New inverter

[Jjh]

So hears the plan. Im not exactly new to solar or solar systems but this inverter is going to make me redesign my system I think. I am looking at 2w lv6548's. Currently I have 1 magnum 4448 inverter. We have not set up our array yet but have 12 255 watt Canadian solar panels want to run them in 6p2s. Currently we are just charging for 2.5hr off a portable genset. I want to add a minisplit and we are adding an addition to the house. Also our all time record high is 109 and low is -8 any help would be great and if i need anymore info please let me know.

my panel specs are as follows

pmax 255
vmp 30.2
imp 8.43
voc 37.4
isc 9.00

stc is 25 degrees C.

 

[pollenface]

At -8F multiply the VOC by 1.2 = 89.76v

 

[Jjh]

At -8F multiply the VOC by 1.2 = 89.76v

I'm confused how you got this now I really feel dumb

 

[Hedges]

Check the data sheet for your PV panels. Do they list Temperature Coefficient of Voc? If so you can compute the voltage rise more precisely.
Otherwise, we probably use a safe rule of thumb.

 

[Bud Martin]

I'm confused how you got this now I really feel dumb

I use 20% for worst case cold temperature.
2 panels in series, total Voc 37.4V x 2 = 74.8V, so +20% = 74.80V x 1.2 = 89.76V.

Calculating Max PV Voltage is Not Scary - Sunny. SMA Corporate Blog

In 2008, the National Electrical Code (NEC) added a second paragraph to 690.7(A) stating, “When open-circuit voltage temperature coefficients are...

www.sma-sunny.com

 

[Jjh]

I use 20% for worst case cold temperature.
2 panels in series, total Voc 37.4V x 2 = 74.8V, so +20% = 74.80V x 1.2 = 89.76V.

Calculating Max PV Voltage is Not Scary - Sunny. SMA Corporate Blog

In 2008, the National Electrical Code (NEC) added a second paragraph to 690.7(A) stating, “When open-circuit voltage temperature coefficients are...

www.sma-sunny.com

so if i have this right if I do six in series 37.4 x 6 = 225.6 +20% = 225.6 x 1.2 = 270.72 which puts me over the 250 vdc on these inverters

 

[Bud Martin]

so if i have this right if I do six in series 37.4 x 6 = 225.6 +20% = 225.6 x 1.2 = 270.72 which puts me over the 250 vdc on these inverter

That will be the worst case and you will exceed the input limit of the Solar Charge controller spec if the max input spec of the Solar Charge Controller is 250Vdc (the input may have extra head room that may tolerate slightly higher than the published spec, but that number is not published for us to see)

 

[Jjh]

That will be the worst case and you will exceed the input limit of the Solar Charge controller spec if the max input spec of the Solar Charge Controller is 250Vdc (the input may have extra head room that may tolerate slightly higher than the published spec, but that number is not published for us to see)

guess I will have to look at another inverter as I don't want to take the risk

 

[Bud Martin]

What is the MPPT Voltage range of the LV6548?
Is there a reason why you are looking at the LV6548 SCC/INVERTER?
Are you still going to use Magnum 4448 inverter?
What are your batteries capacity and type?

 

[Jjh]

90-230 VDC no I'm removing the magnum was going to get 2 of the lv6548. Need the ability to draw more power as we are adding an addition and a mini split ac unit 600amp hr 48 volt lithium ion

 

[Bud Martin]

You can do 4S2P for PV1 input, 4S for PV2 input.
VOC at 37.4V x 4 x 1.2 = 179V (it is below max PV input limit of 250Vdc)
Each panel string Vmp = 30Vmp x 4 = 120V which is within MPPT Voltage range (90 ~ 230V).
Each panel string will have Isc of 9A, total Isc for PV1 input = 9A x 2 = 18A (two strings in parallel)
Isc for PV 2 will be 9A (only one string of panel).

Some one else may have other suggestion as well.

LV6548 6.5KW – 120v Solar inverter 8kW -2 x 4kW 250V MPPT UL1741 compliant – built in Wifi – Special – Watts247 Wholesale

watts247.com

 

[Jjh]

Why didn't I think of that thanks!!! Brain been on overload today I guess.