How much PV input voltage is needed to start AC on inverter (Deye 8K)

[kolek]

Running DEYE inverter (SUN-8K-SG01LP1-US) no grid connection, no battery, 1 strand of 7 x 455 watt solar panels in series.
Was cloudy today, PV input voltage according to the inverter was about 340V @ 0.1 amps during the day.
So that's 34 watts, apparently not enough to kickstart the inverter.

3 questions:

1. Is it normal for this many large solar panels to only generate 34 watts output on a cloudy day, or does it sound like I've done something wrong?

2. Normally for these "all-in-one" inverters running with grid or battery, what is the minimum PV voltage and/or watts required from the solar panels to get the inverter to "wake up" and start making AC?

3. The datasheet for this inverter says "Start-up Voltage (V) = 125"
https://www.deyeinverter.com/deyeinverter/2023/11/22/datasheet_sun-5-8kk-sg01lp1-us_231121_en.pdf
What is "starting up" with 125V? It means I can charge start charging a battery (when I get one) if the PV input is > 125V? It means the LED panel on the inverter will "wake up" with 120V PV input? It means it should be able to start making AC with 125V PV input?

 

[schmism]

I dont think you'll have much luck doing what you want to do with no battery.

WIll has tested this several times as well as other reports that the inverters just dont take large transient loads well on solar alone.

I think 150v is the actual min voltage required to do real work.

With no battery you have no way to regulate transient loads on the system and or transient sun. (cloud passes over)

 

[sunshine_eggo]

1) clouds suck. 34W sounds low, but it might be normal.

2) When on grid or battery, they are already awake and making AC unless an energy saving mode is enabled. If that is enabled, a certain size load must be present to start inverting.

3) The PV voltage must be at least 125V to start the MPPT.

Not sure what you're trying to do, but I suspect you are going to be very disappointed.

If you're trying to get AC power purely from PV, that may be very difficult. The MPPT must pull exactly the power needed to power the load - no more and no less. If the load changes, it can't adjust to the new load instantly.

At best you will get erratic and unreliable performance. These things need either grid or battery to act as a reservoir to smooth out the loads and give the MPPT time to adjust.

 

[Batronca]

Any “load” to inverter?

 

[kolek]

Thanks to everyone responding.
I have a 28kwh battery and a grid connection I can use, I just having gotten around to assembling the battery and connecting the inverter to grid. At this point I'm just curious to see if the inverter will come on and power anything with a single strand of panels. (My final configuration will have 4 strands).

 

[sunshine_eggo]

Thanks to everyone responding.
I have a 28kwh battery and a grid connection I can use, I just having gotten around to assembling the battery and connecting the inverter to grid. At this point I'm just curious to see if the inverter will come on and power anything with a single strand of panels. (My final configuration will have 4 strands).

Since this is just a test, I would attempt only resistive loads like a space heater or incandescent/halogen lights.

 

[RCinFLA]

PV voltage will rise to Voc level with no external load on PV array when illumination generated current exceeds the PV array leakage current,

At this point, PV array will have near Voc voltage but will support zero additional external loading. If you try to add addition external loading the PV array voltage will immediately collapse to near zero voltage.

You need enough illumination level on PV array to support minimum charge controller current required. This varies from AIO to AIO. Most AIO's use battery power but some units like SolArk allow to run without batteries, although I would not recommend doing it as it is too unreliable.

On a SolArk, you can figure needing a minimum PV power output necessary to supply all the idle power of the unit, if trying to run without batteries.

 

[dhall1793]

Haven’t read through all the comments but I think the specs are just a product of the internal components. I think the inverter circuit has a minimum of 125V but the MPPT has a minimum input of 150, thus the inverter doesn’t do anything until 150V. Not positive just what makes sense to me.

What is the Voc and Isc of each of your panels? The .1 amps of current doesn’t sound right.

 

[LydMekk]

All the above plus: are you sure the panel string is connected in SERIES and not parallel?
With parallel you will never reach the minimum voltage.