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PV Array size and inverter compatibility?

titsmcgee

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I have 28 x Hanwha Q.Plus L-G4.2 340 watt panels, VMPP = 37.63, IMPP = 9.03, VOC = 47.07, ISC = 9.59

I also have 2 x Phocos Anygrid 6.5 kWh inverters.
  • Up to 250 Volt DC dual-MPPT for solar PV
  • Integrated 120 Amp AC charge controller
  • Integrated 120 Amp MPPT solar charge controller
So, how should I configure the array? I was thinking of doing 4 strings of 7, that would put me 378.91 VOC for each string (with 15% included). The inverter has dual-mppt up to 250 Volts. So, do I need another inverter(s) and do smaller strings of 4? That would put me at 216.52 VOC per string, per MPPT, is that correct or am I doing my math wrong?
 
I have 28 x Hanwha Q.Plus L-G4.2 340 watt panels, VMPP = 37.63, IMPP = 9.03, VOC = 47.07, ISC = 9.59

I also have 2 x Phocos Anygrid 6.5 kWh inverters.
  • Up to 250 Volt DC dual-MPPT for solar PV
  • Integrated 120 Amp AC charge controller
  • Integrated 120 Amp MPPT solar charge controller
So, how should I configure the array? I was thinking of doing 4 strings of 7, that would put me 378.91 VOC for each string (with 15% included). The inverter has dual-mppt up to 250 Volts. So, do I need another inverter(s) and do smaller strings of 4? That would put me at 216.52 VOC per string, per MPPT, is that correct or am I doing my math wrong?

250V limit means 250V limit. You can't go over that, and you need margin.

72 cell panels (yours) max 4S on a 250Voc PV input.

If it's this one, yours also has PV input current limitations:


1663737279060.png

It also appears that you can only have 22A input into each MPPT, but it may only use 36A total between the two. The most you can put on each MPPT is 4S2P and not exceed those limits. As you can see, it's pretty much impossible to get anywhere near 4000W on each MPPT. The closest you can get is with ~340W 60 cell panels if you can find them. You could go 6S2P. That would put you at about 4000W total, but they'd get clipped from 22A to 18A resulting in about 3300W.

IMHO, these and other 250V PV limit inverters with an ~18A PV current limit are a mistake. They make it impossible for you to attain the claimed array power.
 
250V limit means 250V limit. You can't go over that, and you need margin.

72 cell panels (yours) max 4S on a 250Voc PV input.

If it's this one, yours also has PV input current limitations:


View attachment 112771

It also appears that you can only have 22A input into each MPPT, but it may only use 36A total between the two. The most you can put on each MPPT is 4S2P and not exceed those limits. As you can see, it's pretty much impossible to get anywhere near 4000W on each MPPT. The closest you can get is with ~340W 60 cell panels if you can find them. You could go 6S2P. That would put you at about 4000W total, but they'd get clipped from 22A to 18A resulting in about 3300W.

IMHO, these and other 250V PV limit inverters with an ~18A PV current limit are a mistake. They make it impossible for you to attain the claimed array power.
So, If I have two of these inverters does my total amperage equal 72amps, assuming I'm able to maximize the limit? Idk, if I'm asking that correctly. If it does equal 72 amps in that scenario, would that be adequate for a home? To be specific I want to use this system to power a few campers initially, and plan to build either and earthbag home (a couple domes connected) or cordwood home, in both scenarios I plan to use wood stove heating and add a minisplit. Or, if 72 amps is not enough should I buy another inverter to bump it to 100-108amps, or I guess I can sell them (I'd hate to do that) and buy a couple LV 6548's.

Edit: Hold on, looking at the LV 6548's they are limited to 18a too correct, as are the Solark 12kWh inverters per MPPT (so, x'2) is that correct? Or am I reading that wrong? If that is correct, wouldn't that severely limit what one can power? Is there a workaround, can I add additional MPPT's? That's probably a dumb question but I have to ask. Worst case scenario, If i can power a few deep freezers and a minisplit I can probably manage with the rest. I wont be using a stove, just airfryer, toaster oven or instant pot and maybe a few fans and computers, 1 TV, occasional tool and phone charging, and that I can run of the grid.
 
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So, If I have two of these inverters does my total amperage equal 72amps, assuming I'm able to maximize the limit?

Each unit has 2 MPPT capable of using 18A of input PV, thus 4 * 18A = 72A total input.

Idk, if I'm asking that correctly. If it does equal 72 amps in that scenario, would that be adequate for a home?

That depends on the loads, their duration, etc.

Have you conducted an energy audit and designed a system accordingly?

To be specific I want to use this system to power a few campers initially, and plan to build either and earthbag home (a couple domes connected) or cordwood home, in both scenarios I plan to use wood stove heating and add a minisplit.

This might feel specific to you, but it is actually very vague and incomplete. See energy audit above.

Or, if 72 amps is not enough should I buy another inverter to bump it to 100-108amps, or I guess I can sell them (I'd hate to do that) and buy a couple LV 6548's.

I'm not sure why you've focused on 72A. I don't think you understand the MPPT. Let's try a summary of a MPPT PV charger and it's limitations. See Phocos specs below:

1663815889799.png

1: this is the maximum OUTPUT of the MPPT, 120A (60A + 60A). No matter how much solar you have, you can never output more than 120A. Since power is voltage * current, the output POWER will vary with voltage. PEAK output power is about 57.6 * 120 = 6,912W (3456W x2) - it can NEVER be more than this.

2: limit of the solar panel series voltage. It must be under 250Voc. To allow for cold temp voltage increase, you want to leave about 15% margin, so no more than 4S of your panels on an MPPT. 188.28Voc, 150.52Vmp, Imp = 9.03A, and Isc = 9.59A

3: This is the range of panel voltage where the MPPT can function optimally. You won't get charging above or below those voltages.

4: Is is the maximum amount of current your array can put out INTO the MPPT. While you can have UP to 22A on each, the most it will use is 36A, so lets use 18A per MPPT. Given your panels and their 9.59A Isc, they're pretty well suited current-wise. On each MPPT, you can have 4S2P panels, so your array will output a maximum of 150.52V * 18A = 2709W. It will never output more than this except in excellent solar conditions and cold weather.

5: This is an upper limit on the output, and it's pretty close to the peak MPPT operating voltage and max current: 230V * 18A = 4140W.

6: This is an over-paneling limit. Regardless of how you configure the array, you shouldn't put more than 5000W on each MPPT.

All of the above influence your array configuration and your MPPT output. If any single value is exceeded, THAT value becomes the limiting factor on the array output.

Consider also that you're using high consumption inverters. The Phocos claim about 50W. 2X would be 100W or 2.4kWh/day. Your first 500W of your array is dedicated to replacing what the inverters consume without powering any loads. Furthermore, 2.4kWh of batteries will be unusable for loads because they're feeding the inverter. That amount of battery is expensive... about $700 if you're buying 48V EG4 type batteries.

The LV6548 are worse. They burn about 100W each, so that's 200W or 4.8kWh/day - nearly the full capacity of a $1445 EG4 batter requiring 1000W of your array to feed it.
 
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