Wiring Panels in Series-Parallel | Is this diagram correct?

[Bud Martin]

145vdc PER SIDE so technically 290vdc total. Because it’s two inverters in one unit

So 145vdc Max for each MPPT PV input.
Post #1: Solar panels: (18) 250w VPM 30.3v. Max power current 8.27a
What is the Voc of the panel?

 

[MisterSandals]

How about 1 array as 5S2P and the other 4S2P?

This works fairly easily if you can configure your arrays physically this way.

 

[AZ Off-Gridder]

So 145vdc Max for each MPPT.
What is the Voc of the panel?

VOC is 37.6v
VMP is 30.3v

 

[Bud Martin]

How about 1 array as 5S2P and the other 4S2P?

This works fairly easily if you can configure your arrays physically this way.

His max PV input is 145VDC, his unit is dual MPPT.

 

[AZ Off-Gridder]

How about 1 array as 5S2P and the other 4S2P?

This works fairly easily if you can configure your arrays physically this way.

Plan has been to mount them on a pole too mount it’s a big 3x3 square essentially. With enough MC4 extensions I would guess any configuration is possible. Let me do that numbers real quick to see what your idea would get me for math. Thanks.

 

[Bud Martin]

VOC is 37.6v
VMP is 30.3v

That means max will be 3 panels in series since your SCC max PV input is 145VDC..
37.6V x 3 = 112.8V, it will be higher at low temp.

 

[AZ Off-Gridder]

His max PV input is 145VDC, his unit is dual MPPT.

Yeah so it seems string of 4 is really my limit. And even then maybe too close at 121v out of the 145max.

 

[AZ Off-Gridder]

That means max will be 3 panels in series.

Yeah that’s what I thought to be so, i appreciate the verification I’m glad I’m not terribly far off the mark there

That being said what’s the best next move now that we know the 3 string limitations?

 

[WYtreasure]

That was my initial thought. But in another post I was cautioned against high-voltage DC due to safety reasons… I’m open to anything I just want a solid system that works, lasts, and is safe. And as far as temps go it’s Arizona Desert valley at around 2,200ft so annual highs are 105f and lows maybe 45f for daytime temps.

I would be concerned about running HIGH VOLTAGE as well. It's a trade-off: Lower voltage wants bigger wire. GO BIG ?

Deserts get mighty cold, I'm old, been there done that.
Check with the weather service to find the lowest temp on record.
Drop that temp by 10 or 20 degrees, at least that's what I would do, and call that the lowest temp.
Take that lowest temp to a tool like this to ensure you do not fry your MPPT with high voltage in the early morning.

MidNite Solar - Classic Sizing Tool.

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

 

[Bud Martin]

You have 18 panels total, so it looks to be
3s3p for each PV input.

 

[AZ Off-Gridder]

stupid questions here. But because my array is oversized for my needs what’s the problem with having some DC power loss through the 10 AWG wire at 130feet? Even if it was 5% loss (it’s not) but that still leaves me with plenty of power. Is it “wrong” because your wasting\losing power? Or is there another factor to consider like safety or something I’m missing. Wire ain’t cheap… but if there’s solid reasoning I’m all for getting it done right. These panels sell for $58usd a pop, wire on the other hand is much more

 

[Bud Martin]

Do you already have the 10AWG wires?
If you can live with calculated loss, that will be OK.
$58 each for the panel is a good deal.
I think you will be OK.

 

[AZ Off-Gridder]

Take that lowest temp to a tool like this to ensure you do not fry your MPPT with high voltage in the early morning.

Great information thanks. And here’s my results.

 

[WYtreasure]

stupid questions here. But because my array is oversized for my needs what’s the problem with having some DC power loss through the 10 AWG wire at 130feet? Even if it was 5% loss (it’s not) but that still leaves me with plenty of power. Is it “wrong” because your wasting\losing power? Or is there another factor to consider like safety or something I’m missing. Wire ain’t cheap… but if there’s solid reasoning I’m all for getting it done right. These panels sell for $58usd a pop, wire on the other hand is much more

Damn good point.

I saw an energy loss in your wires and ran screaming down the block... THE SKY IS FALLING ?

 

[AZ Off-Gridder]

Do you already have the 10AWG wires?

No but seems to be the standard for PV wire, there so much for sale in bulk everywhere and it’s fairly cheap. I’m not locked in on a wire size yet just asking all the questions I can to learn and make educated decisions

 

[MisterSandals]

Inverter: MPP LV6048 6kW

Do you already own this?

 

[AZ Off-Gridder]

Do you already own this?

No not yet. Do you have any experience with this one? Or, Is there something better for my application?

 

[MisterSandals]

Do you have any experience with this one? Or, Is there something better for my application?

I do not have experience with that one or any large home inverters (but researching my next system!).

I would strongly consider something that accepts a much higher input voltage so that you can make your array and wiring more manageable.

 

[AZ Off-Gridder]

I do not have experience with that one or any large home inverters (but researching my next system!).

I would strongly consider something that accepts a much higher input voltage so that you can make your array and wiring more manageable.

Ok well MPP makes the exact same inverter but it’s the LVX 6048 and it’s got a Mac PV input of 450vdc. I was kinda scared of that unit just because it’s brand spanking new and I can’t find anyone who’s got one to review it yet. And also 450vdc sounds terrifying haha. But MPP is a great company and I know they stand by their stuff. Similar price so I can definitely switch plans and get the LVX high volt model

 

[AZ Off-Gridder]

Here’s the LVX High Volt Model MPP
Note this unit is only 1 big MPPT, not 2 side by side. So one large PV input only.

Thoughts of using this beast?