Why I Made the Switch: Upgrading Off-Grid Solar from 12V to 24V

[@powerguymark]

You've done a great job Marine 💪 The deep understanding you have gained of this stuff was indeed hard-earned. Now you're able to share your knowledge in a very down-to-earth way. I wish you continued success in your KZbin channel in 2025. Thank you for your service.

[@TheOldJarhead]

Thank you sir! And I wish you a happy and prosperous 2025!

[@neolithicnobody8184]

My latest portable build is 48v. Designed it that way deliberately to be capable of handling a welder, if needed. My best friend has lived in a camper for over 15 years now and is currently testing this latest build as his sole power source. So far, so good! 3 months in and no problems yet. He said it's like being plugged into the Grid, he can run everything at once and have no problem doing it. He's been Boondocking since Thanksgiving, something he hasn't tried in over 10 years. The last time he tried it, he had to resort to a generator to keep up by the 3rd day. He's hinted several times that he enjoys the Peace and Quiet over the noisy generator and that he dreads the day he has to return it to me. Looks like Build #6 will soon be in the works. lol

[@TheOldJarhead]

That's awesome! Sounds like a great setup.

[@SS-qk8oc]

How much to budget? Also, we would all love some details, as much as you're willing to share!

[@TheOldJarhead]

Agrees

[@bradlarson8458]

I just recently went through the same progression. Built two (2) parallel systems each containing: 12v, 2000w pure sine,800w solar, 40a controller and 1600ah battery. I was at my limit in adding solar due to amps. Was going to up to 24v but after pricing the new inverter and battery charger (could use my existing charge controller) it was going to cost about the same as buying an EG4 3000. So I reorganized my battery banks to 48v (with balancers) and rewired my solar panels from two strings into one to get my voltages up and amps down and put in the EG4. Only regret... wish I did it sooner. But like you, the equipment wasn't available and I was on a shoestring budget and was putting everything together piecemeal.

[@TheOldJarhead]

Nice. It's a journey, isn't it? 😁

[@johnsemrau6412]

Good Video 👍😊 I talked about my 12 volt system with you B4 but I'm planning on a 48 volt next I just wanted to stick with the 12 4 education 4 my self 👍

[@TheOldJarhead]

Thanks and understand

[@junkerzn7312]

I have a suggestion for the step-down. Use a small charge controller and a down-buffer battery. So, for example, a Victron 75/15 (yah, the smallest one they have) can easily take the 48V system bus voltage as an input and charge a 12V battery as the output. The charge controller only needs to trickle-charge the battery at no more than the (roughly) daily average wattage consumed by the 12V system, and the 12V LiFePO4 battery handles the actual loads. Close to zero stress on the electronics. So: 48V system bus -> 15A or 20A DC breaker or fuse -> Victron 75/15 -> 12.8V LiFePO4 battery -> (output to 12V devices via fuses or breakers, etc). Program the charge controller for 10-12A and forget about it. It will get warm, that's it. Then choose *any* 12.8V LiFepO4 battery for the 12V side depending on the amperage(s) you need to support. (I mostly use little 20Ah or 30Ah 12.8V batteries myself because I don't have any large pieces of 12V equipment to run, but you can use any size battery). I do this all the time for step-downs. 48V->12V, 24V->12V, and 48V->24V. I like this solution far better than using a DC-DC because there is no chance of 48V getting on the 12V bus and destroying equipment, and I can use low-power electronics (e.g. 10A) and still support 100A loads on the 12V system bus if I need to using a 100Ah 12.8V battery. -- For safety the input to the charge controller must be fused and/or breaker'd just in case the MPPT clamps the input. The charge controller itself will be more efficient than a DC-DC because the circuitry is higher-quality and also only has a lightly regulated output (it has a battery to push against). That said, going 4x on the voltage (48->12 or 12->48) will never have extreme levels of efficiency. You should still get fairly good 95% efficiency out of the charge controller, though. It will be better efficiency than a DC-DC can do (usually closer to 90% for that kind of voltage differential). -Matt

[@TheOldJarhead]

That's an awesome idea

[@YouLookinAtMe-Bro]

How can you not make videos and have more subscribers? You ALWAYS have great info and are so knowledgeable.

[@junkerzn7312]

@@YouLookinAtMe-Bro I've considered it but it isn't really my vocation. Spending hours editing videos is not my thing (and I'm kinda a perfectionist so... probably not the best combination). I really enjoy commenting in good channels, though, in-between my real work (as an electrical engineer and programmer). Maybe if I were younger... Even this account was never meant to be my primary commenting account (else I'd use a take off of my name), and nobody gets the decades-old Sci-Fi reference. It just turned out that way. But I do like my privacy, hence why this particular account is otherwise empty. -Matt

[@TheOldJarhead]

It takes time. The more who watch them and comment, like, share etc the more sub 😀

[@TheOldJarhead]

Ahh, yes, I'm 59, but I am slowly learning. it takes a lot of work, but I'm retired, so it's a good hobby for me

[@robert4027]

thanks for the video i been rockin. 1200 watt 12v system 3 years now. . 2. of these victron 100/50 smart charge controllers. feeding the same 12v 300ah lifpo4 battery. 600 watts of solor going into each charge controller. this year thanks to black Friday deals. I'm jumping up to 24 v system. however the 12 v setup i have is flawless. never had any issues with it

[@TheOldJarhead]

Sounds like a great setup, but 24v is definitely the way to go!

[@casemodder89]

actually 48V is the real deal. but all depends on the size of the system. you can tricklecharge a remotely stored car battery on a 12V system (obviously). you can run a small cabin on 12V if you cook off gas and do laundry in a river. you'd need 24V to build a system that could power some tools. also the lowest voltage stage for a proper AC mini grid. and you'd choose 48V if you need to run a whole homestaed with all kinds of appliances off grid. there is no one-fits-all solution. the beauty of victron mppt chargers is that they support more then a single voltage stage. you can get versions that run 12/24/48V systems. so you could double or quadruple the power when upgrading from a 12V to 24bor 48V system while still using the same mppt charger and wires to the solararray and battery system.

[@TheOldJarhead]

It also comes down to today vs yesterday. Unless you were rich, no one was building 48v when I was building 12v. Today it's the most common and it's what I'd do if I were starting from scratch.

[@TheOldJarhead]

as you say, it kinda depends. He's running a pretty small system and 24v will work nicely for him since he's also going from 12v to 24v -- I won't argue that 48v has many advantages but if the expense is higher and the system is smaller, 24v works very nicely.

[@blazinggazelle6957]

Nice video. You have a sound plan for your future system. Good luck.

[@TheOldJarhead]

Thanks

[@TN-Mountain-Life]

Great info and advice! Thanks!

[@TheOldJarhead]

Thank you!

[@sojourner57]

Good advice. Hope your hand gets better soon...

[@TheOldJarhead]

Thank you!

[@weitang1196]

I'm also planning on 24v, as 48v is too expensive. I have four 100w Renogy solar panels and will get an MPPT controller this year. I may need to get a bigger MPPT, but for a 2s2p, 100v should be good enough if I want to expand the panels later. In case anyone is asking what I'm going to power. A backup fridge and outdoor light. 400W panels may look low for now; I'm sure I will add more if I can get cheap second-hand panels.

[@TheOldJarhead]

Good start

[@steverturnsk6190]

i am changing from 12 volt to 24 volt too. The main expense that I have are the inverters. I have a 120 volt inverter on 3/4 of the circuits of my house 100% of the time. I have a 240 volt Aims 4,000 watt inverter plugged into the generator recepticle (goes to the transfer switch in the main panel) for most of the time to the rest of the property, and I use grid power maybe for 1/2 kwhr average per day. I will have to buy two more 24 volt inverters, around $2,200. I will drop a slow start 1/2 hp pump down into the well and I am pretty sure that the Aims inverter is too small. With the sun on the solar panels I can use the bench grinders, cut off saws, drill presses with ease, all 1/3 hp motors. When I try to start a 1/2 hp bench grinder, sometimes the inverter shuts down on overload.

[@TheOldJarhead]

Must be drawing a lot of power!

[@MUNDODOHARDWARE]

Opa! vídeo top eu comecei com 24v off-grid e hoje uso 48v híbrido e existe um INVERSOR Deye de 50kw que trabalha com banco de baterias com tensão 650v e mais um pouco ainda. E várias pessoas ja usam em sistemas híbridos

[@TheOldJarhead]

Nice!

[@YeOldeTraveller]

I think 48V will be the norm for some time, Two reasons: 1. Diminishing returns. 12 to 24 and 24 to 48 were each a doubling which reduced the current by half with all the benefits you get from that. 48 to 60 will be only 25%, so not as dramatic. 2. Code definition of Low Voltage. The NEC defines Low Voltage as a nominal voltage less than 50V. This at least was the case when I designed my backup system. The rules change significantly when your nominal voltage goes above 50V. There needs to be a significant reason to do the extra work to comply, or change the limits. I don't think there is enough benefit at 60V. I think the next jump for DC system voltages will be to 120V. All the rules for DC already apply, and design requirements are basically the same as household AC. It simplifies many of the conversions, and you get the benefit of smaller conductors. This is the point where I think there is enough benefit to change the base design. Thanks for the video explaining what you did, why, and what you would do today. Always good to see real systems built my real people. Semper Fi

[@TheOldJarhead]

All great points though most are over low voltage today with 48v systems

[@YeOldeTraveller]

@@TheOldJarhead True, and that was the case for my AGM based system. The key was the word 'nominal'. As long as it is considered a 48V 'nominal' system, the low voltage classification remains. So far, AFAICT, the current crop of Lithium based systems at ~51.2 is still considered Low Voltage. I expect, but have not looked, that there is a finding that 16s (4x 4s Li cells used like 12V Lead Acid) are considered to be 48V nominal for the purposes of the NEC. As always, your inspector will have the final say.

[@TheOldJarhead]

Systems yes, but arrays, no. A 109+v array is considered high voltage

[@YeOldeTraveller]

Agreed, but arrays are literally all over the map from 12V to over 600V depending on implementation.

[@TheOldJarhead]

I guess technically I'm wrong. You see in Telecom 'low voltage' refers to 48v nominal systems as you state. However, OSHA says it's 50-600v. Now this is interesting as someone who worked in 'low voltage' in telecom we knew that anything above 48v nominal needed an electrician but I guess, while that may be true, an array of 500V is still considered 'low voltage' by OSHA. So it's a gray area in solar I guess. Though they may argue that you need a certified electrician to work on anything above 50V.

[@andrievbastichy8551]

nice video. 👍

[@TheOldJarhead]

Thanks

[@anandrew6641]

👍👍👍

[@TheOldJarhead]

😁🤙👍

[@Not_Sure_]

Why not set it up as a 48V system ?

[@TheOldJarhead]

I thought I mentioned that, but in 2017, 48v wasn't that common, whereas everyone was doing 24v, and it was cheaper. At the end of the video I tell you what I would do today

[@koskos758]

Next step 48V - you are welcome.

[@TheOldJarhead]

You'll love it

[@Firephosure]

Nah, I always recommend people 24v to start. 48v is nice but there is limitation and the biggest one as you mentioned is needing around ~60v from your panels to charge. 24v is a nice middle ground.

[@TheOldJarhead]

Yes, true. Though easy to get that voltage today. Heck, I'm testing a 400w foldable panel that runs 38v

[@kenputt1750]

I have 8 24v 200amp panels hooked in series/ paralel ,48v runs around 72 v and 12.5- 13.5 amps, they charge 6 mega2 oupes batteries, no sun plug them in. No sun for over 3 days and no grid, I have 2 - 48v metal case batteries that are 5060 a/h to charge the Oupes power station.

[@TheOldJarhead]

Nice

[@DANG--]

[@TheOldJarhead]

🤙

[@paulandgrizzly]

I live in a camper and built a 12volt solar system. Got myself 2 300ah 12volt lfp batteries, 6 450watt 36volt panels, 2 mppt solar charge controllers and a 4000watt pure sinewave inverter. Works great but the wires get hot during the summer maxing out the charge controllers. Will be buying 2 more batteries to switch to 24volts

[@TheOldJarhead]

You'll be happy you did go 24v 😀

[@paulandgrizzly]

@TheOldJarhead after spending all this money to find out 24 volt is cheaper and more efficient ya ill be way happier and will tell everyone not to make the same mistake lol

[@TheOldJarhead]

Components aren't cheaper but wiring is as well as breakers etc but 12v is cheaper in some ways

[@kenputt1750]

If your going to switch , go right to 48v or 96 volt, cool wires more possibilities.

[@TheOldJarhead]

I do think 48v is the way to go today

[@dustydawson8977]

Long learning curve, more expensive in the long run. I did my research first, started with 24v system, and it's actually just as cheap as 12v,way more efficient, and much safer. Yes I'd do 48v or higher if I ever change. Truth, 12v no, pwm no, high frequency no, and it might be more expensive, but micro inverters are the truth, and being able to Island yourself with Enphase 8 micro inverters, is state of the art. The only company that can grid tie and Island themselves when the grid goes down, that has always been impossible by code.

[@TheOldJarhead]

Thanks. Since I don't grid tie (and no plans to) that's good info. The less expensive part of 24v is the wiring.

[@dustydawson8977]

Not what I was intending, but I'm grid tied in my home, not off grid, and no electric bill with a 5kw system, house is all electric 2600sq ft. But I have 2 / 30amp120v solar generators, 24v/10kw in lithium, both low frequency, with dual mppts in each one, with 13.8v 20 amp outputs also in each one, and that was my first purchases 10 yrs ago. But hey, maybe I'm just stupid and don't know shit

[@TheOldJarhead]

Strange response -- I did say that was good information to share and that I don't grid tie -- I suspect you know a lot. Grid tie is beyond my knowledge base as it's not something I'm interested in. For me it's about off grid, in the woods, in a small cabin ;) Cheers!