Solar panel/charge control selection and help

[Nan_wpg]

Hopefully this makes sense as it moves from my head onto the keyboard……

context: diy solar generator 48v 100Ah battery, and Victron multiplus w/35A charger.

looking to panel this thing. No power audit, I’ll connect it to the array.If No sun, then I fire up the generator to the multiplus.

first off, Ive been playing with the Victron mppt calculator. I’m using my own panels but I don’t know what to use to input the v temp, and I temp?

here’s the data sheet of a panel I can buy locally:

https://cdn.shopify.com/s/files/1/0682/6786/8458/files/Hi_MO_4m_LR_4_60_HPB_355_375_M_4eb7d0e7c0.pdf?v=1673555971

Can someone tell me if it has the correct information, and what it is?

as for the CC and panel selection what are “best practices”?

do I match up the CC to the multipluss? (I.e 150/35 to match the multi 35A charge current) if so, do I play around with panels so I get close to 100% pv power ratio? how do I decide the series/parallel issue? It’s about a 50’ run of cable. I know higher voltage = smaller cables, less loss (with less amps)

as for connecting the panels, and assuming breakers to the battery, CC, and inverter are off can the panels be connected, and unconnected safely? I know panels generate electricity but if there’s no load do you still cover them with a blanket?

I can unplug things in my house without turning power off, but dc can arc.

I’m looking to buy 4 of the panels that I linked. The Victron calculator said I’d have about 30ish amps with a 2s2p configuration.
If I wanted a 4s I’d need a bigger controller

 

[sunshine_eggo]

Hopefully this makes sense as it moves from my head onto the keyboard……

context: diy solar generator 48v 100Ah battery, and Victron multiplus w/35A charger.

What is the maximum charge rate of the battery?

looking to panel this thing. No power audit, I’ll connect it to the array.If No sun, then I fire up the generator to the multiplus.

first off, Ive been playing with the Victron mppt calculator. I’m using my own panels but I don’t know what to use to input the v temp, and I temp?

here’s the data sheet of a panel I can buy locally:

https://cdn.shopify.com/s/files/1/0682/6786/8458/files/Hi_MO_4m_LR_4_60_HPB_355_375_M_4eb7d0e7c0.pdf?v=1673555971

Can someone tell me if it has the correct information, and what it is?

coefficients are on the bottom right of the last page:



Try running those numbers and posting the results for discussion.

as for the CC and panel selection what are “best practices”?

do I match up the CC to the multipluss? (I.e 150/35 to match the multi 35A charge current)

No. You match the CC to the needs of the array and the battery voltage.

4 * 365W = 1460W

1460W / 48V = 30.4A (maximum current draw at low battery voltage)
1460W / 56.8V = 25.7A (minimum current draw at peak battery voltage)

if so, do I play around with panels so I get close to 100% pv power ratio?

huh?

how do I decide the series/parallel issue? It’s about a 50’ run of cable. I know higher voltage = smaller cables, less loss (with less amps)

The MPPT calculator should give you some insight.

For the 50' run, you can calculate wiring losses:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

I simulated a 2S2P array of the 365W version.

as for connecting the panels, and assuming breakers to the battery, CC, and inverter are off can the panels be connected, and unconnected safely?

Yes, but you have to treat a potential high voltage source with respect and appropriate precautions.

I know panels generate electricity but if there’s no load do you still cover them with a blanket?

That's a great way to ensure maximum safety, but I've never personally done that.

I can unplug things in my house without turning power off, but dc can arc.

And it will but not when the breakers are open.

I’m looking to buy 4 of the panels that I linked. The Victron calculator said I’d have about 30ish amps with a 2s2p configuration.

Yep.

If I wanted a 4s I’d need a bigger controller

Not really. Bigger generally means higher power. A 250/70 won't give you any more power than a 150/70 as they're both limited to 70A output. You need a controller with a higher Voc allowance, not a bigger controller. Given the 60 cell panels you've selected, 3S is pretty optimal for a 150V controller.

If you want 2S2P, you might want to consider 72 cell panels.

 

[Nan_wpg]

What is the maximum charge rate of the battery?

Trophy recommends “up to 50A” for optimal charging. Less is better. I was shooting for around 30ish amps to match the 30 amp charging current of the multiplus.

coefficients are on the bottom right of the last page:

View attachment 139313

Try running those numbers and posting the results for discussion.

Thanks!

No. You match the CC to the needs of the array and the battery voltage.

4 * 365W = 1460W

1460W / 48V = 30.4A (maximum current draw at low battery voltage)
1460W / 56.8V = 25.7A (minimum current draw at peak battery voltage)

I,get that but I’m not designing “properly”. I kinda just want to charge a 48v 100a battery reasonably

huh?

The power ratio is on the Victron calculator. Overpanel,is over 100%, it tells you if your choice of panels is optimized as a % value

The MPPT calculator should give you some insight.

For the 50' run, you can calculate wiring losses:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

I simulated a 2S2P array of the 365W version.



Yes, but you have to treat a potential high voltage source with respect and appropriate precautions.



That's a great way to ensure maximum safety, but I've never personally done that.



And it will but not when the breakers are open.



Yep.



Not really. Bigger generally means higher power. A 250/70 won't give you any more power than a 150/70 as they're both limited to 70A output. You need a controller with a higher Voc allowance, not a bigger controller. Given the 60 cell panels you've selected, 3S is pretty optimal for a 150V controller.

I guess I worded incorrectly. When I said “bigger” I meant the higher voltage controller. Not necessarily more amps. Most of the 250 controllers start at 70A.

If you want 2S2P, you might want to consider 72 cell panels.

I realize a 250 won’t give more power than a 150 but it was more so the fact I can select bigger panels.

The only reason I selected the panels that I linked was simply they are available right now, walk in off the street and drive home with them.

I’d consider any panel. Ideally I’m limited to 4 (space constraints) and I’ll likely use the ground Mount signiture Solar sells. It’s limited to 4 panels.

At the end of the day it’s 4 panels to charge the battery. If it’s not enough we fire up the generator.

I suppose I could consider either 5100 watts, or 2550 as my power usage for the day and just plan from there.

 

[Nan_wpg]

I screwed up that response. I tried quoting and commenting like you did when you responded.

My forum skills are weak

 

[sunshine_eggo]

50' run of 2S2P is a 2.98% voltage drop with a single 10awg wire, which equates to a 2.98% power loss. I don't see any issues with it.

The 250 are notably more expensive, and I don't think they're available at the lower currents, so you're be spending a lot of $ to save a little on wire.

 

[Nan_wpg]

50' run of 2S2P is a 2.98% voltage drop with a single 10awg wire, which equates to a 2.98% power loss. I don't see any issues with it.

The 250 are notably more expensive, and I don't think they're available at the lower currents, so you're be spending a lot of $ to save a little on wire.

The Victron calculator isn’t accepting .265 for V temp coefficient? It’s red. Not sure what that means?

 

[sunshine_eggo]

The Victron calculator isn’t accepting .265 for V temp coefficient? It’s red. Not sure what that means?

Are you entering it as a negative number? It's negative.

 

[Nan_wpg]

Are you entering it as a negative number? It's negative.

I missed that. Was entering as a positive.