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Why are my needles showing negative readings? Plugged into 20 Amp outlet, only the fridge is running along with float charging the batteries.
I need so desperately to completely rewrite that page.........busy trying to hammer out the 12kw specification document so we can get more inverters ordered...
Noise and mathematical errors will show up with small offset errors like that; it isn't harming anything.
For that matter, the revised local server implementation coming on 1.2r0 (and to the local server) puts input and output amps both on bidirectional meters that can display both positive and negative. And I need to apply those revisions to the remote server (wifi.genetrysolar.com)
I don't know if it makes much difference about hooking up the grid tied inverter but it is only rated to output 42 amps. Seems quite a bit less than one would expect at 12kw. Actually it's 10kw. Probably still more than a 6kw could handle but it is 2kw lower than 12kw.
I don't know if it makes much difference about hooking up the grid tied inverter but it is only rated to output 42 amps. Seems quite a bit less than one would expect at 12kw. Actually it's 10kw. Probably still more than a 6kw could handle but it is 2kw lower than 12kw.
It's more than the 6kw @ 12v can handle. If your 6kw was at 24/36/48v, it'd theoretically be OK with a 10-12kw blast.
The issue is instantaneous heat generation vs the thermal resistance between the actual FET junction and the heatsink pad on the case (we haven't even gotten to the heatsink the FET is mounted to). If too much heat is generated too quickly, the FET will explode as a result of this thermal resistance--even if the FET was submerged in ice water.
Now you are getting closer to the real key factors. FET's rarely die from over current. Instead they typically die from over heating and over voltage. This is one reason I mentioned proper HW design is necessary to provide robust AC coupling function.
Think further down the line too--supposing the FETs could handle the blast of power, it's ALL going to be gated into your batteries. Can they handle it for a few seconds?
Yes, inverters that work with GTI backfeed up to 2x the inverter nominal output capacity have been around for quite a while. But as you are realizing, the battery system design is another key factor. To achieve max GTI backfeed the battery system (cabling, BMS, cells) must be able to safely absorb it.
Do you have a link to a written spec sheet where this is covered?
It's all in IEEE1574 and UL1741/SA specs but they are not free so no public links. The OzInverter guys are really intrepid experimenters and they have gained much real world knowledge through many trial-and-error iterations with real loads and systems. The design is perhaps over engineered but the 6kW OzInverter has been tested to sustain 2x+ over/surge load for 20 minutes. Perhaps you can get them to be your alpha/beta testers.
Why would my inverter be flashing the power button from green to light blue? I have no errors and I'm not hooked up to the grid. Is that a wifi connection indicator?
39 minutes ago, Nilao said:Why would my inverter be flashing the power button from green to light blue? I have no errors and I'm not hooked up to the grid. Is that a wifi connection indicator?
No, the power button is not a WiFi indicator.
Are you running a grid-tie into the GS inverter's output by any chance? (That would be expected behavior for grid-tie charge 😉.)
If not, what's the OUT screen showing? (Curious if it's reading negative current.)
No, the power button is not a WiFi indicator.
Well, when I plug it in and it switches to charge mode it blinks blue, unplug it it's green. I currently have nothing but a refrigerator and fan hooked up to it and its flashing feom green to light blue. Not the true blue of grid power but a pale blue. I have never attempted to backfeed the outputs. It shows normal operation on the lcd. Nothing negative. Shows to be in inverter mode, 240 volts, 96 watts, .3 amps with power showing to be flowing out of the battery.
On OUT -> Diagnostic Info screen, what's the binary bits on the line marked "F_CHG"? (Should be 8 numbers.)
Just curious if the "charge" bitflag is getting set, but not cleared. A green/cyan flash would be grid-tie charge; it's possible that the negative amperage readings hit a threshold and the inverter thought it was getting backpowered 😉.
Not hurting anything. For that matter, a grid-tie backfeed charge is a process that the inverter really can't control--apart from "sending signals to the grid-tie inverter" or outright shutting down.
It quit doing it.
Well I talked with their tech support and they say a smaller inverter generator will be able to work in tandem with their inverter in the event of power loss.
Well I talked with their tech support and they say a smaller inverter generator will be able to work in tandem with their inverter in the event of power loss.
Makes sense, though there's a crucial difference between an "inverter generator" and an LF inverter...
I've never had an "inverter generator" apart, but I'm reasonably certain that it will use an HF-style topology inside, likely with an HVDC bus (~180-200v DC) from the generator itself (or a full HF design with a 48v bus or something from the generator itself--I have no idea!)
The critical difference is that AFAIK it's not possible to "charge the batteries" with an HF-style inverter via AC Output Backfeed. (HF inverters with charge generally have a completely separate "charge" circuit, unlike most LF inverters.)
This means that if the grid-tie output exceeds the loads, it will backfeed into the "inverter generator output"--which is unable to sink any power. Because the inverter generator is unable to sink any power, this results in the AC output voltage shooting up--which as part of the UL grid-tie regulations (and/or part of the grid-tie design) will cause the grid-tie inverter to automatically either trip off or throttle back.
Conversely, with a LF-style inverter, the push-pull full-bridge MOSFET drive will sink power...and a lot of it, very quickly. As a matter of fact (as I've mentioned above), battery charge is an uncontrollable side effect of backfeeding an LF-style inverter.
In this case, if the grid-tie inverter's output exceeds the system loads, it will similarly backfeed into the LF inverter's output--which will quickly redirect all said power back to the connected batteries. The output voltage will rise a few volts (entirely dependent on the LF inverter's system losses, i.e. transformer, FETs, wiring, etc.)--which the LF inverter CPU will see, and drop the throttle to pull the output voltage down--which pushes even more power through the system. Now the grid-tie inverter is rubbing its hands, "mmm, we can run a lot more power"...and more power comes through, the LF throttles down further...more power....until a limit is reached somewhere. (Solar input power, grid-tie maximum output limit...or blowing the LF inverter up through overcurrent.)
[EDIT: All of the above can easily happen in less than 500mS]
You might be thinking, just let the LF inverter's output voltage fly high, and the grid-tie will auto limit, right?
Not so fast. Like mentioned above, the LF inverter's output voltage increase will be very small--I would expect well under 10v (i.e. 240v to 250v, not the ~265v likely needed to trip a grid-tie). While yes, the GS LF inverters can determine that they're being backfed and INCREASE the output throttle in hopes that the grid-tie will throttle or shut down...the risk is that if the grid-tie DOESN'T throttle or shut down with the increased voltage, we have simply increased the ability for dumping yet more power through the LF inverter.
Like I've said above, my main concern with your system is that your GS inverter is configured for 12v [EDIT: And that the GTI in question is nearly double the power rating of the GS inverter]. If you were at 24v / 36v or even 48v, I would be far less concerned, as the peak charge amperage would be half to one quarter as much.
Well I talked with their tech support and they say a smaller inverter generator will be able to work in tandem with their inverter in the event of power loss.
It can work but you'll need a 240VAC inverter generator with similar power capacity as your GTI and more importantly make sure your loads are always greater than the GTI power production to avoid backfeeding the generator.