More 12v vs 24v system discussion

[Diemjoe]

Hi,
I am in experiment mode on a small 12x16 shed that I have set up very minimal electrical usage in preparation for a total off-grid 600sf cabin. It has 12v USB charging ports, lights and a small 12v Cosco fridge. There are a couple rarely used 120 AC outlets. I have 2 12v Lead Acid batteries approaching end of life running in Serial with a 24v Inv/Mppt Charger. I have a 24V to 12V 30A/360W converter. Everything works fine.
My question has always been the value of 24v or 48v setup compared to 12v. The answer I usually get is the thinner wire needed. But given the stepdown converter is usually near the battery, it's still 12v running to the rest of the loads. 24v capable loads are usually more expensive than 12v and harder to find.
I spoke to a service rep at ShopSolarKits and he did add that on the Solar Panel side higher voltage systems can accept more panels. Which is the real reason why I will move forward with 24v battery banks, (that and I already have the LV2424 MPPSolar hybrid).
My solution is to run 12v batteries in Series with the reasoning being that if I ever lose the MPPSolar, I can swap everything around and use and old 12v MPPT I have in storage to keep things running while I wait for repairs.
Not really a question rather than maybe a point of discussion. Thanks for any input and comments.

 

[Doggydogworld]

I think you're right about wiring. The main advantage of 24V seems to be twice the MPPT/Inverter power throughput for only a little more money. Even more so with PWM, most support both 12 and 24V so you can double your charging power with the same controller.

 

[Checkthisout]

Im running 24 now because I got a good deal on 24V multiplus but 48V is best.

Yes smaller wire but also your options for server rack batteries are better. Your BMS is also cheaper. Consider that you might need a 200 AMP bms for a 24 volt system or 400 for a 12V.

With 48V you only need 100 amps etc....

with 12 volts you need no converters to make 12v stuff work. With both 24 and 48 volt you do. This means the 24 and 48 volt both have that cost but your 48Volt system will have cheaper wire and a cheaper BMS.

I would argue 24 volts is defunct unless you have a vehicle with a 24volt electrical system you're going to put a solar system in.

 

[Diemjoe]

Im running 24 now because I got a good deal on 24V multiplus but 48V is best.

Yes smaller wire but also your options for server rack batteries are better. Your BMS is also cheaper. Consider that you might need a 200 AMP bms for a 24 volt system or 400 for a 12V.

With 48V you only need 100 amps etc....

with 12 volts you need no converters to make 12v stuff work. With both 24 and 48 volt you do. This means the 24 and 48 volt both have that cost but your 48Volt system will have cheaper wire and a cheaper BMS.

I would argue 24 volts is defunct unless you have a vehicle with a 24volt electrical system you're going to put a solar system in.

I hope you are wrong about 24v or it is still has some years left in it. I have too much invested in 24v. The cost of keeping up with technology I guess. Thanks for the input.

 

[AmyG]

I would argue 24 volts is defunct unless you have a vehicle with a 24volt electrical system you're going to put a solar system in.

I think it really depends on your system and situation. If I were designing a system for the OP's situation (shed/small cabin with mostly DC loads) I would choose 24V.

In addition to allowing you more PV input and having smaller cables to make set up in a small space easier compared to 12V, 24V allows you to have quick charge USB-A and USB-C ports so no more wall warts and running an inverter to charge laptops and phones. For me that's huge. I have also found 24V components and appliances easy to find and not more expensive (Dometic fridge, LED lights, water pump) and many will run on either 24V or 12V. In addition, some 12V appliances (MaxxAir fan, cellular router) work better on a buck converter rather than running off system voltage because they don't like the higher voltages that happen during charging.

If I were building a system for a larger cabin that was going to run most appliances off of AC power with an inverter on all the time I would certainly look first at 48V, but I think there are many situations in which 24V is still a great option.

 

[Checkthisout]

I hope you are wrong about 24v or it is still has some years left in it. I have too much invested in 24v. The cost of keeping up with technology I guess. Thanks for the input.

You're not going to have any issues with support. I don't mean obsolete. I just mean it probably provides the worst value of the 3 voltages for the reasons I listed.

 

[Checkthisout]

I think it really depends on your system and situation. If I were designing a system for the OP's situation (shed/small cabin with mostly DC loads) I would choose 24V.

In addition to allowing you more PV input and having smaller cables to make set up in a small space easier compared to 12V, 24V allows you to have quick charge USB-A and USB-C ports so no more wall warts and running an inverter to charge laptops and phones. For me that's huge. I have also found 24V components and appliances easy to find and not more expensive (Dometic fridge, LED lights, water pump) and many will run on either 24V or 12V. In addition, some 12V appliances (MaxxAir fan, cellular router) work better on a buck converter rather than running off system voltage because they don't like the higher voltages that happen during charging.

If I were building a system for a larger cabin that was going to run most appliances off of AC power with an inverter on all the time I would certainly look first at 48V, but I think there are many situations in which 24V is still a great option.

Keeping this in mind, if both the 24 and 48 system probably need a buck somewhere, why not go with the 48V and get even smaller wiring, more watts out of your charge controller, more options for batteries, cheaper BMS etc?

That's my logic.

With 12V everything just becomes standard RV stuff without the need for the buck converter.