48v or 12v.. + solar/battery combo for most things.. which way to go?

[beowulf]

Hi all,

New to all this "off grid" stuff. Trying to get situated.. mostly for the future.. but also cause our local energy costs have gone up 3x in price the past 2 years. It's unsustainable now for most who are not wealthy.. giving up the use of AC in 100+ heat, and heat in 20 to 30 degree cold.

So I started down the path of looking at running my most common things outside of the fridge, AC, washer/dryer.. namely TV, computers, even some lights (switching to LED based plug in lights instead of ceiling mounted AC lights).

That led to a whole bunch of things. The DIY battery market seems to be much more affordable, and being a software/hardware engineer, and lots of DIY projects, I am OK with that.

My house has solar (6.5Kw system).. but with the increase in costs.. that barely covers my AC usage apparently in summer. I don't have anything like Powerwall (I have tesla solar).

I have been thinking of setting up a few portable solar panels.. in the back.. with 30fee tor so of cable/wire to bring inside to a LiFePO4 battery bank.. that feeds a power station, which my computer/lights in my office would be plugged in to.

From what I can tell, the EVE 280ah battery set.. 4 of them.. for about $700 USD.. offers 12, 24 or 48v options (each cell is 12v). But I am unclear how to best wire it up if I go that route. I am also unsure if 2 100watt panels would charge it up or not with 10 hours or so of sun.. at least during the 5 or so months of sunlight we get for most of the day.. or if I would need a lot more.. and thus be stupidly expensive.

My initial ask is.. 12, 24 or 48v? I read solar and even cars are headed towards 48v.. since its more stable, efficient.. than 12v. There are also inverters that can convert 48v to 12v (dc to dc) to allow a battery bank to connect to the 12v inputs of a power station (e.g. Yeti 1000 or similar). I want a portable power station as well.. one that I can take with me on camping/road trips.. hence why I am thinking of one of those + a battery bank.

I have been looking at the prices as well. The EG4 LifePower batteries for example.. run about $1500 for one unit.. and 6 of them would give 30Kwh of storage for under $10K. Not that I want to spend anything close to that now.. but thought buying one of those units now.. and building up as needed.. might be a more cost saving route. Not sure how they compare to the 4x12v EVE setup for $700.. still trying to learn all this.

In the states.. I am trying to stay USA company based when it makes sense.. Renology seems to be one of the USA made products.. but who knows.. maybe they source from China.. not sure. But they have a 980wh 1000watt power station on part with yeti/blueyeit/jackery/etc.. for $750.. about $250 or so less than others.. seems like a good price for what you get.

So my thought was.. run the EVE (or EG4) as a rechargeable battery bank.. build up as needed.. in 48v. Charge it by solar when I can, and AC during evening off peak hours if need be. Chain that to the Renology power station.. to keep it charged/topped off.. and plug computer/monitor/LED lights.. in to the Renology so I can avoid using AC during peak daytime/evening hours.

Feel like the EVE battery setup, + 200 or so watt panels.. + renology works out to about $2500 or so total..and should be enough for me to run my WFH setup during day.. and still have ability to take the Renology with me on trips/etc (with panels) as needed.

What am I missing.. how far off am I with all this? Is 12v better than 48v?

 

[400bird]

Welcome!
Sorry I didn't read your entire post, sorry.

Unless you have 12 volt loads, I'd recommend 48 volts.
Also, there's sort of a rule of thumb:
Under 2000 watts - 12 volts
Under 4000 watts - 24 volts
Over 4000 watts - 48 volts

You mentioned Renogy. Not US made, they contract with manufacturers in China to brand products in theory colors.
EG4 does the same.

 

[beowulf]

Ah ok. So my PC + monitor would likely be under 2000 watts. Hence why I was thinking of the portable power station with LiFePO4 battery.. as the way to power it.. and just keep that one charged each night. I am not entirely sure of 980wh of storage would be enough to run my PC for 12 or so hours a day or not though. It fluctuates between 100 and 150w of use.. and I believe monitor uses about 100 or so watts as well (49" Samsung G9 LED). Assuming 300 watts of usage.. then I guess that means this unit would only provide about 3 hours of usage.. but wasn't sure with the whole amperage draw as well if that made a difference.

 

[400bird]

I've got a few more minutes now to respond.

My house has solar (6.5Kw system).. but with the increase in costs.. that barely covers my AC usage apparently in summer. I don't have anything like Powerwall (I have tesla solar).

if you already have solar and are looking at DIY options, I'd recommend looking into AC coupling to what you have now and maybe adding more panels to that new inverter.

From what I can tell, the EVE 280ah battery set.. 4 of them.. for about $700 USD.. offers 12, 24 or 48v options (each cell is 12v).

The 280 ah Eve cells are 3.2 volts each.
4* is 12 volts
8* is 24 volts
16* is 48 volts

But I am unclear how to best wire it up if I go that route. I am also unsure if 2 100watt panels would charge it up or not with 10 hours or so of sun.. at least during the 5 or so months of sunlight we get for most of the day.. or if I would need a lot more.. and thus be stupidly expensive.

Go to PV watts (https://pvwatts.nrel.gov/)
Just because the sun is up for 10 hours doesn't mean you get 10 solid hours of production. The sun moves around the sky and your production with taper in a bell curve sort of shape.

My initial ask is.. 12, 24 or 48v? I read solar and even cars are headed towards 48v.. since its more stable, efficient.. than 12v. There are also inverters that can convert 48v to 12v (dc to dc) to allow a battery bank to connect to the 12v inputs of a power station (e.g. Yeti 1000 or similar). I want a portable power station as well.. one that I can take with me on camping/road trips.. hence why I am thinking of one of those + a battery bank.

I have been looking at the prices as well. The EG4 LifePower batteries for example.. run about $1500 for one unit.. and 6 of them would give 30Kwh of storage for under $10K. Not that I want to spend anything close to that now.. but thought buying one of those units now.. and building up as needed.. might be a more cost saving route.

Seems like you've discovered the two most common options. Buy an inverter and batteries or a "solar generator" type thing.

One is permanently installed and should last a long time.
The other is easily forgotten in a closet, then abused on a camping trip.

Not sure how they compare to the 4x12v EVE setup for $700.. still trying to learn all this.

Not apples to apples. Partially because you've got the quantity/voltage on those cells incorrect and partially because the rack mount batteries are an end user product. Also, you need to build an enclosure, add BMS, fuse, wiring, etc with the raw cells.

In the states.. I am trying to stay USA company based when it makes sense.. Renology seems to be one of the USA made products.. but who knows.. maybe they source from China.. not sure. But they have a 980wh 1000watt power station on part with yeti/blueyeit/jackery/etc.. for $750.. about $250 or so less than others.. seems like a good price for what you get.

None of those are made in the US.
I'm not familiar enough with any of them to discuss the finer details and differences.

So my thought was.. run the EVE (or EG4) as a rechargeable battery bank.. build up as needed.. in 48v. Charge it by solar when I can, and AC during evening off peak hours if need be. Chain that to the Renology power station.. to keep it charged/topped off.. and plug computer/monitor/LED lights.. in to the Renology so I can avoid using AC during peak daytime/evening hours.

Feel like the EVE battery setup, + 200 or so watt panels.. + renology works out to about $2500 or so total..and should be enough for me to run my WFH setup during day.. and still have ability to take the Renology with me on trips/etc (with panels) as needed.

What am I missing.. how far off am I with all this? Is 12v better than 48v?

My only remaining thoughts are that 200 watts of panels isn't going to make much of a dent when you've already got 6500 watts on the roof.

Where are you located? Do you have net metering? Are you willing to do the AC wiring and everything needed to add to the rack mount batteries?

Renogy is not known for being quality, at least not from what I've read here.

 

[Shimmy]

A lot of horror stories with Renology.

Your IT loads are likely under 500W unless you have a massive homelab. Get a kill-a-watt or similar to meter the loads and get yourself a sense of daily energy use. I also recommend adding an IoTaWatt or something similar to help break down large loads to know where your energy really goes-- if saving money is really the core objective.

48V. Anything else will be money down the drain if it grows.

What state are you in? Some of the current price volatility isn't a great basis for calculating your costs or savings. Replace all your incandescent bulbs with LEDs. Deal with the sucky parts of it later. For a typical 1,800 square foot home converting to LEDs can save you 2-3MWh/year. (For parts of the country with higher evening rates it is even greater economic savings.) Look at tightly zoned small ductless mini-split units rather than central AC-- at least one in the bedroom and likely one in the living room. Shut things off when you don't need them.

What is your total annual energy consumption? A 6.5kW system should offset about 9-10MWh/year.

 

[beowulf]

All good info. Man.. is there ANY LiFePO4 battery made in the USA (or Germany). I get worried crap out of China could be used crap and not last nearly as long as they say (e.g. 5000+ cycles at 80% DOD). Too often got used/reshipped crap. That's why I hate trying to buy from Alibaba or what not. To easily scammed and too hard to get money back.

So.. 48V for any sort of battery storage. Got it.

Had a kill a watt.. cant find it.. just ordered one.

I do have a full rack of IT network gear (Ubiquiti stuff) in my garage and run to our home network center (in closet upstairs) where I run a couple more things to connect to the networks of rooms. My PC is a gaming setup.. after I get that kill a watt I will have a better idea of how much it eats up under load. But these days.. you can build PCs pretty dang efficiently.. just run NVMe drives, a GPU.. m/b has everything you need. When I ran the PC on my cheap VATID portable 300w battery.. it showed it was using about 100w of power. When I ran a game.. that jumped to 250 or so.. I do have a AMD 6900XT GPU which I know can eat up some power too under load. So I'll have to test it under different loads.

What Battery bank (Yeti, Jackery, etc) is best.. I'd rather cry once buy once.. I don't want cheap crap but I do want longevity.. the ones that only charge 500 or so times.. no thanks.

I don't want to add to solar/inverters as we're likely moving sooner than later.. so whatever I do.. I want to take it with me. Hence was thinking the EVE batteries + portable power station setup.

Why 48v..anything else wasted? Can you elaborate so I have a bit more info on that.

I started to buy the 4ft LED bulbs to replace my garage halogen or.. gas ones.. forget what they are. Learned there are two types.. ones where you rewire the ballast and ones that dont need that. I prefer not to rewire it. I also have all these horribly expensive and hard to find push in lights.. started to replace some with compatible LEDs.. but kinda not liking the LEDs.. I've had a few burn out already.. and they claim 15 year life's.. so not sure if they are all just crap quality.. or if the only right way it to completely replace ballast/light fixture with new ones.. which will run a couple hundred per light to have someone do it. I also try to run 5v USB LED lamps on desks/etc instead of overhead ceiling lights.

 

[400bird]

All good info. Man.. is there ANY LiFePO4 battery made in the USA (or Germany).

Literally, no. All lifepo4 is made in China. You can probably find packs assembled elsewhere with cells from China.

I don't want to add to solar/inverters as we're likely moving sooner than later.. so whatever I do.. I want to take it with me. Hence was thinking the EVE batteries + portable power station setup.

You can unbolt inverters from the wall quicker than they install.

Why 48v..anything else wasted? Can you elaborate so I have a bit more info on that.

It's about upgradable. If you start with 12 volt and want to upgrade, most of the components will need to be replaced with 48 volts components in one expensive upgrade.
If you start at 48 volts, upgrades/increased capacity can be added one component at a time.

I started to buy the 4ft LED bulbs to replace my garage halogen or.. gas ones.. forget what they are. Learned there are two types.. ones where you rewire the ballast and ones that dont need that. I prefer not to rewire it. I also have all these horribly expensive and hard to find push in lights.. started to replace some with compatible LEDs.. but kinda not liking the LEDs.. I've had a few burn out already.. and they claim 15 year life's.. so not sure if they are all just crap quality.. or if the only right way it to completely replace ballast/light fixture with new ones.. which will run a couple hundred per light to have someone do it. I also try to run 5v USB LED lamps on desks/etc instead of overhead ceiling lights.

Energy savings is better than increasing production.

 

[Chuck E.]

Hello,
I'm new here but not in-experienced in electrical. My take on this whole conversation is that you first need to access your actual usage in power, how much your current solar is helping and the difference you need to make up. As mentioned earlier, if you have 6.5KW and your barely covering your AC usage I feel you still may have a long way to go to significantly reduce your power bill. You can do a little tracking on your electrical meter writing down the meter reading every day at exactly the same time (maybe 6PM or similar) this is kind of redundant to just using the KwH used on you electrical bill but I have found it's helpful to get a bigger picture of things like more usage over weekends etc. Essentially whatever your KwH usage per day is on your electric bill is how much you need to try to make. If your location has an average of 5 hours of solar per day (this includes rainy days, cloudy days and less than optimum days) and your looking to use 200 watts of panels then you will only make about 1 KwH per day (not a lot) on top of your 6.5KwH system, (which by the same math your 6.5 Kw system should make an average of around 26 KwH per day). I would also try to find out how much your 6.5Kw system actually does produce, it may give some insight into how well the system is working. Also, power reduction (hence Money paid to the electric company REDUCTION) should be approached from two fronts, one is reducing the consumption through efficiency (e.g. insulation, weather stripping, habits, windows, etc) and the other front is producing power that will augment your usage drawn from the power company. In closing, build for expandability (48Volt systems to start with isn't a bad idea vs 12v) because (DIY) solar is a journey not a destination, theres a lot of questions for you to answer/learn before you pull the trigger on very much equipment IMO.

Best of luck and be sure to enjoy the journey, I have.

 

[Shimmy]

Focus on incandescent lights that are heavily used; fluorescent bulbs are going to be less of a savings. Also, look at energy use for a whole day and not different operating modes. An alternative to a KillAWatt is going with something like a Sonoff S31 and flashing with Tasmota. You can link it with HomeAssistant or just treat it as individual devices.

FWIW, My "modest" network has 16 cameras, a USW-48-POE-Pro, UNVR, USW-16-150W, and a handful of USW-8-60Ws, plus 8 access points, ER-4, and a few NUCs running Proxmox and some other bits and bobs, and comes in under 400W / 7kWh/day

 

[50ShadesOfDirt]

As you are currently grid-connected, totally agree with the above "reduce existing loads by all conservation measures". With that done, next might be to determine your electricity costs/times ... does your utility charge more for peak hours, and less in off-peak hours? If so ...

If you are remotely handy at all, build a "portable" 24v system, hand-truck mounted:
- Battery bank of Ampere Time (while made in China, they are sold/serviced in the states; they may now have the name "LI Time" as well), mounted at base of hand-truck. I've used these (24v system) approaching two years now. Great company to do business with.
- All-in-one (MPP) mounted up high.
- small distribution panel, other bits & bobs (wiring, fuses, etc.)

And stop right there for now ... this is a separate system, usable for your home office needs. Portable for camping, or taking it with you if you move. Charge it with the grid during off-peak hours (charge at night when power is cheap(er), use during day). No solar, although it would be easy to add solar in the form of portable panels for camping use. If you do move, the system can be easily disassembled and turned into a full system (off-grid) somewhere else, or kept portable.

Power outage on grid side ... no problem (other than the inconvenience). Roll the hand-truck where needed, plug stuff in. Charge with an itty-bitty honda or similar inverter gen if outage lasts days.

Everything is heavy ... the hand-truck concept makes it light/mobile. Tons of youtube vids of hand-truck builds, plus Will's own vids describing 24v, aio, etc. (the components). Many other potential uses ...

The flexibility and ease of use of all these components have really made it easy to do just about anything you can think of ...

Hope this helps ...

 

[LydMekk]

Thinking ahead atleast go for 48 Volt based hardware and batteries.

 

[Shimmy]

If you are remotely handy at all, build a "portable" 24v system, hand-truck mounted:

I agree with everything except the 24V. I'd go 48V and likely just go for one of the server rack batteries. You have a limited investment at this point, so not the end of the world.