question

logart avatar image

MPPT 150/60 Low Wattage and Amps- Always Bulk Mode

Hello Everyone,

I have been having an issue since day #1 with my system:

  • 1 x 210w 24v Solar Panel (Voc 39.66V, Imp 6.24A)
  • 1 MPPT 150/60TR
  • 2 x Battleborn 12v 100ah in series (24v)
  • 1 x 600W Power Inverter

When in full-sun, I am seeing ~0.4A, ~31V, ~15W for "solar" on the victron app dashboard and I have never seen a mode other than "Bulk" mode in over a week that I have been running. When I measure the V and A at the PV wires coming into the controller I am seeing ~5A, ~38V.

At first I thought maybe my batteries were not charged fully so I charged them individually with my NOCO 10A charger. Then someone said maybe you have no load, so I connected my load and nothing changed and my batteries tripped their low voltage protection after a number of hours.

I am still seeing minimal charging no matter what happens.

Any ideas on what I can do to start troubleshooting this issue?

mppt smart solar
6 comments
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Make some screenshots of the App (main screen, history, settings).
logart avatar image logart Matthias Lange - DE ♦ ·

Here is an example of a typical status mid-day:



logart avatar image logart Matthias Lange - DE ♦ ·

From this morning:


logart avatar image logart Matthias Lange - DE ♦ ·

This morning:


logart avatar image logart Matthias Lange - DE ♦ ·

Settings


Update: got my second panel connected. W/V doubled, A still at 0.5



2 Answers
Paul B avatar image
Paul B answered ·

Check the array connections as I suspect you have a bad connection there at a join and thus no real power is getting the the MPPT. a array wiring diagram would help

as I dont know the array setup o/c voltage its hard to sugest a test. but if the O/C voltage is say 120 then try below

one way is to say get a 120v incandescent bulb say 100 (pus watts) unit and connect it to the arrays output (remove the arrays two wires from the MPPT unit and place them onto the bulb - the bulb should light it

get the write voltage bulb thats suits the open circuit voltage - your picture show it as about 40 volts. so get a bulb thats above that voltage.

Then measure the amps using a DC amp clamp meter.


Basically you need to put a high DC load on the arrays output connection and see if it meets the arrays specs

anyway lots of different ways to test


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I have tested both the V, and A coming into the controller and they are both within the normal values expected. I have had the batteries both discharged, and charged with no difference.

Here is basically what my setup looks like.

myhomebuzz avatar image
myhomebuzz answered ·

Hi @logart

Also look to disconnect or decrease the demand on your 600W converter. 600W at 24V equivalent to 25A.

If the 25A or other A are in use, your output is only 6A (cables, connections, sunshine, position ...) with a maximum output of around 19.3A with your panel. Do not forget that this small world also consumes energy.

So there is more discharge than charge and the Bulk mode will always be present to recharge your batteries which are continuously draining.

Indeed, you must check your cables and connections. Please also position your panel in direct sunlight.

In addition, in your request you have 1 panel, while in your sketch, there are 2 panels.

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I have only tried a load on my inverter one day. I have my inverter off since then, still no charging. My panel is mounted on a pole mount in full-sun. I only have a single panel right now because they messed up my shipment (twice!). I am trying to determine if I have something configured wrong, or if adding the second panel will fix all this. I read in the manual something about 60 cell panels in a 24v system requiring 2 panels but I don't know if that is an "optimal" configuration or a "mandatory" configuration.


Good.

Just a few more questions:

Dimensions in mm2 of PV cables to MPPT:

Cable length (distance in m) between PV and MPPT:

Dimensions in mm2 of the MPPT cables to the batteries:

Cable length (distance in m) between MPPT and batteries:

Altitude in m:

Cable composition (Copper or Aluminum):

logart avatar image logart myhomebuzz ·
The PV cable is 8awg (which I think is 8.3mm2?) @ 100', controller to battery cable is 4awg (21.15mm2) @ 2 ft, copper. altitude is 821m

Distance of 100 feet between PV and MPPT?

logart avatar image logart myhomebuzz ·

Yes, the panels are in my back yard, my MPPT is on my garage so I have 8awg PV wires. I was able to see ~5A coming into the MPPT.

OK

To keep it simple and not to go into technical details, the energy transport depends on the cable. For 100 feet (31 m) and permissible transport by reducing energy loss, the cable should be 16 mm2 (5AWG).

To understand, if you want to quickly empty a bathtub of its water, the hose must be wide. If it is too narrow, the water will flow slowly at a low rate.

I think your cables are too narrow.

The calculation (reminder) to be taken into account for the cable section is: S (section) = p (resistivity) * 2 * L (meter) * A (intensity) / ∆U (voltage drop * Volt). In your case: S = 0.017 * 2 * 31m * 6.24A / 0.48V = 13.7 mm2 => 16 mm2 = 5 AWG. I did not take into account the loss due to the Joule effect, but it is very telling.

logart avatar image logart myhomebuzz ·
If I were dealing with a voltage loss would I still be seeing 5A+ and 39V+ going into my controller? Once I get my second panel installed in-series my voltage would effectively double.