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Is 48V good for an Apartment?

mgentile7

New Member
Joined
Apr 29, 2024
Messages
13
Location
Richardson, TX
I'm curious is 48V is the way to go for an apartment backup system. I live in an area susceptible to power outages. I would need to power up 2 Frig/freezers-Full size, 1-Microwave, 2-Portable AC Units, Mics Computers/Phones. If this a good recommendation, then getting an all-in-one unit is what I would be interested in. My next question then is 3000W or 5000W? Which is best for my needs. Thanks in advance for any guidance.
 
If you're trying to run all that I wouldn't even think of anything less than 48V.

For your inverter size you really need to look at your loads more closely.
"Portable AC Unit" - first off, those come in so many sizes that the power requirements of them vary a lot. Look at the nameplate. Also ask yourself, in a power outage, is AC REALLY necessary? It is a power hog, especially on startup.
Microwave - again look at the nameplate. If it is a large one, probably safe to assume 1200 watts or so.

As a (very) rough estimate, if you're wanting everything to run at once, those two (three?) things right there would easily push over 3000W, and we haven't even looked at fridge/freezer, etc.

Are you looking for battery only, or adding any solar? Being in an apartment I could see solar being severely limited or a no go at all. How long do you want to run for in a power outage scenario? This is where you really need an idea of your daily power usage from the things you want to run so you can size your battery appropriately. And of course, budget appropriately!

Then you get into how much do you want to DIY? Prebuilt batteries are fastest and easiest, but will cost more than DIY, but those can be fiddly at first (especially the first time around) and suck down a lot of time to build out (again, at least first time around).
 
@SparkyJJO already said almost all I wanted to say :)

However, one thing to add. Even if you decide to downsize your loads I'd recommend to go to the highest voltage practical. The limiting factor for you may be how much space you want your battery to take. If going the DIY route, what size cells can you get? I've spent ages hunting down good quality 100ah cells (I failed to find them, I eventually decided to upgrade to 200ah and finally 280ah). If 16S 280ah is too large, it may be a tough choice. 8S 280AH with known good quality cells, or 16S with potentially unknown quality ones?
 
I would stick with 48V for any sort of home power just because it can scale up if/when desired more easily, and keeps current lower (and thus wire and fuse size).

12V or 24V I would keep to only small systems that by nature would be more limited in size, or where 48V is just not going to be practical.
 
RULE #1 ! NEVER BUY ANYTHING TILL YOU HAVE A PLAN !!!

Sounds like everything you intend to run is 120V. I strongly suggest you get yourself a Kill-A-Watt meter you can plug our devices into to measure how many amps/watts you are pulling. See here: https://www.p3international.com/products/p4400.html Then add up the the power used to give you an idea of what you "need" then add 20% cause everyone is always short.

A High Frequency Inverter/Charger is perfectly suitable for electronics like computers etc, they will handle fridges & freezers (with a bit of effort) and that's good as it can save you some bucks. NOTE that if you are NOT going to have Solar Panels, there is little point in getting an AIO with Solar Controller(s). You will want the ability to use the 120V Wall plug to be able to provide Charging Capability for our battery system and preferably a Unit that can be programmed for Time of Use. Most regions have tiered billing where overnight power costs are lower than during the day, so being able to charge your batteries when Grid Power is cheapest is a WIN (for the pocket book especially). In fact, many are doing time-shifting by running off battery during Peak Power Cost times and charging when Grid power is cheapest.

How many watts & what voltage to use.
In general, we say, not to pull over 250A from a battery system.
12V X 250A = 3000W or 120V/25A These are 4S (4 in series cells) *2
24V X 250A = 6000W or 120V/50A These are 8S (8 cells in series)
48V X 250A = 12,000W or 120V/100A These are 16S (16 cells in series)
* uncorrected for efficiency & losses.
*2 The number of cells in a battery pack for the required voltage. This also affects the Size & Weight of each battery pack.
Battery Packs can be pretty heavy & large.
--- 24V Battery (8S) examples. X2 for 48V
24V/100AH weight avg 19-20kg (41-44lbs) 2560Wh or 2.5kWh
24V/280AH weight avg 44-50kg (98-110lbs) 7168Wh or 7.1kWh

A POINT THAT NEEDS TO BE MADE: I run my Offgrid Home on a 24V System. It runs my deep well pump and even my heavy equipment like Compressor & Even my MIG Welder and more. I have Very Rarely ever pulled more than 150A from my battery system (just the awful draw surge from Welder & Compressor when under load... ugh, it's fugly but no burps)

A final thought.
Life changes all the time, I would suggest rather than an AIO, so with a good quality Inverter/Charger with the Good features that is programmable & flexible to suit your needs. One that can be paralleled to increase capacity IF needed and hat can also interact with Solar Controllers etc should you ever move & need/want to add more capability... Not getting locked into a fixed system is wise, being able to add on and build out with reliable companonets is protecting that investment. Therefore I would very strongly suggest Victron Equipment which has an entire eco-system with all of their gear that works together & most reliably. It can all interact & communicate which allows you fne control & monitoring capabilities. This is Tier-1 Product, so it costs a bit more but you can easily count on 10+ years without issues and their support is EXCELLENT !

Hope it Helps, Good Luck.

A Quick Tip:
If you want to back up everything you are running. Grab your Power Bills, look at the 3 Heaviest Months of use. Most give you the kWh used per month and some even break it down to weekly & daily BUT you can do that yourself. Once you know what you are using per day in kWh then you have a baseline of your requirement. Most folks then add triple (in storage) that for emergency buffer (mostly rural homes etc) or more pending on situation & need. In a city with apartments I would say that 2X is more than enough in general. So if you use 5kWh per day, a 10kWh battery system will do it nicely. ALSO A BONUS with LFP: You can add batteries over time WITHOUT bad consequences. You CANNOT do that with Lead Acid, AGM etc, only Lithum Based batteries.
 
If you're trying to run all that I wouldn't even think of anything less than 48V.

For your inverter size you really need to look at your loads more closely.
"Portable AC Unit" - first off, those come in so many sizes that the power requirements of them vary a lot. Look at the nameplate. Also ask yourself, in a power outage, is AC REALLY necessary? It is a power hog, especially on startup.
Microwave - again look at the nameplate. If it is a large one, probably safe to assume 1200 watts or so.

As a (very) rough estimate, if you're wanting everything to run at once, those two (three?) things right there would easily push over 3000W, and we haven't even looked at fridge/freezer, etc.

Are you looking for battery only, or adding any solar? Being in an apartment I could see solar being severely limited or a no go at all. How long do you want to run for in a power outage scenario? This is where you really need an idea of your daily power usage from the things you want to run so you can size your battery appropriately. And of course, budget appropriately!

Then you get into how much do you want to DIY? Prebuilt batteries are fastest and easiest, but will cost more than DIY, but those can be fiddly at first (especially the first time around) and suck down a lot of time to build out (again, at least first time around).
Thanks for the reply !! Yes I need to do some research and math on possible appliances to run. To answer a few of your questions:
1-I would not see running everything at once. Rotate between heavy power us items. Probably run Frig/Freezers during the day and AC at night. It gets hot in Texas !!
2-I would anticipate a power outage of 3-7 days.
3-Yes, I would have solar panels attached to recharge. I live in Texas so lots of sun. I currently own 2-100W panels to charge my Licitti Battery Box w/ 12v 100AH battery. My apartment has a backyard space that gets lots of sun and I have a driveway that also gets a lot of sun.
4-I would anticipate purchasing an All-In-One unit like PowMR or SunPower 48V-3000m or 5000 W with 4-12v 100AH batteries.
5-Pricing is an issue but I'm aware of the need to buy quality items so I budget accordingly.
Please let me know your thoughts.
 
I would stick with 48V for any sort of home power just because it can scale up if/when desired more easily, and keeps current lower (and thus wire and fuse size).

12V or 24V I would keep to only small systems that by nature would be more limited in size, or where 48V is just not going to be practical.
Thanks for the reply and advice.
 
@SparkyJJO already said almost all I wanted to say :)

However, one thing to add. Even if you decide to downsize your loads I'd recommend to go to the highest voltage practical. The limiting factor for you may be how much space you want your battery to take. If going the DIY route, what size cells can you get? I've spent ages hunting down good quality 100ah cells (I failed to find them, I eventually decided to upgrade to 200ah and finally 280ah). If 16S 280ah is too large, it may be a tough choice. 8S 280AH with known good quality cells, or 16S with potentially unknown quality ones?
Thanks for the reply. Currently I have 2 powerqueen 12V-100AH batteries to build off of.
 
RULE #1 ! NEVER BUY ANYTHING TILL YOU HAVE A PLAN !!!

Sounds like everything you intend to run is 120V. I strongly suggest you get yourself a Kill-A-Watt meter you can plug our devices into to measure how many amps/watts you are pulling. See here: https://www.p3international.com/products/p4400.html Then add up the the power used to give you an idea of what you "need" then add 20% cause everyone is always short.

A High Frequency Inverter/Charger is perfectly suitable for electronics like computers etc, they will handle fridges & freezers (with a bit of effort) and that's good as it can save you some bucks. NOTE that if you are NOT going to have Solar Panels, there is little point in getting an AIO with Solar Controller(s). You will want the ability to use the 120V Wall plug to be able to provide Charging Capability for our battery system and preferably a Unit that can be programmed for Time of Use. Most regions have tiered billing where overnight power costs are lower than during the day, so being able to charge your batteries when Grid Power is cheapest is a WIN (for the pocket book especially). In fact, many are doing time-shifting by running off battery during Peak Power Cost times and charging when Grid power is cheapest.

How many watts & what voltage to use.
In general, we say, not to pull over 250A from a battery system.
12V X 250A = 3000W or 120V/25A These are 4S (4 in series cells) *2
24V X 250A = 6000W or 120V/50A These are 8S (8 cells in series)
48V X 250A = 12,000W or 120V/100A These are 16S (16 cells in series)
* uncorrected for efficiency & losses.
*2 The number of cells in a battery pack for the required voltage. This also affects the Size & Weight of each battery pack.
Battery Packs can be pretty heavy & large.
--- 24V Battery (8S) examples. X2 for 48V
24V/100AH weight avg 19-20kg (41-44lbs) 2560Wh or 2.5kWh
24V/280AH weight avg 44-50kg (98-110lbs) 7168Wh or 7.1kWh

A POINT THAT NEEDS TO BE MADE: I run my Offgrid Home on a 24V System. It runs my deep well pump and even my heavy equipment like Compressor & Even my MIG Welder and more. I have Very Rarely ever pulled more than 150A from my battery system (just the awful draw surge from Welder & Compressor when under load... ugh, it's fugly but no burps)

A final thought.
Life changes all the time, I would suggest rather than an AIO, so with a good quality Inverter/Charger with the Good features that is programmable & flexible to suit your needs. One that can be paralleled to increase capacity IF needed and hat can also interact with Solar Controllers etc should you ever move & need/want to add more capability... Not getting locked into a fixed system is wise, being able to add on and build out with reliable companonets is protecting that investment. Therefore I would very strongly suggest Victron Equipment which has an entire eco-system with all of their gear that works together & most reliably. It can all interact & communicate which allows you fne control & monitoring capabilities. This is Tier-1 Product, so it costs a bit more but you can easily count on 10+ years without issues and their support is EXCELLENT !

Hope it Helps, Good Luck.

A Quick Tip:
If you want to back up everything you are running. Grab your Power Bills, look at the 3 Heaviest Months of use. Most give you the kWh used per month and some even break it down to weekly & daily BUT you can do that yourself. Once you know what you are using per day in kWh then you have a baseline of your requirement. Most folks then add triple (in storage) that for emergency buffer (mostly rural homes etc) or more pending on situation & need. In a city with apartments I would say that 2X is more than enough in general. So if you use 5kWh per day, a 10kWh battery system will do it nicely. ALSO A BONUS with LFP: You can add batteries over time WITHOUT bad consequences. You CANNOT do that with Lead Acid, AGM etc, only Lithum Based batteries.
Thanks for the reply and advice. I am a fan of Victron. I have a MPPT from them for my Licitti Battery Box. I also currently have to LifePO4 batteries from powerqueen. I would build on that going forward. My intention is to build a portable station that could be rolled around my apartment as needed.
 
I might suggest you look at this thread where a really good portable system was built with a lot of thought & problems/quirks solved. It's a really well done portable setup with Good Oooommph.
 
Rule #0 might be to find out what the apartment rules & restrictions are, as you seem to be a tenant. As quietly as you can, find out what the owners/managers think about such things. If your solar gear burns down the apartment, or the entire block of apartments, things could get iffy in a hurry.

Given their response, an alternative might be a DIY solar generator (won't have a U/L listing on the assembly), or a purchased one (U/L listing very likely).

One advantage of the solar gens is that you can recharge them from the grid (the wall plug, after the grid is back up), giving you a brief coverage against short outages, and the system is mobile enough to use in other scenarios, like camping. Can also recharge at night, hopefully when power costs less.

Hope this helps ...
 
I would NOT want my tenants to have a DIY ESS due to the fire risk. If I found out about one I would give my tenant a Notice to Correct, and that IMO would be enforceable because of the code violation entailed by that system.

Yes, expensive electricity sucks, but the technology is not there to have fail-safe ESS, and the code reflects that.

I didn't know solar generators were UL listed. Do you have a reference?
 
Any US store-bought solar generator has a number of compliance marks, so it would take digging to figure out which marks each one has; Goal Zero, other big names. It's an appliance ...

My comments aren't meant to imply U/L 1741 (inverters hard-wired, AHJ & such), but it does mean that a store-bought appliance has a better chance of various compliance marks (U/L, ETL, CSA, etc.) than anything we could cobble together in a DIY solar gen. OP was advised of *the possibility* of diy or store-bought, *given* the rules & such of the apartment complex they are in.

Given apartment life, I'd say one or more compliance marks on an appliance would go a long ways towards CYA (OP's), if the apartment manager comes looking after "a fire" in an apartment. Homeowners rarely read the fine print of a grid agreement (and PUC agreement behind that) ... apartment dwellers rarely read the same fine print of a rental agreement. Usually, the details are in there, and a lot more scary stuff to boot.

With 100's of appliances in any given apartment, who knows which ones have compliance marks, which don't, and what the finger will point at, in the event of a fire ...
 
Rule #0 might be to find out what the apartment rules & restrictions are, as you seem to be a tenant. As quietly as you can, find out what the owners/managers think about such things. If your solar gear burns down the apartment, or the entire block of apartments, things could get iffy in a hurry.

Given their response, an alternative might be a DIY solar generator (won't have a U/L listing on the assembly), or a purchased one (U/L listing very likely).

One advantage of the solar gens is that you can recharge them from the grid (the wall plug, after the grid is back up), giving you a brief coverage against short outages, and the system is mobile enough to use in other scenarios, like camping. Can also recharge at night, hopefully when power costs less.

Hope this helps ...
Appreciate the thought. My complex frowns on anything to do with anything. Basically, they suck except for the maintenance crew. Those guys are awesome! I would not be connecting directly into the breaker box but rather connecting the appliances to my Solar set up directly.
 
I might suggest you look at this thread where a really good portable system was built with a lot of thought & problems/quirks solved. It's a really well done portable setup with Good Oooommph.
Thanks, I appreciate the lead.
 
Rule #0 might be to find out what the apartment rules & restrictions are, as you seem to be a tenant. As quietly as you can, find out what the owners/managers think about such things. If your solar gear burns down the apartment, or the entire block of apartments, things could get iffy in a hurry.

Given their response, an alternative might be a DIY solar generator (won't have a U/L listing on the assembly), or a purchased one (U/L listing very likely).

One advantage of the solar gens is that you can recharge them from the grid (the wall plug, after the grid is back up), giving you a brief coverage against short outages, and the system is mobile enough to use in other scenarios, like camping. Can also recharge at night, hopefully when power costs less.

Hope this helps ...
Yes, my apartment is very difficult to deal with. I have no intention to direct connect to the breaker box but rather have a mobile solar power station that can be recharged via apartment power when available.
 
Any US store-bought solar generator has a number of compliance marks, so it would take digging to figure out which marks each one has; Goal Zero, other big names. It's an appliance ...

My comments aren't meant to imply U/L 1741 (inverters hard-wired, AHJ & such), but it does mean that a store-bought appliance has a better chance of various compliance marks (U/L, ETL, CSA, etc.) than anything we could cobble together in a DIY solar gen. OP was advised of *the possibility* of diy or store-bought, *given* the rules & such of the apartment complex they are in.

Given apartment life, I'd say one or more compliance marks on an appliance would go a long ways towards CYA (OP's), if the apartment manager comes looking after "a fire" in an apartment. Homeowners rarely read the fine print of a grid agreement (and PUC agreement behind that) ... apartment dwellers rarely read the same fine print of a rental agreement. Usually, the details are in there, and a lot more scary stuff to boot.

With 100's of appliances in any given apartment, who knows which ones have compliance marks, which don't, and what the finger will point at, in the event of a fire ...
I may not have been clear in my initial comment. I am looking to build a portable solar charging station that will not direct connect to my apartment breaker box. I would only "plug in" to recharge the batteries as needed when the power is working correctly.
 
Will's hand truck build is a good place to start. If you have more budget though, or want more power output though, there's lots we can recommend over and above that.
 
I'm curious is 48V is the way to go for an apartment backup system. I live in an area susceptible to power outages. I would need to power up 2 Frig/freezers-Full size, 1-Microwave, 2-Portable AC Units, Mics Computers/Phones. If this a good recommendation, then getting an all-in-one unit is what I would be interested in. My next question then is 3000W or 5000W? Which is best for my needs. Thanks in advance for any guidance.
At those powers, yes. 48V or 400V.
 
Thanks for the reply !! Yes I need to do some research and math on possible appliances to run. To answer a few of your questions:
1-I would not see running everything at once. Rotate between heavy power us items. Probably run Frig/Freezers during the day and AC at night. It gets hot in Texas !!
2-I would anticipate a power outage of 3-7 days.
3-Yes, I would have solar panels attached to recharge. I live in Texas so lots of sun. I currently own 2-100W panels to charge my Licitti Battery Box w/ 12v 100AH battery. My apartment has a backyard space that gets lots of sun and I have a driveway that also gets a lot of sun.
4-I would anticipate purchasing an All-In-One unit like PowMR or SunPower 48V-3000m or 5000 W with 4-12v 100AH batteries.
5-Pricing is an issue but I'm aware of the need to buy quality items so I budget accordingly.
Please let me know your thoughts.
I don't think these loads can realistically be run off battery back up in an apartment. Four 12 volt 100 amp hour batteries will provide an insignificant amount of power for any heavy load, and 200 watts of panels would not be enough.

Realistically, I think you may be able to cook eggs with a 700 watt hot plate or run a crock pot to cook a day's worth of food when the sun is shining, and perhaps run a fan, but not the refrigerator 24 hours a day and air conditioning.

Since its getting hotter, you can get a kilawatt meter and plug this in to your devices and find how much power each device uses and come up with a plan. Put this on a spreadsheet and that will help you plan.

I am in a similar latitude in AZ, and with my solar generator with a 1200 wh battery bank, I can expect 400 watts of panels to provide me with 3 kWh of power throughout the day. I think you have 2400 wh of batteries and 200 watts of panels. To get so much power with my panels, I need to angle them into the sun three times a day.
 
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