EG4 18KPV MPPT Input and Output per leg

cdstyle said:

The EG4 18K PV has the following spec for PV Input

AC Input Data
MAX. AC INPUT POWER - 12000W
PV INPUT DATA
NUMBER OF MPPTS - 3
INPUTS PER MPPT - 2 (MPPT 1) | 1 (MPPT 2) | 1 (MPPT 3)
MAX. USABLE INPUT CURRENT - 25A (MPPT 1) | 15A (MPPT 2) | 15A (MPPT 3)
MAX. SHORT CIRCUIT INPUT CURRENT - 31A (MPPT 1) | 19A (MPPT 2) | 19A (MPPT 3)
DC INPUT VOLTAGE RANGE - 100-600 VDC
MPPT OPERATING VOLTAGE RANGE - 140-500 VDC

AC GRID OUTPUT DATA
NOMINAL POWER OUTPUT @240v 12000W | @208V 10400W



Question 1.
Do I use the MPPT OPERATING VOLTAGE RANGE or the DC INPUT VOLTAGE RANGE to calculate how many panels I can put in series ?
I assumed I would be using the mppt voltage range of 500 VDC,
but saw this forum post was using DC INPUT VOLTAGE RANGE of 600 VDC to calculate max number of panels in a string, so I wanted to make sure.
I was trying to max out the number of solar panels I can put, with solar panels that has open circuit voltage of 37.07.
If I save 50V to account for voltage spike in low temperature (10% increase in voltage at temperature of 0C/32F), that only leave me with
450/37.07 = 12 panels per string * 4 strings= 48 panels.

Question 2.
It seems like the 18kpv is only able to charge the batteries at a max rate of 12kWh.
Assuming that my pv array is producing 18kW at any given time, and if I am not consuming any power,
can the inverter actually fully utilize the 18kW by saving them to both the battery(if not full, ) and export the rest back to the grid?
Likewise, can the 18kpv export more than 12kW back to the grid?
I know the ac input power of 12kW is per leg, so a 240v breaker can pull 12kW*2 = 24kW,
but don't know if the same thing can be applied when exporting back to grid, which would result in a max export of 24kWh back to the grid.

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Quattrohead said:

500 volts on the PV is the maximum working range but it can take up to 600 without damage, so your 12 panel strings should work unless you're sitting at the North Pole.
Yes the maximum charge is 12 KW but the other six can be exported back to grid at the same time so yes it can use the 18 KW.
However the inverter part is 12 KW whether that is powering load or pushing back to grid or any combination up to 12 KW, except for loads only it can push up to 15 KW for up to 5 minutes.
In bypass or pass through mode it is actually rated for the full 200 amps, 100 amps per leg so it can pass through your full 200 amps or 48 KW in that situation.

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wpns said:

You use the maximum input voltage (600V) to calculate your string length, as real operating MPP will be less than Voc. However, you need to know your minimum temperature to be able to calculate maximum Voc for your panels. 16-panel strings is probably too close to the limit but 15 might work depending on temperature. Extra precision can be achieved if your panel labels include temperature coefficients though you’ll still have an integral number of panels in a string.

Each leg of the inverter can handle 8KW, and the total is 12KW at 240V as in the spec above. Honestly, I have two of them in parallel, and I can’t parse the 18, so I just think of it as a 12 kW all in one.

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cdstyle said:

Yeah, 15 panels barely made it within the voltage at -1°C for 600V

open-circuit voltage (Voc): 37.07
Voltage Uoc (temp coef) of 0.28/°C
Standard test condition of 25°C
expected lowest temperature of -1°C (so 26°C change)
so 26*0.28/100 * 37.07= 2.70 V change
so each panel would have 39.77V
15 panels would clock in at 596.55V

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cdstyle said:

do you know what would be considered as bypass? only power pulled from the grid to help power loads? or does power generated from a pv array stored into the battery in a dc coupled system would also be considered as bypass?

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cdstyle said:

Yeah, 15 panels barely made it within the voltage at -1°C for 600V

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