Noob getting closer to pulling the trigger on upgrading from 12v AGM to 48v lithium, need validation/correction

[HalfBaked]

Second post, reading constantly, but still very noob.

My current plan is to upgrade from 12 to 48v offgrid. I've been trying to cram knowledge as quickly as possible as my current system requires a few hours of generator every evening to make it through the night. The AGMs are dying.

After strongly considering the cheapest (AIO) routes, then reading more here, I am now leaning towards a more reliable, modular tier 1ish approach.

I currently use the Magnum 2812 inverter/charger and Morningstar ts-mppt-60 with 3kw of scattered arrays. Both units have performed flawlessly for 4 years, which also helped nudge me towards reliability.

The plan -

Continue to use the ts-mppt-60 as it seems 48v lithium compatible through the custom user settings.

Buy from current connected:

Victron 48V MultiPlus-II UL1741 3kVA 120V Inverter 35A Charger

SOK 48V 100Ah (x4)

My needs are small (to me), roughly 8kwhr/day for everything except a 14btu (1200w) AC window unit, that I currently run on generator as needed. It would be super nice to be able to run that from solar for 8ish hrs a day. The next upgrade (maybe next year, as funds permit) will be a mini-split, ideally the type with it's own dedicated panels.

I see scary discussions about victron add-ons and how they get costly. Eg Cerbo gx, Lynx, etc. I just need a simple, reliable system. I have no need for external monitoring or any other special needs.

Questions:
Will I need these extras?
Will my old SCC play well with the Victron inverter and SOC batteries?
Will my current dirty-power generator play well with the victron or will I need some sort of "chargeverter"?
Am I missing any components?
Better plan, knowledge gaps, anything else I should be thinking about?

Thanks everyone for your time and expertise as I learn the ropes.

 

[DIYrich]

If I were you, I would buy the battery and run it as a 12v system. When you need to upgrade to more power, then decide on a 48v system.

If you want to run the AC now, figure out how many panels, and how much battery you will need. Consider going to a 240v system if there is a chance you will need it for future ac.

 

[HalfBaked]

Thanks for the suggestion, I considered this as well, Magnum now has lithium profiles for my unit. The downside, as I understand it, would be the 12v lithium battery can't be connected in series so it cannot work in a 48v system. I don't like the idea of spending big money on something that I can't use in the future.
Or am I way off?

8hrs x 1200w = 9600whrs or about 2 lithium batteries, which is why it seems I need 4 of the batteries. 2 for my daily loads, 2 for AC, if my math is close.

 

[DIYrich]

Diy battery? 32 200ah cells would be equivalent. Wire them as 12v packs. When you are ready to go to 48v, they can be rearranged.

 

[HalfBaked]

That's a thought, but a whole new rabbit hole I'm not ready to go down as I have all limbs in different rabbit holes at the moment.
I do appreciate your help though.

 

[DIYrich]

This 12v sok can be connected in series to provide 48v

SOK 100Ah 12V LiFePO4 Deep Cycle Battery | SOK Battery

In stock,Ready to ship.Latest V8 version Bluetooth BMS, top battery cells balance function.Support connect in series and in parallel.

www.us.sokbattery.com

 

[HalfBaked]

True, that's a possibility, but if I do go down that road, and decide later to go 48v, I'll end up paying over $2000 for the equivalent to a 100ah 48v battery. A difference of about $400/ea x 4 batteries=$1600 more expensive, which is about the same cost as the new inverter.

 

[wiseacre]

All the bells and whistles are nice but not necessary. Detailed info helps understand how the system is performing but doesn't enhance it.
Bottom line, a system should just work without constant surveillance.

Current Connected also offers a cheaper version of the 48v rack battery

If you're half serious now about to going to a higher voltage system it's almost inevitable you'll want to in the future.
For that reason it's best to get the 48v batteries, configuring 12v in series to 48v presents another rabbit hole with keeping them balanced.

About the only extra I'd consider is buying the rack to hold the batteries. Your current SCC is fine

Email Current Connected, they're great at answering questions and recommending components to suit your needs
You could also try sending Dexter a private message here on the forum. He pops in and out frequently: HighTechLab

 

[HalfBaked]

Thanks for all that, I will try reaching out to CurrentConnected. I know, in the end, they need to sell stuff and may not be the best place to ask broad questions, which is why I started here.

Thanks y'all.

 

[Brett V]

If you ever want to expand, 12 and 24volt components get left behind quickly.

 

[Watts Happening]

Do you truly foresee a significant change in both power production and consumption in the near future?

If you don’t, then I’d personally seriously consider just getting however many 12v server rack batteries as you want/need.

Don’t get me wrong here, everything I use is 48v and I generally wouldn’t suggest starting a new system at 12v, even the RV’s I do don’t use 12v as a system voltage, but that doesn’t mean you need to scrap all of your functional, quality equipment out.

I have “cheap” 48v Growatt inverters collecting dust in the garage, I have Victron inverters in my small trailer, both have performed flawlessly. I would however say that with Victron you’ll likely be tempted to get more and more. A Cerbo GX is a great piece of kit, especially with the SOK batteries. It’s certainly not inexpensive, but it does simplify wiring vs using a SmartShunt which I’ve never found to be “totally accurate”. Especially when comparing to the already existing internal shunt information coming from server rack batteries.

12v does have its limitations, but it sounds to me like you’re not reaching them.

 

[HalfBaked]

Thanks for your thoughts. Yes, I also am not happy about buying a new inverter when mine is working well. I also agree my loads are small and are well serviced at 12v.

The reasons why I think I need to upgrade to 48v are:
1) my scc can accept 3-4x more pv input
2) smaller wires, more efficient, less heat
3) SOK doesn't seem to make a 12v 400ah lithium battery

The biggest of these is #1. I have a limited view of the sky and I'm getting clipped at 800w. Then I'm lucky to be able to make it to float. But maybe this is less of an issue with lithium in general as they charge faster?

 

[Watts Happening]

Thanks for your thoughts. Yes, I also am not happy about buying a new inverter when mine is working well. I also agree my loads are small and are well serviced at 12v.

The reasons why I think I need to upgrade to 48v are:
1) my scc can accept 3-4x more pv input
2) smaller wires, more efficient, less heat
3) SOK doesn't seem to make a 12v 400ah lithium battery

The biggest of these is #1. I have a limited view of the sky and I'm getting clipped at 800w. Then I'm lucky to be able to make it to float. But maybe this is less of an issue with lithium in general as they charge faster?

SOK does not have a 12v server rack battery, signature solar does though. I have SOK 48v batteries and am happy with them.

Charge controller can certainly accept 4x the power, and your copper/heat statements are true.

Just have to run the math and see what upgrading everything will cost you, and decide if it’s worth it.

I hadn’t thought about your controller being maxed out, how much power would you guess you could be making throughout the day? IE is 800w out of your 3,000w considered good, or are you leaving close to 2kw unused all day long? I don’t know what your arrays are, nor how much sun they are getting.

 

[HalfBaked]

All 3 arrays are in a tight window through trees and is only clipped when it his 800w in the morning for a couple hours, otherwise they are partly shaded.

I have 1560w facing east for morning array. 1155 south, 300 west. I can only expect 50-60% of nominal from them, so I will need to double my pv.

I'm currently sold on sok, just from what I've read here so far.

In thinking further, to get reasonable use from my battery bank, I should get 5, so about 25kwh. If I charge to 90% and discharge to 20%, that's 25k -30%=17.5k÷6hrs sun = ~3kw pv/hr, which means I'll probably need to go 48v. Do I have a choice?

 

[Tomthumb62]

Yes, I also am not happy about buying a new inverter when mine is working well.

I was in the same boat. Except instead of switching from 12v to 48v (we stayed with 12v for our small system), we wanted a smaller inverter and one that was overall more efficient (we are now consuming 72Wh per day for inverter self-consumption vs 576Wh, big difference when your battery bank is only 200Ah. We went from a 2000W Renogy to a 1000W Victron (the Victron has an ECO mode which saves quite a bit of power and this mode works for our use case, which is to power a fridge in a camp trailer).

 

[Rocketman]

Yes the Victron will play nice with any 48v lithium batteries.

Find a Victron dealer that will program the Multiplus for you. Then you won’t need anything else for the Multiplus. However, you may want to get the ve.bus smart dongle. That way you can adjust the input amps from a generator. (Also you can see the the inputs and outputs data).

Will you batteries ever be subjected to below 32F? (It will ruin batteries if they are charged below 32F).

You may want a shunt based battery monitor- if so look at a Victron Smartshunt.

Good Luck with your project.

 

[HalfBaked]

I was in the same boat. Except instead of switching from 12v to 48v (we stayed with 12v for our small system), we wanted a smaller inverter and one that was overall more efficient (we are now consuming 72Wh per day for inverter self-consumption vs 576Wh, big difference when your battery bank is only 200Ah. We went from a 2000W Renogy to a 1000W Victron (the Victron has an ECO mode which saves quite a bit of power and this mode works for our use case, which is to power a fridge in a camp trailer).

This is a good point, as my current inverter uses about 35w idle, 840wh/day is a whole nother fridge. I think the Victron mp is 11.

 

[HalfBaked]

Yes the Victron will play nice with any 48v lithium batteries.

Find a Victron dealer that will program the Multiplus for you. Then you won’t need anything else for the Multiplus. However, you may want to get the ve.bus smart dongle. That way you can adjust the input amps from a generator. (Also you can see the the inputs and outputs data).

Will you batteries ever be subjected to below 32F? (It will ruin batteries if they are charged below 32F).

You may want a shunt based battery monitor- if so look at a Victron Smartshunt.

Good Luck with your project.

Thanks for the input.
I noticed CC will program the Victron in advance, which is nice.
If the ve.bus smart dongle is the one that allows you to access settings via a PC, this makes sense.
The batteries would be in the house, so never 32.
I'll look at the shunt, thanks.
I'm looking at the budget versions of the sok 48/100. Will I be sorry for not getting the pro" version?

 

[Tomthumb62]

This is a good point, as my current inverter uses about 35w idle, 840wh/day is a whole nother fridge. I think the Victron mp is 11.

You can also sell your old inverter to help defray the costs of your new one. Our Renogy was barely used and so we were able to sell it for a decent price. Victron has some of the lowest idle draws of inverters out there. Samlex is another but not sure if they make AIO units or not.