Written by:  Mohit Kaura @thelostcosmicdust

Your van’s electrical system can get complicated- fast. So we intend this article to be the prerequisite to building out your system. This article will give you a basic understanding so you can go forth and start planning the vanlife electrical system of your dreams.

What we will cover:

Introduction to electricity
  • – Common measures of electricity
  • – Units of measurement
Understanding your battery requirements
  • – Battery capacity
Understanding your solar requirements
  • – Determining the size of your solar power system
  • – Solar set up and positioning

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Introduction To Electricity

Let us begin with a simple introduction to common measures of electricity and the units they are measured in.

Current – Ampere (A)

Voltage – Volts (V)

Power/Wattage – Watts (W)

Energy Stored in your battery – Watt-hour (Wh) or KiloWatt-Hour (kWh) {{1 kWh = 1000 Wh}}

Current coming straight from the battery – Direct Current (DC, 12 V)

Current coming from the inverter/power strip – Alternating Current (AC, 110 V)

Keeping all the physics behind electricity aside, you have to only worry about the watt (or wattage) rating of your appliance.

If you have a device, say a fan, rated for 50 Watts, it will pull 50 watts of power every second.

Let us assume the following are your regularly used devices. The average wattage rating (How many watts they consume every second) is mentioned next to them.

Say, you want to run all of them at the same time. This will result in a total usage of:

50+10+10+70+60+40+700 = 940Watts

If you have an inverter rated at 1000Watts, you can theoretically run all these appliances without overloading the inverter.

NOTE: But say you run the microwave and the small blender at high speed together, your total usage will be: 700+350 = 1050 Watts, which will trigger an overload and the inverter will shut down. So, in this case, it will be beneficial to have a bigger inverter, say 2000Watts.

Simple mathematics, yeah?

Understanding Your Battery Requirements

 Now, let’s get to how long can you run these devices without draining your battery?

This depends on your battery capacity (same concept for Lead-Acid or Lithium-Ion), usually measured in kilowatt-hour (kWh) or Ampere-hour (Ah).

To convert Ah into kWh, simply multiply the voltage of your battery, as 1 Watt = 1 Volt X 1 Ampere.

Majority of van-lifers use a 12V battery system (though 24V and 48V are also common).

In Practice

So, how many hours do you think you can run 200Watts continuously on a 1200Wh battery?

If you said, 6 hours, Congrats! you now get the concept. (200Watt*6hr = 1200Wh)

Once you have estimated the total watts you need, choosing a battery bank size becomes easy.

So if you know you want to consistently run 100Watts, and you want your battery to last a few days or let’s say a total of 20 hours (100W*20hrs = 2000Wh), getting at least 200Ah (or2400Wh) would be beneficial.

Easy enough?

Understanding Your Solar Requirements

So now, you have your electrical needs figured out. You have the size of your battery and inverter picked out, and now you want to add solar power to recharge your batteries and be a sustainable van-lifing badass.

Choosing the size of your solar array depends on how much and how fast you want to charge your batteries.

Common solar panel arrays that van-lifers use range from 100Watts to 600Watts, depending on their needs and rooftop space availability.

An important factor to consider is that solar panels generally 75%-80% energy of what is listed, for example, a 100Watt panel will give you 80 Watts on a very sunny day at best.

Know that all days won’t be sunny, so always have extra energy on board. Keeping the battery at least half full at all times can be a lifesaver in bad weather conditions.

Say, you picked out a 200Ah (or 2400Wh), 12V battery and you want to charge it from completely dead to full. Assuming a 100-Watt panel can generate about 80 Watts consistently in direct sun on a clear day,

to charge a 2400Wh battery in this case will take 30 hours (80Watts*30hr = 2400Wh), which is clearly too long to wait, especially since you’ll only get 6-8 hours of full sun every day.

Here are some options for you for a faster charge.

A 300Watt panel producing 240 Watts on a clear day will charge your battery from dead to full in 10 hours. (5 hours if it is already half-full and so on).

This is obviously theoretical and there are minor discrepancies here and there, but I hope this section helped you understand your solar needs.