Cube Truck Conversion

CubeTruck

New Member
Hey all! Getting a cube truck soon and im going to be converting it to a camper. aiming for 16ft box. considering chopping and extending the roof as well. Ive been researching solar systems and was almost set to buy a 1500w 12v system but the idea of 48v being better was nagging at me.

All I need in addition to everything a 12v system would have is a converter. So far it looks like im gonna save on the panels by going 48v. Wiring should be easier and more compact. I live in Canada so sourcing parts isnt as easy as it is in the states.

My main concern right now is batteries. Im gonna go LiFePo4 and I want about 400ah minimum to get myself started. Is it going to be significantly more expensive to do this with 48v vs 12v? Is the upfront cost going to be worth the lower amperage using appliances etc on a 48v system?
 

Short_Shot

Photon Sorcerer
48v isn't "better" inherently.

You'll save a bit on wiring and some of the components are a bit less due to lower current, however you might entirely offset that savings by needing a 48 to 12v buck converter to power standard accessories.

Rather than starting with power, let's start with the usage and figure out how much power you need first hey?

What do you need to run, want to run, and for how long?

You could also come visit the US to buy stuff👌
 

Rednecktek

Solar Enthusiast
The biggest advantage of going with a 48v system is the wiring. Feeding a 1500w inverter on 12v is a MUCH thicker wire than feeding a 1500w on 48v. HOWEVER Unless you're going to want a huge inverter there's no reason you couldn't stay with 12v. The fat wire involved is between your batteries and your inverter so since this is a van and there's not a lot of space I'm going to assume that your batteries are going to be pretty darn close. A foot of Fat/0 wire is really negligible, 25ft is Stupid$$$ Much cheaper and less hassle than getting a buck transformer involved.

Also, if you're going to be using Lith batteries and expect to charge them from the alternator you're going to need a DC-DC transformer involved to not fry the alternator or batteries.

As to the panels, whether you wire them up for 12v or 48v doesn't matter, your charge controller is there to take the Whatever-volts from the panel and convert them to the Whatever-volts of the batteries. The only concern with that is that some MPPT controllers will limit your panel wattage and VoC input based on your battery voltage, usually around the 700-800w for 12v, so that is a concern. The wattage of the panels themselves has nothing to do with the battery bank voltage, just how well you can use them.

Does that all make sense?
 

noenegdod

Solar Addict
Hey all! Getting a cube truck soon and im going to be converting it to a camper. aiming for 16ft box. considering chopping and extending the roof as well. Ive been researching solar systems and was almost set to buy a 1500w 12v system but the idea of 48v being better was nagging at me.

All I need in addition to everything a 12v system would have is a converter. So far it looks like im gonna save on the panels by going 48v. Wiring should be easier and more compact. I live in Canada so sourcing parts isnt as easy as it is in the states.

My main concern right now is batteries. Im gonna go LiFePo4 and I want about 400ah minimum to get myself started. Is it going to be significantly more expensive to do this with 48v vs 12v? Is the upfront cost going to be worth the lower amperage using appliances etc on a 48v system?
400 ah @ 48 volts is 4x as much battery as 400ah @ 12v so in that context, yes, it is a lot more money to get started. If you needed 400 ah @ 12 v you can do 100 ah @ 48v.
 

smoothJoey

SmooJo
Im gonna go LiFePo4 and I want about 400ah minimum to get myself started.
400 amp hours at 12.8 volts = 5120 watt hours
400 amp hours at 25.6 volts = 10240 watt hours
400 amp hours at 51.2 volts = 20480 watt hours

Put another way using the big blue prismatic cells that are popular here.
You need multiples of 4 cells to make a 12.8 volt battery.
You need multiples of 8 cells to make a 25.6 volt battery.
You need multiples of 16 cells to make a 51.2 volt battery.

280 amp hours * 3.2 volts * 4 cells = 3584 watt hours
280 amp hours * 3.2 volts * 8 cells = 7168 watt hours
280 amp hours * 3.2 volts * 16 cells = 14336 watt hours

Have you ruled out 24 volts?
Have you done an energy audit?

Look forward to answering your follow up questions.
Welcome to the forum.
 

Short_Shot

Photon Sorcerer
The biggest advantage of going with a 48v system is the wiring.
Debatable in a mobile application where your inverter should only be a few feet away tops, and you still need a ton of 12v stuff.

The other comments are very valid, however regarding panel voltage with lithium I find my mppt doesn't like to turn on nearly as early in the day because it struggles to get the panels over 18v needed to have the bat +5v on my victron.

I don't know if other mppts are subject to this or which ones if so though.

That said, if he's got a box truck he can and arguably should buy a few big residential panels with higher voltage anyways.

He's got the real estate with theoretically 16 feet of roof to put on as much as 4x santan solar 435w panels as long as the box is 7 feet wide or more. And that will still leave just enough roof space for a roof vent fan.

That's enough power to comfortably run an inverter style AC for fairly long hours and my suggestion there is the midea portable inverter that combines the in and out into one single hose. This avoids the need for any external mount at a small efficiency penalty.
 

Rednecktek

Solar Enthusiast
The fat wire involved is between your batteries and your inverter so since this is a van and there's not a lot of space I'm going to assume that your batteries are going to be pretty darn close. A foot of Fat/0 wire is really negligible, 25ft is Stupid$$$
Exactly. :) The wiring benefits don't really come into play here.
 

CubeTruck

New Member
400 amp hours at 12.8 volts = 5120 watt hours
400 amp hours at 25.6 volts = 10240 watt hours
400 amp hours at 51.2 volts = 20480 watt hours

Put another way using the big blue prismatic cells that are popular here.
You need multiples of 4 cells to make a 12.8 volt battery.
You need multiples of 8 cells to make a 25.6 volt battery.
You need multiples of 16 cells to make a 51.2 volt battery.

280 amp hours * 3.2 volts * 4 cells = 3584 watt hours
280 amp hours * 3.2 volts * 8 cells = 7168 watt hours
280 amp hours * 3.2 volts * 16 cells = 14336 watt hours

Have you ruled out 24 volts?
Have you done an energy audit?

Look forward to answering your follow up questions.
Welcome to the forum.
I read some of your stuff before signing up. Havent done an energy audit. Im also completely open to going 24v but your math is part of the reason I want to go 48v. Seems like im gonna get a lot more out of the system. You mentioned in one post that theres a link to the energy audit page in your signature. Idk if its my phone but I cant see a signature on your posts.

I found some 420 watt panels that already put out approx 48v for 4 panels I can get a 1680w system going for $1200 vs the 8 195w panels I was looking at for a 12v system 1560 watts, was gonna run me $1750. Ive got my rooftop real estate mapped out and I wanna do this right from the start.
 

CubeTruck

New Member
Debatable in a mobile application where your inverter should only be a few feet away tops, and you still need a ton of 12v stuff.

The other comments are very valid, however regarding panel voltage with lithium I find my mppt doesn't like to turn on nearly as early in the day because it struggles to get the panels over 18v needed to have the bat +5v on my victron.

I don't know if other mppts are subject to this or which ones if so though.

That said, if he's got a box truck he can and arguably should buy a few big residential panels with higher voltage anyways.

He's got the real estate with theoretically 16 feet of roof to put on as much as 4x santan solar 435w panels as long as the box is 7 feet wide or more. And that will still leave just enough roof space for a roof vent fan.

That's enough power to comfortably run an inverter style AC for fairly long hours and my suggestion there is the midea portable inverter that combines the in and out into one single hose. This avoids the need for any external mount at a small efficiency penalty.
Youre speaking my language brother :)

I cant order from Santan unless they have a Canadian Branch I dont know about, but I found someone selling some 420watt panels for 310 a piece. says he bought them to do a residential house but the project fell through.
 

Short_Shot

Photon Sorcerer
Youre speaking my language brother :)

I cant order from Santan unless they have a Canadian Branch I dont know about, but I found someone selling some 420watt panels for 310 a piece. says he bought them to do a residential house but the project fell through.
There are similar wattage units in that size range. I've done a lot of digging around to put stupid amounts of solar onto a roof and there are solutions for eliminating everything from the roof aside from panels.

However I really like my maxxair fan so I'll make the sacrifice there, though there are wall fans you can use if, say, you had a 14 foot box.

You could even go really nuts and do extending stacked panels and put 8 of the things on there.

Imagine having 3kw of solar. Even if you almost never use it, on a rainy day would still have a couple hundred watts coming in which would easily cover lights and gadgets. The stuff you *need* daily.

Even 1500w gives you the opportunity to cook and heat water with electric.
 

rmaddy

Solar Addict
Im also completely open to going 24v but your math is part of the reason I want to go 48v. Seems like im gonna get a lot more out of the system.

I found some 420 watt panels that already put out approx 48v for 4 panels I can get a 1680w system going for $1200 vs the 8 195w panels I was looking at for a 12v system 1560 watts, was gonna run me $1750. Ive got my rooftop real estate mapped out and I wanna do this right from the start.
I think there are several misconceptions here. Going to 48V does not mean you get more out of the system. If you bought 16 3.2V 100Ah battery cells you would have 16 x 3.2V x 100Ah = 5,120Wh of power. Those cells could be arranged into a 12V 400Ah battery, a 24V 200Ah battery, or a 48V 100Ah battery. All three are still 5,120Wh of power.

The panel volts are largely irrelevant if you use an MPPT solar charge controller. Put panels in an appropriate combination of series and parallel such that the combined Voc of the panels is at least 5V higher than your system voltage and the MPPT will be able to charge your batteries. You can use the 420W panels with either a 12V, 24V, or 48V system. You can use the 195W panels with either a 12V, 24V, or 48V system.

Your decision to use a 12V, 24V or 48V system should be based on the largest current (amps) needed in the system and that is typically determined by the size of the inverter you need. Need 1kW-2kW? Go 12V. Need 3kW-4kW? Go 24V. Need over 4kW? Go 48V. Of course you can go 48V with a 1kW inverter if you wanted. The previous guidance is more of an indication of the minimum. You can't (really really shouldn't) use a 5kW inverter with 12V because the amps are so high.
 

Short_Shot

Photon Sorcerer
24v is an excellent middle ground here in my opinion.

Though I will argue that 12v is more or less OK up to 3kw (but its a stretch) and 24v will take you to 5kw comfortably.

5kw from 12 would require much larger cables than are commonly available to consumers and I doubt there is a 12v 5kw inverter anyways. You could do, say, 2x 2500w inverters no problem but you start talking about real large bus bars here and its not worth the hassle.
 
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CubeTruck

New Member
I think there are several misconceptions here. Going to 48V does not mean you get more out of the system. If you bought 16 3.2V 100Ah battery cells you would have 16 x 3.2V x 100Ah = 5,120Wh of power. Those cells could be arranged into a 12V 400Ah battery, a 24V 200Ah battery, or a 48V 100Ah battery. All three are still 5,120Wh of power.

The panel volts are largely irrelevant if you use an MPPT solar charge controller. Put panels in an appropriate combination of series and parallel such that the combined Voc of the panels is at least 5V higher than your system voltage and the MPPT will be able to charge your batteries. You can use the 420W panels with either a 12V, 24V, or 48V system. You can use the 195W panels with either a 12V, 24V, or 48V system.

Your decision to use a 12V, 24V or 48V system should be based on the largest current (amps) needed in the system and that is typically determined by the size of the inverter you need. Need 1kW-2kW? Go 12V. Need 3kW-4kW? Go 24V. Need over 4kW? Go 48V. Of course you can go 48V with a 1kW inverter if you wanted. The previous guidance is more of an indication of the minimum. You can't (really really shouldn't) use a 5kW inverter with 12V because the amps are so high.
This makes things a lot clearer thanks! I was looking at batteries from the standpoint of Ah ratings alone. Very good to know about the charge controllers too.
 

noenegdod

Solar Addict
Ontario, just south of Toronto
There is a business called the Montana shipping outlet that is a mail box service. I ship most everything there (when the border was open) and pick it up. With the border opening again in the next few weeks I can start doing that again. Is there something like that available to you over there?
 
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