to provide any charge voltage. Which if he ever gets back to us further investigation might reveal the cause.

 

[Suijkerbuijk]

I use 100 watt renogy panels.
And i have easy 20.8 volt and higher .
Its now 20:00 here and the battery is over 90% so it charge slow .

 

[ThaiTaffy]

Typical panels rated for 12vDC charging output a Vmp of 15-19vDC and a Voc of 20-24vDC. He did not state battery voltage but from context it is assumed to be 12vDC (it would be fairly strange if the OP thought 22vDC could charge a 24vDC battery). Indeed his reading of the panels voltage is 22.4v right in line with what you would expect.

Once connected to the SCC that PV voltage drops to 11-12vDC, which is likely battery voltage, thus no charging can happen. This voltage amount does draw into question actual battery capacity remaining because you would expect a bit higher if they were 80% or 50% as he noted. However it indicates that the panels are not being able to provide any charge voltage. Which if he ever gets back to us further investigation might reveal the cause.

Sorry not familiar with renogy panels when he stated they were 12v I thought 12v, now looking at the spec sheet is can see they are 20v

 

[zanydroid]

Sorry not familiar with renogy panels when he stated they were 12v I thought 12v, now looking at the spec sheet is can see they are 20v

12V panels generally mean “for charging 12v batteries, including with PWM”. They don’t mean anything about electrical specs. Same with 24V

It’s kind of a dumb convention.

 

[Suijkerbuijk]

Sorry not familiar with renogy panels when he stated they were 12v I thought 12v, now looking at the spec sheet is can see they are 20v

Well
Its sell for 12 volt systeem .
So it can only do 22volt on the panel.
If you have a 24 volt systeem u use 2 of them seriële.
Or you go for a singel panel for 24 volt that have 36/40 volt output from the panel.

Its sell this way really by store's

Call it a 12 volt pack deal.

 

[JBertok]

You'll see the term "nominal" used in reference to equipment specifications. A 12V nominal panel has a maximum rated power output at a higher voltage, like 20V for example, but such a panel would alone be inadequate for a 24V system for example.
A Lithium Iron Phosphate battery marketed as "48V Nominal" is actually 51.2V.

It's not likely you'll find many fans of Renogy on this forum, or any forum really, but work through the issue by reducing the number of components to the bare minimum to get a functionally complete circuit, and validate the charger as the first step in trouble-shooting.

 

[Rider]

It's possible you're not meeting the minimum voltage threshold for charging to start, which is typically +5V over the nominal. I didn't look at the specs of any of your devices, so not sure what the voltage limits are.

In simple terms, a 12v panel connected to a charger connected to a 12v battery will not charge, because you need 12V plus 5V from the panel to get the charger to start. Not the VOC voltage, the loaded voltage, which you say is between 11 and 12V.

Two panels in series makes 24 volts, but the charger can still connect to a 12V battery. Now you have enough voltage at the charger to begin charging.

I'd parallel two panels, parallel two more panels, then series the two sets of parallel panels to raise the voltage well above minimum, as long as it doesn't exceed the input limit of the charger. Same total watts, just higher voltage, lower amps.