48V vs 24V Advice Needed

[RicoPobre]

I’ve read other discussions on this and the consensus seems to be that 24V is acceptable but 48V is preferred. If you are going with inverters 3000 watts or higher than 48V is the way to go because wire sizes become an issue. Going with 48V also means you need to pay more heed to safety issues with the higher voltages and make sure your switches and fuses can handle the much higher voltage.

Even after reading all of the advice, I am not sure whether to go 24V or 48V but I’m leaning to 24V. I have previously put in a 400 watt system with a 200 AH lithium battery pack in an RV. It works great. I recently bought off grid land in Arizona and I need to get a system in place. I’m currently living in a nearby town paying rent. I’m financing all of my improvements from work as I go. The sooner I get out of the apartment and on the land, the more money I will have for building improvements. With a family, money right now isn’t growing on trees.

I have 12 240 watt panels from San Tan Solar to set up. I don’t have batteries, charge controllers, or inverters yet. I’ve been waiting to buy them until I know what system I am going with.. I plan to buy more panels from Santan In the near future.

Why am I leaning towards 24V?
InitI’ll battery cost for a minimal system is less and it’s cheaper to add battery capacity as I go.
24V MPPT controllers look to be cheaper
24V inverters are a little cheaper and more available
Building seperate systems to handle different power needs isn’t a lot more expensive
I can add components as I can afford it

All that said, I don’t want to be penny wise and pound foolish. If it’s going to be a given that sometime in the next 5 years, I’ll be upgrading to 48V then I really should price that in now. I don’t foresee myself having any single circuits larger than 15 amp. I lived for three years in Baja on two single 15 amp circuits. 2 2000 watt inverters should suffice and I’d like to have them on separate battery banks and even solar systems So a failure in any single component doesn’t shut me down.

So in my situation, what would you all advise?

 

[DThames]

I have a 24v battery bank and 2x3000w inverters (split phase) but I don't plan to run them at 3000w very often, if ever. Right now I have 2 old BYD batteries on one 100amp BMS. A second 100amp BMS on a 280ah Eve setup (parallel to the inverters). I would need more current (3rd BMS) to really max out those two inverters. I give you these numbers as reference. I feel I am at the max of what I would want to do with 24v.

 

[jasonhc73]

If it is a mobile setup, 24v is fine. If it's a big Class A coach, 48V.

If it is your house, 48v.

 

[RicoPobre]

I have a 24v battery bank and 2x3000w inverters (split phase) but I don't plan to run them at 3000w very often, if ever. Right now I have 2 old BYD batteries on one 100amp BMS. A second 100amp BMS on a 280ah Eve setup (parallel to the inverters). I would need more current (3rd BMS) to really max out those two inverters. I give you these numbers as reference. I feel I am at the max of what I would want to do with 24v.

Thanks, that's the type of anecdotes I'm looking for. What do you plan to do when you max out your system? Build an additional 24V system to take pressure off your current one or convert over to 48V?

 

[MichaelK]

I would base system voltage on the size of the loads you plan on running. As a general rule of thumb this is the scale I would use.

1-1000W use 12V
1000-2000W use 24V
>2000W use 48V

Alternatively, you may want to parallel multiple 24V inverters to reach the power levels of a 48V system. This is my 24V inverter, and it's designed to run in parallel with a communications cable linking them so their power is phase-locked. So, two if these inverters working in parallel could outperform my 48V inverter.

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[rmaddy]

So in my situation, what would you all advise?

Another consideration is the amount of solar. 12 panels at 240W is 2,880W. At 24V system voltage you need a charge controller that can handle 120A output to the battery. At 48V it only needs to handle 60A. High amps SCC are expensive or you need multiple smaller ones. And you stated you plan to add more solar.

You might want to head over to the "Residential Solar" section of this forum. That may be a better place to ask questions like this.

BTW - I like the duality of your username.

 

[RicoPobre]

Another consideration is the amount of solar. 12 panels at 240W is 2,880W. At 24V system voltage you need a charge controller that can handle 120A output to the battery. At 48V it only needs to handle 60A. High amps SCC are expensive or you need multiple smaller ones. And you stated you plan to add more solar.

You might want to head over to the "Residential Solar" section of this forum. That may be a better place to ask questions like this.

BTW - I like the duality of your username.

Thanks! I had planned on multiple SCC and even separating the system into two if needed. A 60 amp SCC is priced ok for 24 volts but it seems like the 48V ones are more expensive because they are less available. Maybe it is just my biases?

 

[DThames]

Thanks, that's the type of anecdotes I'm looking for. What do you plan to do when you max out your system? Build an additional 24V system to take pressure off your current one or convert over to 48V?

My system is for stand by emergency power and for load shifting, if I want to burn a lot of power, say running the AC in the garage/shop. So, I don't expect to need a higher power level. Converting to 48v would be a bit expensive at this stage for me. I may however add more battery if a good deal comes along.

 

[RicoPobre]

I would base system voltage on the size of the loads you plan on running. As a general rule of thumb this is the scale I would use.

1-1000W use 12V
1000-2000W use 24V
>2000W use 48V

Alternatively, you may want to parallel multiple 24V inverters to reach the power levels of a 48V system. This is my 24V inverter, and it's designed to run in parallel with a communications cable linking them so their power is phase-locked. So, two if these inverters working in parallel could outperform my 48V inverter.

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Free Shipping! Schneider Electric Conext SW4024-120/240 Inverter/Charger, 4000W, 120/240VAC, 50/60Hz, 30A Transfer, 24VDC, 90A Charger, RNW8654024

ressupply.com

I am kind of basing my decisions off of those rule of thumbs. I know there are some cheap pure sine wave inverters out there for 24V 2000W and the price goes up quite a bit for either durability/quality or watts. The idea of losing my only 4000 watt inverter sounds a lot worse than losing one of my two 2000 watt inverters when a replacement can take a week even on Amazon.