Any help with Trace SW4024 would be appreciated

[udygold]

Hi Forum.

I have a pretty much standard setup for off-grid.
Two TRACE inverters - SW4024, 240/120 volts, 8 kW peak, connected to 16 L16 Lead-Acid batteries configured in a 4x4 configuration with 3.2 kW solar panels.
The backup is a Generac (propane-based) 15 kW which is supposed to kick in automatically when the voltage goes below a certain level, or the demand is higher than a certain AMP level. It is a 24-volt setup.

• Batteries: The batteries are new (6 months)
• Generator: The generator cranks up and starts manually without an issue. In the past, I replaced the modume which regulated the generator output since it was pushing no more than 30 or 40 volts. The generator tech identified the problem and after $2,000 less it was putting 240v as it was supposed to.
• After that work, the system started fine - automatically or manually.

Something happened and here are the current symptoms;

• Manual start: When starting the generator manually (from the generator itself) it starts and works as long as I let it run. Side note -the inverters do not indicate that the batteries are being charged. *I do not know if it is supposed to charge the batteries while starting it manually*
• Auto start: When starting the generator from the inverter, it starts fine, and 45 seconds afterward the generator shuts down.
• The attempts to start the generator repeat 5 times (per the inverters' config) and stop

In the summer the daytime and sun are perfect for my power needs. Now, during the winter, the daytime is short and we do not have direct sun for days at the time. To be able to stay in my house I put a transfer switch and connected a gasoline generator to feed the house. This "plan B" bypasses the solar setup and feeds the house directly. This is also costly because I need to pump 8 to 10 gallons of gas every day.

Any ideas where should I start troubleshooting why the inverter sends a kill signal to the generator after 45 seconds? (If the generator starts manually it runs unlimited)

Any idea would be greatly appreciated!

 

[OzSolar]

Welcome to the forum!

Sounds like something is disconnected between the generator and the Trace's. Could be an an open breaker or loose wire.

Go to the meters menu (4) and go down until you get to Generator volts. What does it say when the generator is running?

Is the AC2 light blinking, solid or not lit at all when the generator is running?

 

[RCinFLA]

You should see green LED on inverter start to flash on AC2 input after generator starts up. This indicates the inverter sees AC input voltage. For auto start this tells the inverter that generator starting has been successful.

I believe on auto start there is a warmup delay setting that will hold off inverter attempting to sync to generator for the warmup time.

Once the inverter sync's to generator you will hear the pass-through relays click in and the green AC2 LED will turn from blinking to solid.

If the inverter remains blinking, never hear the relay click, and LED does not turn solid it means the inverter cannot achieve sync with generator.

This usually means the generator is too far out of inverter acceptance frequency range or the generator governor is unstable causing engine speed to wobble around preventing inverter from phase locking to a 'moving target'.

If inverter is unable to see generator voltage (blinking LED) or unable to sync to it, the inverter will attempt a few times then shut down generator.

I have a Generac connected to two series stacked SW4048 inverters and two series stacked SW+5548 inverters with no issues. I assume you have your inverters connected via a series stacking cable. This is necessary to keep their phase 180 degrees sync'd to produce 240vac/120vac output.

It is also preferable to have both units with the same firmware revision.

 

[MichaelK]

I have the newer version of your same inverter, the Conext SW4024. I would agree that the inverter is looking at the generator input and rejecting it as not being "qualified" to supply power to the inverter. What RCinFla said, 'This usually means the generator is too far out of inverter acceptance frequency range or the generator governor is unstable causing engine speed to wobble around preventing inverter from phase locking to a 'moving target'.

When you first start the generator and attempt to connect it to the inverter, do you hear a change in pitch of the sound of the generator? Does is sound like it is loaded up for a few seconds, and then the pitch changes again? This would be the inverter starting to accept the generator's power, then rejecting it after a few seconds as un-qualified.

One thing you might try to help things a bit is allow the generator to fully warm up first, then going into the inverter's settings and change the charging rate down to a very low level, say only 5-10% of what it supposed to be. See if the inverter is more likely to accept the generator's power if it starts out with a far lighter load.

If the "light" charging current is accepted by the inverter, attempt ratcheting up the current a few percent at a time and see what happens. After ratcheting up several times, you may hear the generator's input being dropped again. You have to determine at what point you have to keep your charging rate to make sure it works.

Taking a step back though, this is really not the root cause of your problem. The root cause is really too little solar for the size of battery you have. With four L-16 banks in parallel, assuming they are 375Ah each, then you have a total 1500Ah of storage. L-16 batteries typically want charging at a rate of 1/8th of C, so what they want to get is 1500Ah/8 = 187.5A of charging current. That's more than a single charge controller can handle.

To get that level of charging, assuming you de-rate your panel output to 85%, then what you want is (187.5A X 25Vcharging)/85% = 5515W of solar. I would recommend adding at least another 2000W of panels, along with a second controller to handle the extra current. If you have the same model as the first controller, see if they can be connected in a master/slave orientation.