Vfxr3524 grid zero

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Vfxr3524 grid zero

Post by Foxmxrcer » Tue Sep 10, 2019 5:31 pm

I'm relatively new to the whole solar thing, but I do have a decent understand 6 if both AC and DC electronics. I recently bought a house that was running on nothing but solar, with the vfxr3524, midnite classic 150, and mate3. The seller claimed everything was ready and good to be grid interactive if desired. So, me wanting an electric water heater, wanted grid interactive. After the pet company hooked the line back up from the pole, I got into the mate3 and changed the settings to grid zero, set the parameters, shut the breakers off, turned the grid breaker on, and then the solar breaker (in the main box), and it blew immediately. What gives? My only confusion is that the solar feed in the main panel, is a double pole 30a breaker, with the hot from the inverter running to one pole, and a jumper jumping to the other. That doesn't seem right to me, but I'm not sure?

Any hello is greatly appreciated!

Thank you,

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Re: Vfxr3524 grid zero

Post by Mike Curran » Thu Sep 12, 2019 4:50 pm

Can you post a photo of your wiring or a wiring diagram? I'm having trouble visualizing what you're describing...

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Re: Vfxr3524 grid zero

Post by sparksalot » Fri Sep 13, 2019 8:00 am

Yes, wiring diagram please.

Without diagram and reading above I see a major issue:

Jumper between DP L1 & L2 are there for only having 120 VAC inverter which can only feed 1 of the 2 panel bus.
So Jumper is required to be installed to feed the unfed second bus since lacking 240 VAC power source from any second inverter.

For a 240 VAC (2 panel bus) distribution panel and lacking 240 VAC supply there would be only every other breaker work without adding the L1 to L2 jumper.
Then when later adding the POCO 240 VAC and still while 120 VAC bus jumpers are not removed causes a dead short circuit between the newly added POCO L1 & L2.

Sorry, but you don't understand much electricity and are a danger to yourself and others near to you.

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Re: Vfxr3524 grid zero

Post by jnh » Tue Sep 17, 2019 9:20 pm

The best way to set this up is to have two separate breaker panels. Keep the current one fed from your inverter, and with the jumper between L1 & L2 as-is, but DON'T connect the utility service entrance there! Instead, the utility should come into its own breaker box. One of the outdoor variety designed to mount below or next to the meter may be the simplest retrofit. Place breakers in this box to supply your water heater, and any other loads that need 240V, more power than the inverter can supply, or which you wouldn't want to run from batteries during a blackout.

Unless you want to keep your two power systems completely separate, the utility panel should also have a single-pole breaker supplying the inverter's AC-In terminals. With this connected, an internal transfer switch within the Outback inverter in Grid Zero mode will automatically send utility power through to your other panel as needed, merging it with locally-generated power. If and when you decide to get approved for net-metering, the AC-In wiring can optionally be used to "sell" excess solar power back to the utility as well (yes, it'll push power back out on the "In" circuit), but in a controlled way.

The inverter's AC-out terminal should NEVER connect directly to your utility feed - only AC-IN should. You're probably lucky that jumper across the two hot legs (which became a dead-short when supplied with 240V) tripped the breaker immediately, averting a dangerous situation that could have hurt someone (backfeeding lines during an outage), or more likely just damaged your inverter or other equipment.

The 30A breaker supplying your existing panel won't let you take full advantage of the utility pass-through function, though - that inverter's transfer relay can pass through 60A, and even when operating standalone, its surge rating is well above 30A. So, you may want to up-size that wiring run. I use 6 gauge to both AC-IN (utility service entrance panel to inverter) and AC-OUT (inverter to subpanel), with a 50A breaker at both ends of each. Don't just put in a larger breaker without ensuring the wiring can safely handle that amperage, of course - e.g. 10ga is good for no more than 30A.

It's important the Neutral and Ground be bonded together in only one of the two panels - typically the service-entrance one, meaning you might need to remove an existing bond in the panel you have now. All grounds should be bonded together as well, preferably outside the house (with solid 6ga or thicker copper, avoiding sharp bends) so as not to give lightning another pathway in.

If you're not fully comfortable with all of this, consider hiring a local electrician.

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