This blog post is going to be a step-by-step guide on how to perform a power audit so you can ACCURATELY size your camper solar system based on YOUR own power consumption to determine how many batteries you need for your camper van electrical system.
Also, we have interactive solar wiring diagrams that are
Table of Contents
How to Size Your Camper Van Electrical System
You NEED to know how much power you use on a daily basis to determine the size of solar system you’ll need to power your camper.
Sure, you can buy a random solar kit and go for it, but more often than not, that tends to lead to disappointment in the performance of the system.
Be warned: This is an involved process. You’ll need to gather the items that you will be using (or look up their power usage) and put some numbers into the following spreadsheet you’ll need to download. After you’ve followed the step-by-step guide in this blog post, you’ll have a highly educated estimate of how much power you anticipate using throughout the day. This will give you a great baseline to determining how big of a camper solar setup you’ll need.
Step-by-Step Power Audit
What Appliances Will you be Powering?
You will need to gather as many of the items you will be powering. If you don’t physically have the items yet, you will need to look up their power consumption rates (or use the ones I have pre-filled in for you).
Not all Appliances are the Same
There are AC appliances, DC appliances, and DC components disguised as AC components. Confusing, I know. Hang with me, I’ll break it down.
These are items that you plug into your normal household plug. These will be items like a Coffee Maker, Instant Pot, Blender, Induction Cooktop, and a Vitamix.
TAKE ACTION: Gather all of these items into one pile and put a sticky note with “Table 1.1” next to them.
*But wait…there is a catch…*
DC Appliances disguised as AC Appliances
There are imposters in your ‘AC Appliances’ pile. There are likely items that plug into a normal household plug, that are actually DC appliances. These items are like Computers, video game consoles (
How to Identify these imposters: These items will have a ‘Wall Wart’ or an inline power supply AC/DC power adapter.
TAKE ACTION: Segregate these items into their own pile and label with a “Table 1.2” sticky note.
These items will be wired directly to your DC Distribution block (Fuse Block). These will be items like 12v light strips, 12v puck lights, 12v fans, Maxxair Fans, Water Pump, and 12v TV
TAKE ACTION: All of these items get their own special pile. Label it with “Table 1.3”. “Table 1.3”.
Single Charge Items
These will be items like Phones, Camera Batteries, Drone Batteries, External Charger Packs, Etc.. Basically, anything you charge up, then unplug to use.
TAKE ACTION: Put these items in a pile and sticky-note it “Table 1.4”
Full Day / Per Day use Items
These are items you will let run ‘all day’. 12v refrigerator that cycles off and on, Weboost 4g booster, hot water heater are a few examples.
*Note, The list is pre-populated with a few items for you to use as benchmarks, but if these items have already been accounted for in a previous table, there is no need to add them here.
*Note, The refrigerator listed in the pre-populated list is the ARB 65qt and most top loading 12v refrigerators will have similar electrical demands.
*Note, the hot water heater is a delicate calculation. The figure pre-input into the spreadsheet is for a 4 gallon Bosch hot water heater unit. It uses about 65 Amp hours to heat up, then it holds that heat for 12 hours-ish. The “Quantity” on that would be for “How many times do you plan on heating up 4 gallons of water”. Use this as a benchmark, but not a rule*
TAKE ACTION: These items go into yet another pile. Label it “Table 1.5”.
Performing a Step by Step Solar Power Audit
Now you have your 5 separate piles labeled with Tables 1.1 – 1.5, we are going to go through them, pile by pile, item by item and input the ACTUAL numbers to get you as close as you can get to a PROPER educated guess that will tell you how much solar power you will need based on how much power you use every day.
For all of these items you will need either watts and volts *OR* amps, *AND* a rough approximation of how many minutes per day you anticipate using the device.
Now, you’ll need the spreadsheet your downloaded earlier. (It was toward the top of this blog post)
Table 1.1 | 110v Appliances
Look for a plate on the device that tells you how many watts the appliance uses.
- Change the name of the Item as Necessary
- Input the Watts into column 2.
- Input the number of minutes you anticipate using the item per day.
Your spreadsheet has been pre-populated for popular appliances and power outputs. If your needs vary, alter as necessary by altering the GREEN columns. If you anticipate NOT using an item, you can delete the values in all of the GREEN columns, or simply input ‘0’ into the ‘Minutes Used Per Day’ Column.
Table 1.2 | AC/DC Adapter Appliances
Look for a sticker on the wall wart or AC/DC Converter that tells you how many amps and volts the is on the Output side of the cord. It’ll look something like this:
Table 1.3 | DC Appliances
DC powered appliances typically hide their power usage for some reason. If you look for a label or sticker with no success, usually looking online is the best option. You’ll be looking for the wattage of the device to insert it into column 2. If you find the amps and volts of the device instead, no worries! Table 1.3 has a
Table 1.4 | Single Charge Items
For Table 1.4, you will:
- Change Column 1 to the Device Name.
- Change Column 2 to the Battery Size of the Device.
- Change Column 3 to the number of times you plan to charge the device per day.
Table 1.5 | Full Day / Per Day Usage
Table 1.5 is for items that get used CONSTANTLY. You’ll have to take a constant measurement of your items over the course of 24 hours. This is good for things that cycle off and on like a refrigerator. The pre-populated ‘Refrigerator’ option is based on a top loading ARB 50qt 12v Refrigerator.
TOTAL: How Much Solar Power Do I need?
Now that you have filled in ALL the blanks with the electrical items you anticipate using throughout your normal day, check out ‘Table 1.6’. This is how many Amp Hours you will PERSONALLY consume per day according to all of your inputs as well as a recommendation for battery bank size, solar array size and a few other goodies:
The numbers you see are just general recommendations. Want to spend more time in cloudy environments? Maybe you should consider sizing up a bit. Budget can’t handle your recommended components? Perhaps size down (but PLAN for expansion). These are all just general recommendations that I feel confident in recommending. Any more is better. Any less is on you.
Now that you know how much battery capacity you need in your camper van electrical system, now it’s time to decide if you want to play the short or long game and go with AGM batteries or Lithium Batteries. Check out our comparison here: https://www.explorist.life/choosing-a-solar-battery-bank-for-a-camper/
Everything that you are learning here is put to use in our FREE Interactive Solar Wiring Diagrams. If you haven’t yet, check them out as they are a complete solution for a camper van electrical system. Check them out here: https://www.explorist.life/solarwiringdiagrams/
Remember, this is just one part of a full camper van electrical educational series. To see all of the individual guides, click here: https://www.explorist.life/diy-campervan-solar
Finally, If you found this guide helpful, It’d truly mean the world to us if you’d share it with somebody who can use it, pin it to pinterest for later reference, or share it to a facebook group when somebody has a question about this subject. Click the bubble in the lower right corner to subscribe to be notified of future updates and as always, leave any questions you’ve got in the comments below.
Wednesday 22nd of March 2023
I did the power audit, and despite having only an 1800W induction cooktop listed in the AC appliances table, the minimum rec at the bottom is calling for a 3000W inverter. Am I missing something? I even erased the AC/DC adapter components and it's still suggesting a 3000W inverter. Is 1800 too close to the 2000W threshold?
Thanks for all the help!
Saturday 19th of November 2022
uhh .! white text on a yellow background .. please ..!
Sunday 28th of August 2022
Nate, I just found the answer to my first question a couple of questions down. Apologies for the redundancy. Another question: since major appliances on our boat, like a refrigerator and freezer, are 220 volt which run continuously off the inverter, should some allowance for inverter efficiency (inefficiency) be made? That is to say the inverter consumes some power itself in heat loss etc. Should I add in some factor for that to the mains power consumption number?
Sunday 28th of August 2022
Totally brilliant Power Audit Spreadsheet. I had made my own but yours is so much better I embarrassed myself! Quick question: our “camper” is in fact a Narrowboat on the UK canal system, where 220 volt is standard for mains voltage appliances. I’m assuming no changes are required to your spreadsheet since the voltage difference is already “baked in” to the watts number ie a 220 volt appliance drawing 2 amps or a 110 volt appliance drawing 4 amps both draw the same wattage?
Thursday 18th of August 2022
Hi Nate, I live in Africa where the appliances are rated for 220v and your spreadshit mentions 110v, does this affect your spreadshit ?
If yes, can you tell me how ? or what do i need to change ?