Battle of the voltages

Different voltages are being used across different industries for many years.

But which voltage is truly better, why, and most importantly – will that stay the case looking forward?

Looking at the range of standards that we have come to expect, we find:

  • 5V – The standard USB voltage, widely accepted for small loads.
  • 12V – The Standard across the Automotive industry.
  • 24V – The standard in Trucking and similar larger automotive.
  • 36V – The standard (ish) in the Marine industry.
  • 48V – The emerging standard for off-grid solar, cabins, etc.
  • Solar panels themselves don’t come in one set voltage, but rather span the entire range, from the single digits to thousands of volts, depending on the size, technology, and wiring of the array. also worth noting is that each solar panel will have more than one “number” next to it – a “40V” solar panel could mean slightly more or less than 40, depending on the temperature, intensity of the sun, VoC, Vpp, and many similar designations.

From there we go to Alternating Currents (AC) that are being used in residential homes and businesses:

  • 110V – used in North America.
  • 220V-240V – Used in the rest of the world.
  • 208V – 380V – Three phase current of the previous standards respectively.
  • EV – Electrical vehicle charge stations bring yet another complicated cocktail of possible voltages, both DC and AC combined, depending on the geography, brands, versions, etc.

So across the board, we have everything from 5-1500 Volts, DC & AC, each with its own code, rules, or best practices, some on their own while others get mixed into one device, making it quite a mess.

So, which should you choose?

5V USB should only be used where you know you will have a specific use for it, it is a dated standard that is quickly being replaced by USB Type C (or Lightning, or PD). it is better to leave a 12V socket, and use a small adapter if need be.

12V will remain at the forefront for many years to come. you can safely bet that a 12V socket will still be useful in the future and that any car will still have either a 12V battery or an adapter with a 12V socket. It is worth noting, however, that standard 12V sockets (“cigarette lighters”) are only rated to 10A or 120W. If you expect a bigger draw on any given appliance, then the socket of choice is the “Andersen plug” which comes in a range of ratings. An AC unit is one such use case, but certainly not the only one.

When we double our voltage, we can double our Wattage on the same Amp rating and the same wire sizing, or we can keep up with the same wattage while halving our Amperage, halving our required wire size and as a rule of thumb, reducing our cost of the hardware to about a quarter.

It does on the other hand mean a more complicated power design, with a Step-Up/Step-Down DC-DC converter, known as a Buck-Boost device.

It is a worthy upgrade, but one that will only suit a limited use case. If your system is very small, it makes more sense to suck up the losses and stay solely in the 12V realm. If however, you expect to invest more heavily in your electrical system (over 2000W inverter, or over 2KWh of batteries), then you may be better suited for an even bigger setup.

And the next setup is 36V. in this category you will find more marine-based companies and products. one such example is the Simarine Pico, which is a very nice control panel, suited for monitoring both electrical, water tank level, tilt angle, etc. Note that because this is an “odd” voltage for some, it will require a manual setup in some of the products by Victron for example (although the devices will work perfectly once set up, through the menu).

If, however, you expect to go all out on your electrical system, plan on a 3000W+ inverter, more than 3KWh of batteries, more than 3 solar panels on the roof, and you have the space/weight capacity to carry it – a 48V system is undoubtedly the way forward. We already see an influx of very good all-in-one systems (Solar MPPT charge controller + inverter + grid-tie charger), we will definitely see more of those, they are already cheaper than the systems mentioned above, coupled with batteries getting cheaper, and if a very convenient server rack form factor – the outcome will only drive more campervans into the 48V systems, while also being cheaper and more efficient.

Another likely outcome of this transition is the use of 110/220V appliances. A few years ago, a van had to use a 12V fridge, as residential ones required a wasteful inverter – today the inverter is much more efficient, is being run 24/7 anyways, and can idle at a negligible draw. At the same time, going with a small residential or dorm fridge can cost one-tenth of a comparably sized 12V RV-focused one.

Two other outcomes have not yet fully matured – charging from an EV charge station, and better-suited solar panels. While it is possible to charge a camper van battery from an EV charge station already today, we are still far from our full potential. both in terms of Voltage/Current/Wattage, as well as the communication protocol between the devices involved (the handshake, safety features, payment protocols, etc.). On the solar panel front, normal residential panels are less optimized for comper use, both in their dimensions (a 72/144 cell panel is too wide and long to fit well) as well as the internal structure of the cell. There are some 60/108/120 cell, monocrystalline panels, with 9BB, 10BB, and similar technologies that make them better suited already, and I expect to see even more advancements in the future, which will mean better efficiency for the average user.