Hi all Scotty here, I want to build a small portable system for the Enterprise, lots of free energy out here.

I want it to be around 3000 watts to start but want it to where I can add to it as desired, I want the system to have back ups in it so if something goes down I can patch it together and keep it going to a degree. I know very little about solar, I don't mind buying the good parts if they are worth it over buying the lesser. If I can get 2 lessers and have one for back up or just buy the good to start with. I have 10 thou watts worth of panels already that are 37 volts and 40 panels at 250 watts each I picked up used.. I don't mind spending the money to do it right. Any input from those who know would be great, so if you were doing this what would you do? Or maybe I have it all wrong? Thanks Scotty out...

Where is it going to be installed? Is this for a portable system, or something that would be residential? It this grid-tied, or just an off-grid setup? If it's grid-tied and going to be in a residence, you really start looking at potentially needing permits, UL-listed equipment, local regulations...

If it's residential, 3000W output is very low, unless it's designed to just do something like run some freezers in an outage. It wouldn't be sufficient for most people's whole-home needs, for example.

Basically, what does the system need to do, and where is it going?

I want it to be both, off grid. Need it to run a fridge ,fans, lights and a touch more is all but if I want to I can tie it in if I desire to the grid. Flexibility, I want it to be plug in and set it up where ever I want. I know nothing so correct me if i am wrong which is all the time. Here is what I was looking at, using Victron solar regulators. I want it to be so I can do 12 24 36 48 and have it to where the system is redundant. My thoughts are they are coming and who knows how much longer we will have power regularly here in the US so having a system to where you can add and subtract makes the most sense to me and power flexibility in how it is run and set up. Multiple smaller inverters? if one goes bad you can keep going? I would like one that can do 110 220 from 12 24 36 48? Thank you so much for taking the time to reply to me... Also I was looking at group 31 lead acid batteries?

Inverters only work with one battery voltage.

I would recommend starting with 1 48v server rack battery. It's a big financial hump for a test kit, but it will start you on the right path.

You really have to settle on one battery voltage. I think most people will tell you, myself included, it's smarter to just go with a 48v system in the current year. It will save money in the long run, and allow you to reach higher output wattage than you reasonably could with a 12v or 24v system.

To be clear, "grid-tied" specifically refers to systems that are integrated into the utility's grid and can export power back to the grid. You can plug in an off-grid system and use the grid to provide supplemental power to your loads or charge your batteries.

Moretorque said:

using Victron solar regulators. I want it to be so I can do 12 24 36 48

Click to expand...

I am assuming you mean a Victron MPPT charge controller. These list multiple voltages because they are designed to drop into systems that are 12/24/48v etc. The "system voltage" is referring to what voltage your battery bank is, and thus, what input voltage your inverter takes.

As @hwy17 said above, you basically have to pick one voltage, and I'd agree with him that 48v in the year 2024 makes the most sense for the most people if you're not in a specialized application like a car or boat setup.

Moretorque said:

have it to where the system is redundant. [...] if one goes bad you can keep going?

Click to expand...

There are options here- you can certainly build a system that is redundant, and some people do. Other people simply buy a second set of MPPTs/inverters and just keep them in cold storage. Some just buy critical parts like the controller boards, and keep those around.

There are inverters that can be set up in parallel and have closed-loop communication... There are a lot of options, it all depends on how much you want to spend and how much time to put into it.

Moretorque said:

Also I was looking at group 31 lead acid batteries?

Click to expand...

You might rethink this. LiFepo4 batteries will last way longer and provide more power and are close to the same price as lead acid.

Thank you all so much, I would like the system to do 12 and 48 so it can do marine and auto but 48 for the main solar with inverters. What about my 37 volt panels, will it work 48? This may be wrong but I had a guy tell me who has been doing solar for 50 years say the old panels from like the 80's and 90's last way way longer than the new panels. He told me he has panels that are 40 years old and still put out 80% and he said way more good materials were used back then? Are Victron good and should I go one or get several of them and wire them together. Yaa so get a good 48 inverter and buy a 12 as well? I do not mind spending the money up front to do it right the first time so what would you all do? Where can I get good deals on more good panels. I bought the ones I have years ago from San Tan Thanks a million...

RussNM said:

You might rethink this. LiFepo4 batteries will last way longer and provide more power and are close to the same price as lead acid.

Click to expand...

I can get group 31 Lead Acid new for 100 and they will work in my trucks as well... just guessing...

If you're wanting to feed 12v appliances with a 48v system, your options are typically going to be either a regular line voltage power supply to convert 120v to 12v, or I assume there are 48v to 12v buck converters. Not really my area of expertise.

The battery and inverter side of the solar system (typically what people would call the system voltage) can't be mixed and matched like I think you're imagining.

The "solar side" of the system, i.e. the voltage coming off your solar panels going to the MPPT will depend on how you configure the panels in series and parallel. How they're wired must fall within what your MPPT and PV wiring can support. It's likely to range from 100v up into the several hundreds of volts depending on the parameters of the MPPT unit.

TRUE deep cycle FLA batteries? something to check on. If you cycle them infrequently they might give you 3yrs maybe? But thats with lots of tender loving care. There are lots of guys on here who like lead acid and I started out with FLA. I traded that whole mess in for lifepo4 and its one of the better decisions Ive made. I no longer have to run batteries thru an equalization cycle, check electrolyte levels or specific gravity. Just letting you know what a lot of us have been thru along out path with solar. Its up to you to make the same mistakes and learn thru them. Thats how we learn right?

RussNM said:

TRUE deep cycle FLA batteries? something to check on. If you cycle them infrequently they might give you 3yrs maybe? But thats with lots of tender loving care. There are lots of guys on here who like lead acid and I started out with FLA. I traded that whole mess in for lifepo4 and its one of the better decisions Ive made. I no longer have to run batteries thru an equalization cycle, check electrolyte levels or specific gravity. Just letting you know what a lot of us have been thru along out path with solar. Its up to you to make the same mistakes and learn thru them. Thats how we learn right?

Click to expand...

Yeah, I gather most people on the forum will tell you that unless there is a specific requirement that dictates you need a particular battery chemistry like FLA or AGM, you would be better off going LiFePO4.

I can't imagine building a general use home system on FLA over LiFePO4. You're talking about being able to discharge LiFePO4 down to 20% SoC every single day and still getting a decade or more out of them. My understanding is even true deep-cycle FLA would get hosed in a short period of time cycling them like that.

I have no problem not using LA Group 31 batteries but they are interchangeable with trucks and cars is all, you just don't know the situation you may run into where you wish you had more auto batteries is all. I can get Victrons small ones that will do 48 volts. How does using several of these compare to one big one.. Would a group of these be a good set up start or would something else be better. What about the new solar tiles... Thanks....Both of you! I can spend the money just want to do it right once is all....

Moretorque said:

can spend the money just want to do it right once is all....

Click to expand...

Just keep on reading here about the pluss and minuses of the two types of batteries. Hopefully youll come to the right conclusion. I see absolutely no reason to have fla over lifepo4 other than temperature or not having a relatively warm spot for them. If you got the $ then........

RussNM said:

Just keep on reading here about the pluss and minuses of the two types of batteries. Hopefully youll come to the right conclusion. I see absolutely no reason to have fla over lifepo4 other than temperature or not having a relatively warm spot for them. If you got the $ then........

Click to expand...

I know that because you say so so I will by the Lifepoo4 batteries but I will have a 12 volt something or another as well for RV,truck. I want to get this stuff now so I am looking for a shopping list on what to get. Roll up style panels would be nice, does anybody make a panel you can roll up like carpeting? I just found them, are these type panels any good and they are only 12 volt?

Moretorque said:

I know that because you say so so I will by the Lifepoo4 batteries but I will have a 12 volt something or another as well for RV,truck. I want to get this stuff now so I am looking for a shopping list on what to get. Roll up style panels would be nice, does anybody make a panel you can roll up like carpeting? I just found them, are these type panels any good and they are only 12 volt?

Click to expand...

You can buy 12, 24, or 48v LiFePO4 batteries. I think the takeaway should be that if you need to power 12v appliances for some kind of mobile application, you should probably just build a 12v system. If you want to power standard 120v or 240v household appliances, you are really better off just going with a 48v system. If you want a mix of both, powering 12v appliances directly off DC current, and also running an inverter for 120v applications, 12v might make sense. But it's going to cost a lot to get wire capable of handling the amps you need to run a 3kW inverter safely. And I'm not aware of a 12v AIO that has a 3kW+ inverter. Most are more like 1kW.

You can easily buy a 48v AIO system that has 1 or more MPPT inputs and an inverter that can go 6kW and up.

If your goal is "I want an apocalypse system that I can loot car batteries to run my system with," well, I guess 12v makes sense there.

Moretorque said:

Roll up style panels would be nice, does anybody make a panel you can roll up like carpeting? I just found them, are these type panels any good and they are only 12 volt?

Click to expand...

I think most people will tell you flexible panels are not very good. I've seen a lot of reports on here that the durability and efficiency are crap compared to many traditional panels you can buy.

If portable, maybe an AIO would be more compact and neater. My fixed installation is all big heavy components with lots of conduit.
Some are 48V, but some are 24V, maybe some 12V. Could make more sense for light weight to move around.
PV panels will be bulky and heavy.

Multiple lower voltage panels can be connected in series. Most say up to 600V or up to 1000V, maybe some small ones do not.

How many times do you want to cycle the battery before disposing of it?
AGM is dumb and simple. Might be good for 200 to 700 deep discharges depending on quality.
LiFePO4 is often lower purchase price these days and 3000 to 6000 cycles, so pretty much a no-brainer. But has some issues to understand (output current limited by BMS, can't charge below 32F/0C)

Starting 48V is fine, but you may find a low-cost AIO at lower voltage and not upgrade, keep as is and buy another bigger when desired. e.g. 12V might be ideal for small system on a vehicle.

Flexible panels are shorter lived. Silicon wafers on glass are better. You might want 100 to 200W for portability, otherwise 300W to 500W or so are best price.

A couple sources:





(note they don't like to ship a couple panels due to damage, maybe 10 on a pallet minimum. But the other stuff could be good.)

Here is what I found... Battery Hook Up has a 153 volt 27 KWH banks that are new but surplus. The big problem is probably limited warrnty and they WEIGH 500 POUNDS! They also have 24 volt which I can wire in series to get what I want. .. Also a place called AliExpress has new YMPEOEG batteries for $ 733 and these are claimed to be 10,000 KWH and 48 volts and they say they will do 8000 cycles and you get free shipping with a 10 year warranty. That sounds to good to be true but I have to wait for it till June and they appear to be dealing directly with China? All these are the 4LIFE....

Moretorque said:

.. .. Also a place called AliExpress has new YMPEOEG batteries for $ 733 and these are claimed to be 10,000 KWH and 48 volts and they say they will do 8000 cycles and you get free shipping with a 10 year warranty. That sounds to good to be true but I have to wait for it till June and they appear to be dealing directly with China? All these are the 4LIFE....

Click to expand...

Aliexpress is a market site that many Chinese companies and resellers (some non-legit) use to sell items. Understanding how to buy from it to minimize risk should be researched.

There are a few major issues using group 31 batteries.

First off if you want them to last more than 2 or 3 years you can never discharge them below 50%. So right off the bat you need to de-rate the amp hour rating.

Secondly the rated amp hours is over 20 hours and in most solar systems the discharge rate is significantly higher. You need to find the data sheet for the batteries in question and find the graph for discharge current vs capacity and then de-rate accordingly.

Thirdly many of the cheaper batteries don't even have published datasheets and if they do they don't actually live up to those numbers. Also they don't last very long. In RV applications most people I know end up replacing there batteries every 3 years. Also many of the cheaper batteries don't have removable vents and thus you can't top them up with distilled water.

Lead batteries also need temperature compensation or you will majorly under charge them in the winter.

You may also be into the maximum charging rate of the battery.

They need to be vented outside.

Lithium iron phosphate batteries are getting pretty cheap and have lifespans of 15-20 years.

Odd ball voltages are difficult to find charge controllers and inverters for. It's best to go with 48v unless your building really small systems that are under 3000watts. Even at the 3000watt point the high currents require stupidly big wires at 12v.

Wouldn't just getting these 4Life style batteries in 12 volt and just wire up a big 48 bank be good?

I like the idea of car style batteries for versatility, so I can use them in vehicles as well or integrate car batteries into the system from anywhere.

The 4life batteries don't go up and burn your house down like regular Lithium? This happened to a guy in town who was selling solar systems and one of the batteries he had went up.