What happened to the 24v DIY system web page?

Dzl

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For those using 100W panels, on a flat roof RV, 24V is far simpler than 48V… is it just too difficult to get the panels to output 48V reliably. Sure, placing higher wattage or higher voltage panels would remedy it, but the VAST majority of 100W panels are 17VMP… and in series would have a ton of shading on an rv roof… very difficult to get them outputting 65V…
Adding to this, Victron's recommended PV array configuration for maximum efficiency is:
For 12V batteries: 72 cells in series (2x 12V panel or 1x 24V panel in series).
For 24V batteries: 144 cells in series (4x 12V panel or 2x 24V panel in series).

Extrapolating from this, the recommendation for 48V for max efficiency would be 288 cells in series (8x 12V panel or 4x 24V panel in series) which would exceed what a common 150V or even possibly 200V charge controller is designed for. Now maybe this isn't a huge factor (this is Victron's recommended values, not their minimum acceptable values), especially for fixed installations where shade is non-existent or predictable, but it is certainly a consideration, considering that most brands small, medium, and budget charge controllers are 100V, 150V or 200V (Victron does also make 250V controllers, and some others make higher input voltage options, but not many that are geared towards mobile/marine).

*Epever also has similar recommended values from what I recall.
 

upnorthandpersonal

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Mostly because of my job where I'm over seas 6+ months at a time and my little cabin is unattended for upwards of a year in sub freezing temperatures for months on end.

Do you actually require power while you're away, or are they just in 'storage mode' at that time? If the latter, there's no issue with the temperature dropping. Research is showing that storing at freezing temperature slows calendar aging, so it's actually a good thing to store them cold.


And since you don't have a big self-discharge, they'll be good to go by the time it's warm.
 

Rednecktek

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Do you actually require power while you're away, or are they just in 'storage mode' at that time?
Yes.

More often than not I'm shoreside in January or Feb and get to head to the camp then. About half the time I've been able to spend up there has been sub freezing at least at night and just as often through the day. My last trip up was Valentines Day week of 2021, and Texas decided to share their love of cold. :)

I know the MPPT controller I'll have permanently turned on will have a little draw and with multiple frozen weeks in a row that'll destroy those nice expensive batteries. 😩
 

upnorthandpersonal

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I know the MPPT controller I'll have permanently turned on will have a little draw and with multiple frozen weeks in a row that'll destroy those nice expensive batteries.

The MPPT should only be 'on' when there is actual sun, no? The BMS will prevent charging at low temperatures, and discharging the battery in freezing temperatures is fine.
 

Rednecktek

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The MPPT should only be 'on' when there is actual sun, no? The BMS will prevent charging at low temperatures, and discharging the battery in freezing temperatures is fine.
Nope. If you go look at your MPPT controller at night it's still going to show voltages and wattage and the little icons showing battery and loads and such. Feeding that screen and calculating those numbers still draws power all night. Now, that may only be 1 or 2 watts, but after a day that's 24-48w, 7 days, 4 weeks, 4 months. Yeah, it adds up when your BMS hasn't gotten warm enough to take a charge that entire time.
 

Rednecktek

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Ok, mine doesn't. Which one do you use?
My PowMr's, my HQST, my EPEver, even the cheap PWM controllers always showed something on the screen all the time, even if it was only LED's on the PWM's. Are you using a Victron or something that has no screen? If so, I'm willing to lay money that there's either a remote monitor screen or a bluetooth transmitter that you can access when the sun isn't shining.

If your controller is completely dead at night, you've got something truly weird!
 

Steve_S

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I setup my system in 2015, 24V, anything Lithium then was "Ludicrous" in dollar terms back then, seriously and limited to what was available - it was Horrible ! So the choice left was Lead/AGM and such. 8x Rolls Surette S-550's (428AH Gross) was $3000, and these are 135Lb Heavies. Also at that time, Inverters, Inverter/Chargers etc cost a heck of a lot more & were not as plentiful and AIO's were a dream. 48V Inverter system cost a further Premium then as well. Had I gone 48V versus 24V back then my costs would have more than doubled.
$3000 for 428AH Lead (214AH useable) in 2015 gets you 300/400AH+ LFP in 2021
Also one must consider how much space 8 Lead versus 16 Lead batteries took up and the weight (for anyone mobile). This again has changed drastically since Lithium has become more "reasonable" (if it wasn't for the fricking shipping costs) 😡

Now in 2021
AIO's are plentiful. Costs have dropped SIGNIFICANTLY ! (for everything too) and the Availability of products & goods to support Solar / RE has multiplied faster than a Herd of Catholic Rabbits !
- Does 24V make sense today ? much less so than it did 5 or more years ago.
Hardware costs like AIO's & Inverter/Chargers are not that different between 24V/48V but with 48V you can go up to 12,000W (250A draw), so really you are just paying for the extra "Capability" and that difference isn't that bad.
- Future Proofing to be considered as well, makes sense to go with 48V that can also support EV Charging (from bike to car) with 220/240V-30/50A being quite possible from a 48V system... tomorrow comes and we never know what it will be.

My system is 24V/4000W LF and provides 120V which is fine for me as I have no need of 240VAC (all my AC systems (panels etc) can switch to 240 Mode very easily). IF I was Building TODAY, I would more than likely go with Victron (for premium) or Growatt (I would do this because I am frugal) and choose a 48 Volt / 240VAC Split Phase model capable of delivering at least 30A but preferably 50A.

My Midnite Classic-200 is showing 15V right now, it is Pitch Black out, not even moonlight OR starlight - it's totally overcast.
 
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BobR

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Yes indeed. I'll make a video about it. I just don't see much benefit to 24V. 12V if you absolutely need to. 48V for everything else. It's so easy to make a small 48V system these days, and it's cheaper and more efficient. And easier to build! I just don't see the point of 24V systems anymore. Would love for someone to prove me wrong on this.
Many boats have 24v DC systems.
 

BroomJM

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I took it down because those pages got the least amount of traffic. I think having so many options on the site can paralyze decision making. And personally, I hate when I have to build 24V. I just don't see the point. 48V is better.

Some things, like the trolling motor on my boat, run on 24v. I like having a dedicated 24v battery for it. Also, for a small backup system for home use, a 24v system is the "right size" for many folks. Just two batteries, the appropriate wiring, and a 24v inverter/charger is all you need.

Not everyone sees things the way you do because their needs are different. I, for one, really liked the 24v options you had listed and I'm pretty disappointed you took that information down. I know space on a web server is not free or infinite, but as you can tell from this thread, there were some folks who benefitted from those pages. It's totally your call, since this is all your stuff and not public domain, but keep in mind that each time you make a decision FOR someone else, like removing pages because you hate when you have to build a 24v system, is imposing your logic and reasoning on others. As someone who is providing a service to the public, it is better to acknowledge all needs and options, not just the ones you prefer.
 

chrisski

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I had a 12 volt system and when Iinstaled, I had the intent to upgrade to 24 or 48 volts in a year. A little better planning, I probably could have pulled off the 48 volt upgrade without completely gutting my system.

What stopped me from upgrading from 12 volt to 48 volts and opted on 24 volts is voltage rating of some of my components was 32 volts or 48 volts. Even though its labels 48 volts, charging could be up to 56 volts or 66 volts. I did not want to change out some Blue Sea Components I had:

This is pricey enough, and getting a higher voltage DC switch approved to a standard was hard:
46D0DEA8-5A38-4F45-AD8D-B11102BC5811.jpeg6A87EA8B-35EE-4453-8058-FECBFC01A292.jpeg
Another one I got, the Maxi Fuse and ANL fuses, had 32 volt max. I use these to protect the branches from the main busbar.
E13E8388-AA3F-44BD-96D1-28D217992317.jpeg20292803-462A-47B5-89F4-BBBA6EA2E93C.jpeg
D2281EFA-DED0-4A2D-AD8E-AD1840948482.jpegF7B9C4C5-A5EF-4227-A3C8-F2B036E83E6C.jpeg
The fuses good for a 48 volt system are Class T and except for equalization, MRBF. Not Mega, glass, or ATC blade.

THere’s other components, but mostly shows better planning would have been let the upgrade happen.
 

pda1

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I had a 12 volt system and when Iinstaled, I had the intent to upgrade to 24 or 48 volts in a year. A little better planning, I probably could have pulled off the 48 volt upgrade without completely gutting my system.

What stopped me from upgrading from 12 volt to 48 volts and opted on 24 volts is voltage rating of some of my components was 32 volts or 48 volts. Even though its labels 48 volts, charging could be up to 56 volts or 66 volts. I did not want to change out some Blue Sea Components I had:

This is pricey enough, and getting a higher voltage DC switch approved to a standard was hard:
View attachment 77090View attachment 77091
Another one I got, the Maxi Fuse and ANL fuses, had 32 volt max. I use these to protect the branches from the main busbar.
View attachment 77093View attachment 77092
View attachment 77094View attachment 77095
The fuses good for a 48 volt system are Class T and except for equalization, MRBF. Not Mega, glass, or ATC blade.

THere’s other components, but mostly shows better planning would have been let the upgrade happen.
 

rmaddy

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Oh, great. $4,500 later I find out 24v isn't the way to go.
There is absolutely nothing wrong with a 24V system. Does it meet your needs? Yes? Then perfect.

Would 48V be better? Maybe. It depends on many variables.

In my case 48V would not have been any benefit at all. Two years ago when I started buying stuff it wasn't really even a valid option. Even if I started today I wouldn't go with 48V. Again, for my needs it provides no benefit. I might save $20 on smaller battery/inverter wires. Maybe.

Merry Christmas on a rainy and poor solar day.
 

chrisski

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Oh, great. $4,500 later I find out 24v isn't the way to go.
I disagree with 48 volts being the way to go.

An RV build is one of them. 24 volts is good for 2000 watts - 3000 wattts of power, plenty for most builds. Also if you pan on using DC power, extremely hard to find 48 volt accessories, but you can find 24 volts, 12/24 volt dual accessories. I really would like to see a 48 volt fuse block. Only thing I found for fusing 48 volts is MBRF and Class T fuses. This would get pricey if you have 6 legs you’re sending power to.

If this were going from 48 volts to 120 VAC only like for a house, I completely understand 48 volts being better.
 

BroomJM

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Atomic Ed

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2X 24V batteries fit and provide 48V. I avoid using 12V packs in series when I can. Having 4X bms in a string seems illogical. The less parts, the better.

Ohhh you're using FLA's?? Ok I understand. If you are constrained to that battery box size and voltage, I get it. That's unfortunate.

Ok I'll put them back up.
Thank you. Your videos and site are very much appreciated and the 24v info is very helpful to us who use it.
 

alcook62

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I'm gonna throw my two cents in and add another vote for the adequacy of a 24v system. I'm off-grid completely and power my home with a 24v based solar setup. I have all the amenities a modern home typically has, and after three years I don't know that I would do anything different.
 

pda1

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I think you were being facetious, and rightfully so! :)

Will put the page back up because enough people expressed an interest in that information. It's what I'm basing my small emergency backup system on...basically just enough to run the fridge, freezer and a few lights.
No, I wasn't kidding but wish I were. Battle Born batteries (2) which I in no way regret purchasing cost $1,500, the panels (10- 225w panels) from ebay cost $880, MPPT, BMV-715, Victron Blue Smart Charger, Inverter, wire, circuit breakers, combiner box, rack system (Unistrut ground mount) bus bars, battery switch, fuses, Lugs, 24v water pump (low cost) well pump wire, etc.....

For goodness sake don't tell me I paid too much and that it should cost half of that.

Granted I'm only setting up 4 panels but once I've had some experience I'll expand to the full 10 panels.
 
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