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24/48v panels into 12v EVE 280 Lifepo4 suggestions

Fibonacci727

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I have 2 sp003 rockpals solar panels and I’m currently building a camper


For the moment I need to make use of these panels and make them work with a victron MPPT to charge a 4 cell EVE 280 12v bank, which I haven’t purchased yet.

The questions are:

Will the panels (24v) be better suited for this in series or parallel into the MPPT?

Will I be losing a lot of charging current by running these panels at 24 or 48v into a 12v battery?

Which Victron is most appropriate for this?

Do I still need a BMS?

Does victron make a BMS that harmonizes with their MPPT?

Will it be more efficient (albeit much more expensive) to run a 24v batter setup?

Any inverter recommendations for this setup? 2000w ish pure sine…

Is there anything I’m forgetting about?
 

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Where are you getting the 24V and 48V references from? The 100W panels you referenced have a Vmp of 18V which by typical marketing terms would be referred to as a "12V" panel. But none of that matters when using an MPPT SCC. You just need to make sure your panel array voltage is 5V higher than your battery charge voltage. Since you will be building a 12V LiFePO₄ battery, your charge voltage will be about 14.4V so you need a panel array voltage of about 20V.

Since these 100W panels have a Vmp of 18V you must put the two panels in series to get enough voltage. With 200W on a 12V battery you can get at most about 16A of charge current. It will be more like 14A with a charge voltage of 14.4V. And it will be even less since you will rarely get the full 200W out of the solar panels. The Victron 75/15 would be more than big enough if you will never have more solar than the two 100W panels in series. If you think you might expand to 4 100W panels total sometime in the future then you might want to get the Victron 100/30 which will easily handle the 4 panels in either 4S or 2S2P.

Do I still need a BMS?
Absolutely. All LiFePO₄ batteries must have a BMS. Don't even consider not using a BMS for your battery.

Does victron make a BMS that harmonizes with their MPPT?
You don't really need to worry about having your BMS communicate with the SCC. Use whatever BMS you want. Then consider adding a Victron SmartShunt battery monitor.

Will it be more efficient (albeit much more expensive) to run a 24v batter setup?
It depends on the rest of your system. Once you get to wanting a 3000W inverter or large you definitely want to go higher than 12V. If your solar needs grow to over 800W then going with 24V would be a good option. You just need 8 cells instead of 4 cells to make a 24V battery. But with your meager solar and a 2000W inverter I see no reason to go beyond 12V.

Any inverter recommendations for this setup? 2000w ish pure sine…
Since you've mentioned Victron several times then you might as well look at the MultiPlus. They make a 12V 2000VA (1600W) inverter. Or if that's not big enough you can go to the 3000VA (2400W) model.

Is there anything I’m forgetting about?
Fuses? Breakers? Proper wire sizes? Bus bars? PV disconnect?
 
Where are you getting the 24V and 48V references from? The 100W panels you referenced have a Vmp of 18V which by typical marketing terms would be referred to as a "12V" panel. But none of that matters when using an MPPT SCC. You just need to make sure your panel array voltage is 5V higher than your battery charge voltage. Since you will be building a 12V LiFePO₄ battery, your charge voltage will be about 14.4V so you need a panel array voltage of about 20V.

Since these 100W panels have a Vmp of 18V you must put the two panels in series to get enough voltage. With 200W on a 12V battery you can get at most about 16A of charge current. It will be more like 14A with a charge voltage of 14.4V. And it will be even less since you will rarely get the full 200W out of the solar panels. The Victron 75/15 would be more than big enough if you will never have more solar than the two 100W panels in series. If you think you might expand to 4 100W panels total sometime in the future then you might want to get the Victron 100/30 which will easily handle the 4 panels in either 4S or 2S2P.


Absolutely. All LiFePO₄ batteries must have a BMS. Don't even consider not using a BMS for your battery.


You don't really need to worry about having your BMS communicate with the SCC. Use whatever BMS you want. Then consider adding a Victron SmartShunt battery monitor.


It depends on the rest of your system. Once you get to wanting a 3000W inverter or large you definitely want to go higher than 12V. If your solar needs grow to over 800W then going with 24V would be a good option. You just need 8 cells instead of 4 cells to make a 24V battery. But with your meager solar and a 2000W inverter I see no reason to go beyond 12V.


Since you've mentioned Victron several times then you might as well look at the MultiPlus. They make a 12V 2000VA (1600W) inverter. Or if that's not big enough you can go to the 3000VA (2400W) model.


Fuses? Breakers? Proper wire sizes? Bus bars? PV disconnect?
Thank you for all of this. It helps a ton.

I just assumed they were marketed that way as on Amazon it’s listed as a 21.6 output voltage. I am aware of the 18v nominal tho but I’m still new to all this so learning still.

And yes I have the fuses and breakers, bus bars, main shutoff and appropriate gauge wire to get it all together or will buy what I’m missing when I start building.

As far as the victron bms I was hoping their app would put it all together in a nice neat package so I can monitor it all from my phone in 1 app. That’s the hope anyway. I will pay a bit extra to streamline it that way if it’s possible.

I’ll look into that inverter. I’m sure it’s pricey. Buy once cry once tho, eh? It’s only fake, ever increasingly worthless fiat money tho, eh? ?

Thanks again
 
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