What the differnce between PV Input Voltage and PV Array MPPT Voltage Range

[drakejest]

I have a deye inverter, in its manual there is something i find confusing

PV Input Voltage: 370 (125V- 500V)
PV Array MPPT Voltage Range: 150 - 425V
No. of MPPT Trackers3
No. of Strings MPP Tracker: 2+2+2

Whats the difference between PV Input Voltage and PV Array MPPT Voltage Range? In my about to be set UP i have 3 strings, each strings will be connected to an MPPT. But my concern comes is in one of the strings i really want to have a 9 panel String and i am not sure if i am able to do it or not.

Here is the panel datasheet





So if we go by PV Input Voltage, a 9 panel string would produce a max 432.9 based on Voc, but i would exceed the PV Array MPPT Voltage Range of 150 - 425V.

Can anyone tell me the difference and am i able to get away with a 9 panel string?

 

[BentleyJ]

PV Input Voltage 125 - 500V: 125V is the minimum input voltage before the input will wake up. 500V is the absolute maximum voltage the electronic components can withstand before permanent damage can be done.

MPPT Range is when the Maximum Power Point Tracking feature will work.

Not sure which panel model you have but they are all around 50Voc. This is 450V at 25 deg C. We would need to calculate a temp corrected Voc for your geographic area to determine if 9 panels in series is acceptable.

 

[BentleyJ]

When calculating MPPT input voltage, Panel Vmpp is used. This is a lower value than Voc, between 38V and 41.7V. Lets call it 40. So 40V x 9 = 360V well within the MPPT range of the inverter.

 

[drakejest]

500V is the absolute maximum voltage the electronic components can withstand before permanent damage can be done.

What do you use to calculate how much voltage my string have? the Voc?

MPPT Range is when the Maximum Power Point Tracking feature will work.

i see, so i should not exceed this value using Vmpp.

i assume you need the coldest temp and the hottest temp in my country is 12C so lets say 10C to be safe (happened in 1960s) hottest is 45C (again in 1960s ). I plugged this in a calculator and it said:



Does that mean i could not do a 9 string setup?

 

[BentleyJ]

The calculation shows that you can in fact have a 9 panel string and it will not exceed 500V even at 10C.

The string would also be within the MPPT range even at high temperatures.

 

[drakejest]

The calculation shows that you can in fact have a 9 panel string and it will not exceed 500V even at 10C.

The string would also be within the MPPT range even at high temperatures.

ahhh i get it now, so its saying that the maximum Voc i can have is 448.48v and my Vmp should be greater than 308.16v

 

[BentleyJ]

the maximum Voc i can have is 448.48v and my Vmp should be greater than 308.16v

Yes, The maximum Voc you will have at 10 deg. C.

 

[drakejest]

Yes, The maximum Voc you will have at 10 deg. C.

but isnt 448V higher than my PV Array MPPT Voltage Range? (150 - 425V)

 

[BentleyJ]

but isnt 448V higher than my PV Array MPPT Voltage Range? (150 - 425V)

The panels will not operate at Voc they operate at Vmpp. As soon as the charge controller wakes up at 150V it will start pulling current and the Voltage will fall to somewhere around the Vmpp value which is less than 425V.

The only time Voc comes into play is if the charge controllers are set for no float and shut off completely or for some reason the PV breaker or disconnect is turned of. Under these conditions the array voltage can climb to Voc when no current is flowing.

 

[drakejest]

The panels will not operate at Voc they operate at Vmpp. As soon as the charge controller wakes up at 150V it will start pulling current and the Voltage will fall to somewhere around the Vmpp value which is less than 425V.

The only time Voc comes into play is if the charge controllers are set for no float and shut off completely or for some reason the PV breaker or disconnect is turned of. Under these conditions the array voltage can climb to Voc when no current is flowing.

So what happens then if for example i had the breakers off at noon (string voltage is at Voc) then flipped the breaker on? would the mppt get damaged?

Because this is a likely scenario, for example when doing maintenance on the roof or cleaning the panels and afterwards the breakers will be turned on

 

[jorby]

That could be a problem. That is why the string voltage while cold should not be higher than the controller input maximum. Then you do not have to worry about it.

 

[Brucey]

So what happens then if for example i had the breakers off at noon (string voltage is at Voc) then flipped the breaker on? would the mppt get damaged?

Because this is a likely scenario, for example when doing maintenance on the roof or cleaning the panels and afterwards the breakers will be turned on

He's saying use the voc number accounting for record cold temps for the max voltage limit, this is never exceed.

And then use vmp to calculate your working range voltage to remain within that range (soft limit, no damage).

Then there can be no damage at voc.

 

[hybe022]

For reference this vietnamese guy is running a luxpower inverter 530Voc, 125-425mppt
on dual 10s 515Voc, 432Vmp

i'm not sure what he will do on winter, if he doesn't remove 1 panel
it probably will go boom. absolute bonkers.

10s panel on Luxpower