Epic Guide to DIY Van Build Electrical: How to Install a Campervan Solar Electrical System

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Epic Guide to DIY Van Build Electrical: How to Install a Campervan Solar Electrical System

van build electrical

This post may contain affiliate links. Learn more >>

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When we first started thinking about our vanlife electrical system and buying our components, we had a lot of questions. We researched online, read other van build blogs and forum posts, and watched Youtube videos. Some were very helpful, but many left us with a swirl of even more questions.

What gauge wiring do we need? How do we go about grounding everything to the van? What exactly do we need to ground? What kind of fuses should we get? Do we need a fuse here? Do we need a switch there? How do we crimp battery cable? Where do we even get all this stuff?

We were learning a lot about circuits and electrical systems, but we were also overwhelmed by all the new knowledge coming at us from all directions. Electrical is such a vital part of any van build, and we wanted to get it right.

We longed for a resource that told us: Buy this. Connect it like this. Here’s a diagram.

This post is an attempt to make such a resource.

We go over exactly what we bought, exactly how we connected everything, and we even have pictures and diagrams (yay)!

For those of you interested in further reading, we also include links to blog posts and other resources that helped us out along the way.

We want this post to be as accurate and helpful as possible, so if we get something wrong or you want us to clear something up, let us know in the comments!

Obligatory Disclaimer: This post describes what we did with our own system based on our own research, and we hope you’ll find it helpful. That said, we are NOT ELECTRICIANS. Working with electricity in any form can be dangerous and lead to electric shock (or even explosion if you really screw up). It’s always a good idea to read the manuals for all of your components and consult with a licensed electrician before performing any electrical work.

Mega List of Everything We Used in Our Electrical Install

all the electrical components for our van build

Main Components

Renogy 400 Watt 12 Volt Monocrystalline Solar Starter Kit with 40A Rover MPPT Charge Controller1Renogy 400-Watt MPPT Solar KitCheck Price
Vmaxtanks VMAX SLR155 AGM 12v 155ah Deep Cycle SLA Rechargeable Battery for Solar and Golf, Pv Solar Panels, Smart chargers, Wind Turbine and Inverters.2VMAX 155-Ah AGM BatteryCheck Price
Xantrex Technology Inc, 49PWR-CL, 806-1210 Inverter Prowatt Sw 10001Xantrex PROwatt SW 100-Watt InverterCheck Price
Xantrex Technology Inc, E231, 808-9001 Remote Panel for Prowatt Sw1Xantrex PROwatt SW Remote SwitchCheck Price
MICTUNING LED Illuminated Automotive Blade Fuse Holder Box 10-Circuit Fuse Block with Cover1MICTUNING 10-Circuit Blade Fuse BoxCheck Price
Blue Sea Systems Common 150A 10-Gang BusBar with Cover1Blue Sea Systems Common BusBarCheck Price

Lights, Dimmers, and Outlets

acegoo RV Boat Recessed Ceiling Light 4 Pack Super Slim LED Panel Light DC 12V 3W Full Aluminum Downlights, Warm White (Silver)2Acegoo RV LED Ceiling Light 4-PackCheck Price
12 Volt DC Dimmer for LED, Halogen, Incandescent - RV, Auto, Truck, Marine, and Strip Lighting - Short Shaft - Silver212 Volt DC LED Dimmer SwitchCheck Price
BANDC Waterproof Marine Motorcycle ATV Rv Lighter Socket Power Outlet Socket Receptacle 12v Plug5BANDC 12V Lighter Socket OutletCheck Price

Wiring and Connectors

Camco 47444 Black 5/16' Stud 24' Long 4-Gauge Marine Battery Cable and Lug Assembly Tinned~Camco Marine Battery Cable (2 & 4 AWG, various lengths)Check Price
RGBSIGHT 40FT 18 Gauge Single Color LED Strip Extension Cable 18AWG 2pin 2 Color Red Black Stand Wire Conductor for LED Ribbon Lamp Tape Lighting (40 Feet per Spool)218 AWG Red/Black Strand Wire (40ft)Check Price
Ancor Marine Grade Primary Wire and Battery Cable (Red, 100 Feet, 14 AWG)1Ancor Marine Grade 14 AWG Wire, Red (100ft)Check Price
Ancor Marine Grade Primary Wire and Battery Cable (Black, 100 Feet, 14 AWG)1Ancor Marine Grade 14 AWG Wire, Black (100ft)Check Price
Gardner Bender 10-104 100PK Ring Terminal, 100 Pack, Blue116-14 Ring Terminals (100-pack)Check Price
Ginsco 110pcs Female Blue 16-14 Gauge Nylon Fully-Insulated Quick Disconnects Wiring Spade Wire Crimp Terminal116-14 Female Quick Disconnects (110-pack)Check Price
XtremepowerUS 158pc Electrical Wire Connection Screw Twist Connector Cap w/Spring Insert Assortment Kit1Wire Twist Connectors Assortment KitCheck Price
Gardner Bender HST-1300 Underground Cable Kit for Waterproof, 14-8 AWG, UF Copper Wire-Includes: 8 inch. Heavy-Wall Heat Shrink & Screw Splice Connectors1Gardner Bender 14-8 AWG Cable Splice KitCheck Price

Fuses and Cutoff Switches

Renogy 30A ANL Fuse Set w/Fuse (ANL Fuse Holder + 30A ANL Fuse)2Renogy 30A ANL Fuse Holder with FuseCheck Price
Absolute ANL100-2, 2 Pack ANL Fuses 100 Amp Gold Plated1100-Amp ANL Fuses, 2-packCheck Price
Kingopt Opt-4318 AWG Maxi Fuse HolderCheck Price
5 Pcs 40 Amp Large Blade Style Maxi Fuse for Car RV Boat Auto140-Amp Maxi FusesCheck Price
100 pcs Assorted Auto Car Trunk Standard Blade Fuse 2,3,5,7.5,10,15,20,25,30 35 Amp Car Boat Truck SUV Automotive Replacement Fuses Auto Holder Fuse Kit Car Accessories1Assorted Blade Fuses, 100-packCheck Price
BEP 701 Battery Switches - On-Off2BEP Battery On/Off SwitchCheck Price

Essential Tools

IRWIN VISE-GRIP Wire Stripping Tool / Wire Cutter, 8-Inch (2078309)1Irwin Electrician's MultitoolCheck Price
Screwdriver and Nut Driver 11-in-1 Multi Tool, Industrial Strength Bits, Cushion Grip Handle Klein Tools 325001Klein Ratcheting ScrewdriverCheck Price
BLACK+DECKER 20V MAX Cordless Drill/Driver Variable Speed (BDCDD220C)1Black & Decker 20V Cordless DrillCheck Price
Renogy MC4 Tool Assembly and Disassembly Tool Solar Panel Cable Crimping Tool for Male/Female MC4 Connectors1Renogy MC4 Assembly ToolCheck Price
Duck Brand 299019 Professional Grade Electrical Tape, 3/4-Inch by 66 Feet, Single Roll, Black1Electrical TapeCheck Price

Update From the Road: Why You Need a Smart Battery Isolator

There’s one more component that we’ve discovered is vital to have on the road: a smart battery isolator.

12V 140 Amp Dual Battery Smart Isolator by KeyLine - VSR - Voltage Sensitive Relay Specially Designed for ATV, UTV, Boats, RV's, Campers 5th Wheels Off Road Vehicles Rhino Polaris Artic Cat ETCWe originally had the Keyline Chargers 140-Amp Smart Isolator and it worked flawlessly. We have since switched to the Wirthco Battery Doctor 125A/150A Battery Isolator because of its jump start feature.

A smart battery isolator allows you to charge your auxiliary batteries from your vehicle’s alternator while driving. This is a great supplement to solar panels, especially if you’re spending time in overcast or heavily forested environments where you don’t get as much sun.

Budget Note:

If you only have a few hundred dollars to spend on your electrical system, we recommend starting with a good battery, a smart isolator, and an inverter. You can always add solar later.

Check out this detailed post for more information on battery isolators, what kind to get, and how to install one.

What Does All This Stuff Do?

That’s a pretty intense list. But don’t worry, it’s really not all that complicated. Let’s break it down from a bird’s eye view.

how solar power works for van life

The Sun
It all starts with the sun. The sun not only gives us life, it also constantly beams energy to us here on Earth. Using science, we can convert this energy into electricity to power vanlife!

Solar Panels
Solar panels absorb light from the sun, convert it into electricity, and send it on to the charge controller.

Charge Controller
The charge controller regulates the flow of electricity from the solar panels and uses it to charge your batteries.

The batteries we use store electricity at 12-Volt DC (direct current), which can power your lights, exhaust fan, fridge, USB/cigarette lighter outlets, and anything else that runs on DC. In our system, the electricity is fed from the batteries back to the charge controller, which then distributes it outward.

If you want to power something like a computer or other complex electronics that require a 3-pronged wall outlet, you’ll also need an inverter, which converts 12-Volt DC to 110-Volt AC (alternating current). This is connected directly to the battery.

That’s basically what’s going on in a 12-Volt van solar power electrical system. Everything else just connects the dots.

How Much Electricity Do You Need?

It’s a good idea to think about how much electricity you’ll use when deciding how many solar panels you need and how big your batteries should be. This can get a bit complicated, especially since there’s a lot you just don’t know about your usage if you’ve never lived in a van before.

But, if you want to make sure you have enough electricity to meet your daily usage while also not paying for more than you need, then going through the exercise of sizing your system is the best thing to do.

How to Size Your System

First, calculate the number of watts of electricity you use, then multiply it by the number of hours you use that electricity to figure out how many watt-hours (Wh) of electricity you use.

Watts x Hours = Wh

So, if your lights use 5 watts and you have them on for 5 hours each day, their power consumption is 25 Wh per day.

For this example, let’s pretend all your electrical components use 1200 Wh each day.

Battery capacity is measured in amp-hours (ah), so to figure out how big your battery needs to be, convert the 1200 Wh of power consumption into ah by dividing by the system voltage (12V).

1200 Wh / 12V = 100ah.

If you ran that calculation and think you need a 100ah battery, well then…you’d be wrong.

See, you never want to fully deplete your battery.

If your battery drops below about 50% you risk shortening its lifespan and/or damaging it, so in this example you would need at least a 200ah battery to accommodate 100ah of power consumption per day.

You then need to figure out how many solar panels you need to fully charge your batteries each day.

Solar panels are in watts, so we’ll again use our 1200 watts of power consumption. Let’s divide that by the average amount of full sunlight per day (say, 5 hours) to get our solar panel size.

1200 Wh / 5 hours = 240 watts. So, a 240-watt solar panel should, in theory, fully charge your battery each day and accommodate your power consumption.

Except that it never works that way. There’s shade, and clouds, and less sun in winter, and days where you consume more power than others. Something like three 100-watt panels would be a much safer bet.

Rules of Thumb on System Sizing

To make sure you’re not draining your batteries too much, your battery capacity should be at least two times your power consumption. So, if you consume 100ah per day, you should have a minimum 200ah of battery capacity. More is better.

According to this awesome page, here are some guidelines on what kind of usage you can expect:

  • 6ah = ultra conservative usage
  • 35ah = modest usage
  • 120ah = living like you do on the grid

A good rule-of-thumb is to match your solar panel wattage to your battery Ah capacity. So, you would want at least 200 watts of solar panels for 200Ah of battery capacity.

Budget-Based System Sizing

Sizing your system appropriately can be challenging, especially if you’ve never lived in a van before. There’s just a lot you won’t know about your real-world usage, and a lot you won’t be able to foresee before you hit the road.

Another method is taking a budget-based approach to your electrical system, and adding capacity as-needed.

If you have a barebones budget, you don’t need a huge, expensive solar setup. But if you can afford it, having a large system will make your life easier and means fewer compromises in your electrical usage.

Here are the main components we recommend for different budget levels:

Barebones Budget

WirthCo 20092 Battery Doctor 125 Amp/150 Amp Battery Isolator1Battery Doctor Smart Battery IsolatorCheck Price
Vmaxtanks Vmaxslr125 AGM Deep Cycle 12v 125ah SLA rechargeable Battery for Use with Pv Solar Panels,Smart chargers wind Turbine and Inverters1VMAX 125Ah Solar AGM BatteryCheck Price
Xantrex Technology Inc, 012-TR1000 8 X 3/4, 806-1206 Inverter Prowatt Sw 6001Xantrex PROwatt SW 600-watt InverterCheck Price

If you have a tight budget, starting off with a good inverter, a battery, and a battery isolator should meet very basic electrical needs (charging phones/computers, some lights). You can always add on solar capabilities later if you need to.

Midrange Budget

Renogy 200 Watt 12 Volt Monocrystalline Solar Starter 20A Rover MPPT Charge Controller/Mounting Z Brackets/Tray Cable/Adaptor Kit1Renogy 200-watt Solar KitCheck Price
Vmaxtanks Vmaxslr125 AGM Deep Cycle 12v 125ah SLA rechargeable Battery for Use with Pv Solar Panels,Smart chargers wind Turbine and Inverters2VMAX 125Ah Solar AGM BatteriesCheck Price
Xantrex Technology Inc, 49PWR-CL, 806-1210 Inverter Prowatt Sw 10001Xantrex PROwatt SW 1000-watt InverterCheck Price
12V 140 Amp Dual Battery Smart Isolator by KeyLine - VSR - Voltage Sensitive Relay Specially Designed for ATV, UTV, Boats, RV's, Campers 5th Wheels Off Road Vehicles Rhino Polaris Artic Cat ETC1Keyline Chargers Smart Battery IsolatorCheck Price

This midrange setup gets your started on the right foot, with more battery capacity and 200-watts of solar. This setup is completely expandable, so you can add more panels later if you need to.

Higher Budget

Renogy 400 Watt 12 Volt Monocrystalline Solar Starter Kit with 40A Rover MPPT Charge Controller1Renogy 400-watt Solar KitCheck Price
Vmaxtanks VMAX SLR155 AGM 12v 155ah Deep Cycle SLA Rechargeable Battery for Solar and Golf, Pv Solar Panels, Smart chargers, Wind Turbine and Inverters.2VMAX 155Ah Solar AGM BatteriesCheck Price
Xantrex Technology Inc, 49PWR-CL, 806-1210 Inverter Prowatt Sw 10001Xantrex PROwatt SW 1000-watt InverterCheck Price
12V 140 Amp Dual Battery Smart Isolator by KeyLine - VSR - Voltage Sensitive Relay Specially Designed for ATV, UTV, Boats, RV's, Campers 5th Wheels Off Road Vehicles Rhino Polaris Artic Cat ETC1Keyline Chargers Smart Battery IsolatorCheck Price

If your budget allows, a system this size should cover most electrical needs (unless you’re trying to run an AC or electric heater). Over 300Ah of battery capacity, a smart isolator, and 400-watts of solar mean you’ll never have to worry about plugging in!

Choosing Solar Panels and Batteries

What We Went With: 400-Watt Renogy Starter Kit with MPPT Charge Controller and Two VMAX 155ah AGM Batteries

Renogy 400 Watt 12 Volt Monocrystalline Solar Starter Kit with 40A Rover MPPT Charge ControllerSince we didn’t know enough about what our electricity needs would be, we had a tough time calculating the exact size that our system needed to be. From watching Youtube videos and reading blogs, it seemed like many vandwellers just barely scrape by with two 100-watt solar panels, so we decided to go with the biggest system we could afford.

We bought Renogy’s 400-watt starter kit with the 40A MPPT charge controller, and paired it with two VMAX 155ah batteries (for 310ah of total capacity). We were only able to fit three of the panels on our van’s roof, but we’ve got the fourth stashed under the bed.

We built a foldout PVC frame for this “extra” panel so we can prop it up and plug it in when needed. This lets us park in the shade on really hot days while still charging our batteries from the sun.

Is our system too big? We don’t think so.

Having this much solar allows us to be 100% off-grid, and we rarely have to worry too much about our power consumption. We’ve met people on the road with smaller systems that regularly worry about making sure they have enough juice to keep their fridge running.

And even with a system this big, we have run low on juice in certain scenarios. If we’re in overcast climates or heavily forested areas (or both) for more than five days or so, and if we’re staying in one place and not driving much, then our batteries start to get down to the 12.0V-12.2V range in the morning. But because of our system size, we can boondock longer in the same spot, in all weather and environments, and still do everything we need to do.

Can you get by with less? Absolutely.

If you’re tight on funds, Renogy’s 200-watt kit paired with a smart battery isolator is a great place to start. You can always add more panels later.

Whatever you go with, we recommend getting an MPPT charge controller instead of a PWM controller. MPPT controllers are able to squeeze higher efficiency from your solar panels. They’re supposedly up to 25-30% more efficient than PWM controllers. MPPT controllers are more expensive up front, but they’ll allow you to stretch your system much further.

(Very, Very, Very) Basic Circuitry: What You Need to Know

Going too deep into basic electronics is beyond the scope of this post, but it definitely helps to visualize how a simple circuit looks when designing your system.

Here’s a diagram of a very basic DC circuit:

DC circuit-diagram

Closing the switch completes the circuit and allows electricity to flow between the battery and the lights. One common analogy used here is that of a water pipe. If there’s a break in the pipe, water won’t be able to flow.

A fuse is an intentional weak point in a circuit. It’s there for safety. If too much current flows through the circuit, the fuse will “blow” and break the circuit.

“Grounding” in van life electrical is a connection to the vehicle’s chassis. In our install, we grounded the battery and the inverter.

For further reading about how electrical systems work in the context of a van, we highly recommend checking out Van Dog Traveler’s ebook. It’s packed with detailed information on electrical (and other aspects of a van build).

Designing Our System (With an Awesome Wiring Diagram!)

In designing our system, we leaned heavily on wiring diagrams we found on the internet, particularly the one in this post by Van Dog Traveller (his ebook has even more detailed diagrams. Seriously, get it).

But all the diagrams we found gave us a lot of partial information or only halfway applied to our system, and led to some confusion on our part.

After all of our research, we couldn’t find an all-encompassing diagram that showed us exactly how everything in our system fit together. So we made one.


We highly recommend diagramming your system so you know exactly how everything is supposed to connect. Just drawing it out really helps you think it through and get it straight in your head.

Making Sure You Have the Right Size Wires and Fuses

This can be a bit confusing if you’re new to electrical work. But it’s important to get it right if you don’t want to deal with any electrical or safety issues down the road.

Below, we break down exactly how to calculate the wire sizes you need, and give you some tips on selecting the right fuses for your circuits.

Choosing the Correct Wire Sizes

Ancor Marine Grade Primary Wire and Battery Cable (Red, 100 Feet, 14 AWG)Choosing proper wire sizes is an important step in any electrical install. If your wires are too thin, it can be a significant safety hazard. If your wires are too thick, you’ll be spending more than you need and your wiring will be harder to work with.

Note: In the United States, wire size is measured in American Wire Gauge (or AWG). AWG gauges may be different than wire gauges used in other countries. Since we are in the US, we used wires measures in AWG for our electrical install.

The size wire that you choose should be based on the amount of current going through the wire and the length of the wire run. You want to use a wire size that’s thick enough to safely handle the electrical current without experiencing too much voltage drop.

How do you figure out the max current that will be going through your wires?

Your lights, appliances, and other electronics should have their max current available in their technical specifications.

For DC appliances this should be listed in amps (max amperage). If for some reason your component specs lists this in watts, divide that number by the system voltage (so divide by 12 for a 12V DC system).

How do you figure out the length of your wire run?

First, you’ll need to measure the distance the wiring is going to travel. Then double it.

What?! Double it?! Yup. When calculating wire sizing for DC systems, the wire length refers to the total length of both the positive and negative wire.

So, if you’re wiring an outlet that will be 5 feet from your fuse box, your wire length is actually 10 feet – 5 for the positive wire, and another 5 for the negative wire to complete the circuit.

Okay, so now that I know my max current and wire length, how do I figure out what wire size I need?

Blue Sea Systems has an awesome “Circuit Wizard” calculator on their website that can help you determine the proper wire size for what you need.

Simply enter the system voltage, the max current, and the total wire length. The calculator will spit out the recommended wire gauge for you:

blue sea systems circuit wizard
Blue Sea Systems Circuit Wizard wire sizing calculator

We also found this helpful automotive wire sizing calculator from Wire Barn that shows you more detail on what gauges will or won’t work, as well as other pieces of information like voltage drop for each.

Here’s an example using our Acegoo 12V LED lights:

acegoo RV Boat Recessed Ceiling Light 4 Pack Super Slim LED Panel Light DC 12V 3W Full Aluminum Downlights, Warm White (Silver)

We have a 12V electrical system, so we’ll use that as our system voltage.

System voltage = 12V

Per the tech specs on our Acegoo 12V recessed LED lights, they have a max current of 3W per light. To convert that to amperage, we divide by the system volume (3W / 12V = 0.25A).

Each light is wired individually to the switch, so we need wire that can handle 0.25A of current.

Max current = 0.25A

We planned on installing each light no more than 6-10 feet from the switch (we’ll assume 10 feet to be on the safe side). To get our total wire length, we’ll multiple 10 feet by 2 to account for both the positive and negative wire.

Wire length = 20 feet

Plugging all these numbers into the Circuit Wizard spits out a recommend wire thickness of 22 AWG. (We ended up using 18 AWG to be extra safe).

But that’s not all. We also need to wire the dimmer switch down to the fuse box. Since we have sic LED lights wired to one dimmer, we need to multiply the light current by 6 to get our max current:

Max current = 1.5A

The distance between the dimmer and fuze box is about 4 feet. Double that to get the total wire length:

Wire length = 8 feet

Plugging these numbers into the Circuit Wizard gives us a recommended wire gauge of 18 AWG. (We ended up using 14 AWG here, again to be safe, and so we could use the same wiring for our dimmer switches and outlets).

You’ll want to run this same calculation to get the proper wire sizes for all your components. In general, the wiring for things like lights, outlets, fan, fridge, and other DC components will be probably between 12 AWG and 18 AWG.

You’ll need much thicker wiring for your batteries, inverter, and ground cables. Again, you’ll want to calculate this yourself based on max current, length, and manufacturer recommendations. We used mostly 4 AWG battery cable for the batteries, and thicker 2 AWG cable for the inverter and ground connections.

Choosing the Correct Fuse Sizes

100 pcs Assorted Auto Car Trunk Standard Blade Fuse 2,3,5,7.5,10,15,20,25,30 35 Amp Car Boat Truck SUV Automotive Replacement Fuses Auto Holder Fuse Kit Car Accessories

Choosing the right fuse sizes for your circuits is very important for safety. A fuse is an intentional weak point in a circuit. If the current in the circuit ever gets dangerously high, the fuse will “blow,” breaking the circuit and saving you from some major electrical problems.

For your electrical loads (lights, outlets, fan, fridge, etc.), we recommend wiring everything into an automotive blade fuse box and picking up a set of blade fuses.

As a general rule, choose fuses that are above the max current of your circuit load, but below the amperage rating of your wiring.

Going back to our LED light example – the total max current of our light circuit is 1.5A. So, we fused this circuit with a 2A fuse. This is above the max current of our lights, but well below the amperage rating of the 14 AWG wiring we used.

For larger items like your batteries and inverter, you’ll want to use a different type of fuse. We used ANL fuse holders with the proper fuses for our batteries and inverter, and an inline Maxi fuse holder to fuse our solar panels.

Make sure to check the manuals for your solar charge controller, inverter, and batteries for manufacturer-recommended fuse sizes.

Cutting and Crimping Wires

IRWIN VISE-GRIP Wire Stripping Tool / Wire Cutter, 8-Inch (2078309)

How do all these wires connect to each other? With crimp connectors!

We used two kinds of crimp connectors in our van build: ring terminals and 1/4″ female quick disconnects.

Pick up a basic electrician’s multi-tool and you’ll be crimping wires in no time. Check out this Instructables article for a tutorial on crimping wires.

Crimping terminals onto thicker battery cable is a little more difficult, so we mostly bought short lengths of cable with the ring terminals already attached. However, you could save some money if you can buy cable in bulk and crimp it yourself.

Connecting the Dots: Step-by-Step Installation of Our Electrical System

Here’s the part where we go through how we installed all the pieces of our electrical system. Between cutting and crimping wires, arranging and organizing components, making mistakes and figuring things out as we went, this whole process took us a few days.

Mount and Wire the Solar Panels

installing solar panels

Important: DO NOT hook up your solar panels to the charge controller until the batteries are connected.

The first thing we did was mount our solar panels to our van’s roof and wire them together in parallel using a Signstek Y-branch wiring connector.

For parallel wiring, all the positive wires go together and all the negative wires go together.

We decided to wire our panels in parallel for a few reasons:

  • Parallel allows us to hook up the three panels on our roof and connect our fourth panel whenever we want.
  • With panels wired in series, if some shade gets on one of the panels the electrical output of the entire system will be affected. With panels wired in parallel, shade will only affect that one panel.

There are advantages and disadvantages to both parallel and series. Renogy has an awesome guide on the differences.

After we mounted our panels, we fed the wires inside the van and ran them through some conduit down to where we planned to put all of our electrical components.

Mount the Charge Controller

mounted charge controller_800x500

Next, we mounted our charge controller to the wall inside our van. Renogy recommends leaving a few inches of space all around for ventilation.

Wire Batteries Together in Parallel

wiring batteries together in parallel

If you have more than one 12V battery, wiring them in parallel is the way to go for a van system. To do this, connect the positive terminals together, then connect the negative terminals. We used 4 gauge battery cable for this.

Next, we grounded our batteries to the vehicle chassis. We used 2 gauge wire for the ground connection. We screwed the ring terminal directly to the vehicle frame using 1-⅝” self-tapping screws and shake proof lock washers. The connection is rock solid.

grounding wires

How to Properly Wire Your Batteries

When you connect everything to your batteries, make sure you do it on opposite sides of your battery bank. What does that mean exactly?

Attach all of your positive wires to the positive post of one battery, and connect all of your negative wires to the negative post of the other battery. This allows your batteries to charge and discharge at the same rate and will help keep them healthy.

wires on opposite battery terminals

Check out this page for helpful diagrams showing how to wire together different sized battery banks in both parallel and series.

Wire Charge Controller to Batteries

For this step, we used the leftover 8 AWG wire that came with Renogy’s kit, crimping on ring terminals as needed. First, we ran 8 AWG wire from the positive battery terminal on the charge controller to one side of a heavy duty on/off switch. This will let us kill the connection to the battery if we ever need to.

Note: DO NOT disconnect the battery while the solar panels are hooked up to the charge controller. Whenever we need to cut off power to work on the system, we always make sure to disconnect our solar panels first.

close up of battery switch mounted

Next, we ran 4 AWG wire from the other side of the switch and connected it to one side of an inline fuse holder (we switched to 4 AWG here, but you could keep using 8 AWG wire here without any problems). The fuse should match the current rating of the charge controller (i.e. a 20A fuse for a 20A charge controller. We used a 30A fuse). Then, we ran 4 AWG wire from the other side of the fuse holder to the positive post on our battery.

anl fuse holder

Now that we had the positive connected, we ran a wire from the negative battery post and connected it to the negative battery terminal on the charge controller.

screwing batteries into charge controller

As soon as we made the connection, the charge controller turned on. Exciting!

Make Sure to Fuse Your Solar Panels

Renogy recommends adding a fuse in between your solar panels and your charge controller. Here’s what we used:

Wire Solar Panels to Charge Controller

connecting solar panels to charge controller

This was simple enough. We inserted the positive wire from the solar panels into the positive solar terminal on the charge controller, then did the same with the negative wire. Now the solar panels were charging the batteries!

Wire the Load Terminals to the Charge Controller

charge controller wires

We ran 8 AWG wire from the positive load terminal on the charge controller to the terminal on our blade fuse box.

To get your 8 AWG wire, you can use leftover wiring from the solar panels and crimp a ring terminal onto one end.

close up of grounding bus and fuse box

Next, we ran another 8 AWG wire from the negative load terminal on the charge controller and connected it to the terminal on our Blue Sea Systems common bus bar.

Note: You don’t need a separate bus bar for the negative connections if your blade fuse box has both positive and negative terminals, like this one from Blue Sea Systems.

Important Note

Twist connectors are NOT designed for automotive use, and if not installed properly there is a chance that they can vibrate loose. To help prevent this, after forming your twist connection wrap the wires together with electrical tape just below the twist connector. This helps take pressure off the connection point and make it less vulnerable to coming loose.

Installing the outlets was much simpler.

We first drilled holes and mounted them in place.

outlets in bench

Then we crimped quick disconnects onto both red and black wires and connected them to the back of the outlets.

fridge outlet from behind

We attached the other side of the positive wire to the blade fuse box using a quick disconnect, while the negative wire attached to the negative bus with a ring terminal.

The fan was the simplest.

Using butt connectors, we crimped additional wire onto the positive/negative wires coming to the fan. We then attached the positive wire to the fuse box using a quick disconnect, and attached the negative wire to the common bus bar using a ring terminal.

Wire Lights, Dimmer Switches, and Fan

Next, we connected our LED ceiling lights, vent fan, and outlets to the system. We used 18 AWG wire for the LED lights and 14 AWG wire for the outlets and fan.

Before we hung the ceiling we had attached wires to the lights and fan using twist connectors, and wrapped  it with electrical tape to prevent the connection from vibrating loose.

light hanging by wire

Then we labeled the wires and ran them through conduit down to the electrical area. So all we had to do now was connect everything together.

We hooked up the lights to dimmer switches.

We rigged up one dimmer switch in the front controlling a set of six lights, and another dimmer in the “bedroom” controlling two lights.

The awesome dimmer switch we used comes with three wires: a positive, a negative, and a ground.

front lights switch

Using a twist connector, we twisted together the positive light wires, the positive wire from the switch, and another wire that ran down to the blade fuse box.

We then twisted together the negative light wires and the negative switch wire.

We spliced the “ground” wire from the switch to a separate wire that connects to the negative bus bar.

Insert Blade Fuses into Fusebox

fuse box - horizontal

Without fuses, the circuit isn’t complete. When designing your system, you’ll want to base your fuse sizes on the max amperage of the circuit.

Hit the Switch Aaaaannnndd……

This is when things should turn on. But for us, nothing happened. We tried turning on the fan, turning on the lights – nothing.

It turned out that we had our charge controller set to cut off power to the load. If you get to this point and nothing turns on, check your charge controller settings!

Once we got the settings correct everything worked beautifully. The lights dimmed on and off, the fan turned on, the outlets charged our phones.

lights and fan on

Wiring the Inverter to the Battery

We mounted our inverter to the outside of the partition that separates the electrical enclosure from the storage area under the bench.

view from countertop with inverter
The inverter connects directly to the battery.

First, we ran wire from the positive battery post to a heavy duty on/off switch so that we can cut the power to the inverter if needed.

inverter switch and fuses

Next, we ran wire from the switch to an inline fuse holder with 100A fuse. We used one of Renogy’s ANL fuse holders and replaced the 30A fuse it came with. From there, we connected a wire from the fuse holder to the positive terminal on the back of the inverter.

behind inverter

The negative wire goes directly from the negative battery post to the negative terminal on the back of the inverter.

Finally, we grounded the inverter to the van’s chassis using self-tapping screws and shake proof lock washers.

The inverter has regular 3-pronged outlets on the front. You can plug your AC devices directly into these outlets, or run an extension cord to a power strip or AC outlet elsewhere.

We have two 3-outlet extension cords plugged into our inverter, and we mounted the outlets in a convenient location.

Tip: Keep Things Organized!

Trust us, your life will be so much easier (and safer) if there isn’t a jumble of live wires spewed all over the floor of your van.

We concealed all of our electrical components in a compartment under the seat of our flip top bench. We screwed our blade fuse box to the floor and screwed our switches, inline fuse holders, and inverter to the plywood walls of the enclosure.

van life electrical neat and tidy

We used ½” metal wire straps from Home Depot to organize the thick battery cables, and smaller wire clips to hold down the smaller wires.

This keeps the wires out of the way, and also takes tension away from the electrical connections so they’re less likely to come loose while driving.

Awesome Resources for Further Reading


That’s just about everything we did for our electrical install. We tried to answer all the questions we had when we started out, and some questions that we had right up to the installation. If there’s something we didn’t cover, or you have a question, or we got something wrong, let us know in the comments!

We’re supremely pumped to have power in our van – it definitely makes those late night van build sessions a lot easier!

Stay tuned for more build updates as we go into building our awesome furniture. And don’t forget to follow us on Instagram @gnomad_home and on Facebook at Gnomad Home.


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JohnDeb BryantSyd LeeVarun SharmaAndrew L Wehba Recent comment authors
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should I connect my 12v fuse box to my batteries? Does connecting the fuse box to the charge controller allow the go from the solar panels directly to the fusebox? What happens when there is no sun do you lose power to the fuse box?


In your diagram there is nothing coming out of the inverter. I thought the purpose of the inverter is so that you can have normal mains power plug socket. If this is the case, where is this shown on the diagram ?


One other question. In your post here: https://gnomadhome.com/build-your-van/#electrical you say that every DIY solar project has a battery monitor. I can’t find where you mention this in this post or in the diagram ?

Thanks for the detailed info 🙂


You mention talking to Renogy tech support in your “Designing Our Awesome System…” section before the wiring diagram but you never explained the resolution. From your wording and diagram it seems you may have a “positive ground” charge controller, hence the need for all your auxiliary wiring to be a complete loop back to the controller (as opposed to a negative ground which allows you to power accessories from the positive terminal and then ground to the chassis…as is typical in automotive applications). While it would require more wiring, I actually like the idea of grounding all accessory loads back… Read more »

Bob Phillips
Bob Phillips

I’ve got to second Zach’s grounding preference. Boats, for instance have battery grounding separate from onboard metals which may be part of a different bonding connection, for reasons related to electrolysis. For an RV, the chassis does nothing by way of providing a true ground, although it does offer a fast and dirty common for negative wiring, if all circuits and batteries are so connected. It also makes possible voltage differentials between the starter battery circuits and the house battery circuits. While those differences are likely to be small, the associated current flows could have unexpected consequences. If running a… Read more »


Did you ground both your batteries with 1 or 2 cables? In the grounding picture you showed two wires, but I could only see 1 with the shake proof washer. Much appreciated.


Fantastic blog post guys! Quick question, did you guys run wiring for lights, speakers, etc. in the walls before putting the walls up? We’ve just finished insulating and are debating holding off on putting our walls up to run the wiring vs. doing the wiring post facto. How did you guys do it?


This is a fantastic post thanks for the detail and diagrams. One question: Do you run your inverter into 120VAC wall sockets in your van or just use an extension cable. Any safety concerns with either of these?

Another question: This system seems much bigger than I typically see in van conversions. Knowing what you know now, would you have sized the system (solar capacity, battery bank) any differently?

Thanks again

Tom Dohr
Tom Dohr

You installed an inverter, but I did not see any 110v outlets in your instructions. Isn’t that what an inverter is for, to change dc to ac? What did I miss?

Paul Kaczmarek
Paul Kaczmarek

Thanks for the post. Amazing write up and descriptions. Exactly what I was looking for to start wrapping my head around this? Question for ya, as I am having trouble finding any info out there. You’ve wired directly to the controller, your lights, fan and outlets, I assume the lights and fan you purchased run directly on 12V DC current I thought regular lights needs AC, and I assume the outlets are for 12VDC appliances, like a refrigerator or appliances specific to RV’s? And I also assume the inverter would be for your laptop and iphone charging? Just trying to… Read more »


Dude, this is beautiful work, the simplicity of your explanation makes all the difference, your electrical diagrams are awesome, I really enjoyed reading the whole article, thanks so much for sharing.


I am thinking about installing the Renogy 200 watt solar kit on my teardrop trailer, it is a Runnerway camper. Do I ground the battery underneath the camper’s metal frame like a vehicle’s frame mentioned in your article?


Hi John,

I’m about to pull the trigger on solar for my own van build. I really appreciate the detailed product list and write-up. It’s exactly what I am looking for given my lack of knowledge on the topic. Would you do anything different in retrospect?



I love this post! I’m a complete newbie when it comes to electric, and that’s been stressing me a bit about my upcoming build. I’m just going to do everything you’ve done here – easy peasy!

I was making my Amazon list from your links, and I think some of them have got mixed up! The first link is a Renolgy 400 watt kit, but it links to a 50 watt. And next are the two 155ah batteries, but the link goes to a Y branch adaptor. Am I mixed up?


Hi John.

Finally I found a site after months of searching that makes since and in detail with photos and clear instructions.
Very awesome!
Thanks for taking time out of your schedule to post this.
I am converting a cargo v-nose trailer into a camper and will keep you posted on my progress.
Cheers, Wally


A question I did have is why you decided on the 12 volt batteries and not 2 6volt batteries?


First of all, thank you so much for taking the time to put this website together, I cannot imagine the amount of time that this must have taken and this is so helpful to many of us!!! I have a question regarding the wiring of the lights. The ceiling lights have 22 AWG wires and the wires that are running from my switch to my lights is 14 AWG. I am wondering how to connect the two together. All the heat-and-shrink connectors I looked at are not meant for two wires with such different gauges. What size wire did you… Read more »


Hi John.
Not sure if you saw my question on how well your 2 12 volt batteries are doing and any issues?
Also sent you a little donation for your time.


Your guide is awesome! Just one question though. If I install all four panels, do I use a 40A fuse from the solar panels to the contoller, as well as on the positive from the battery to the controller?

Shane Eudy
Shane Eudy

Hey John, this is a great diagram. I’m a little lost on what size of wire you used going from the control panel to the batteries and the fuse block. I know you said 4 gauge but looking at the controller, it can only take up to an 8 gauge.

Deeanna Bennett
Deeanna Bennett

This is the BEST explanation of a DIY electrical system I’ve seen so far! Thanks for the great advice! I was wondering… roughly, how much did you spend on your system all together? Including the solar panel kit, batteries, and all the additional parts and wiring needed to complete this part of your van?


Hey John, thanks for this fantastic guide. Seriously, you do an amazing job of explaining how you connected the whole system simply but with enough detail to really understand what is going on. Also, your diagram or the system is super helpful. One question, in other places on your site you mention installing a battery isolater and I didn’t notice anything about in the above article. I am a new van owner and am getting ready to build mine out with a set up very similar to yours but I want an isolater so the batteries will charge from the… Read more »


I have a 1975 Ford Econoline 350 with 85k miles and 5 on a rebuild. I’m at the point where I’ve wire all my 110 for regular inlet and a shore power hookup. How much did you spend on all the solar panels and 12v wiring and plug ins extra?


Thank you. What else to say? Can we donate to you cause – for this is a highly praised resource.
But, I am curious and I can’t quite find a source that clearly states – the charge controller holds the + – solar cables, + – battery, but what did you choose to wire into the + – “Load” slots on your controller?
I’m a little confused on which appliance has priority for that slot, or is it acceptable to leave it empty – if you’d even want to?
Thanks again.


Hilton Homes

Omg! I love your ideas. All of it! Your DIY ideas are awesome. It makes me want to make my own too. Thanks for this creative and awesome DIY ideas!

Matt F
Matt F

How did you mount the dimmer switch? Thanks!


your guide is making my van build doable!! without this i would be seriously struggling and likely have to hire an electrician for help. Thank you!!

question! what is the purpose of the kill switch between the battery and the charge controller? It seems like a hazard if Renogy says that wiring the panels to the charge controller without the battery connected could cause explosion. Seems like an accidental flip of that switch could put your system down.
what was the thought behind this?



also, do you cut power to your inverter when you have nothing plugged into it?


A tip for attaching large battery cables to the sheet metal body, after attaching the lug with a self tapping screw through the hole in the lug, put another self tapping screw through the lug outside of the hole (drill through the lug). This will prevent the lug from rotating and loosening. Be sure to remove the paint from the sheet metal before attaching any high current cables. If installing 120v power outlets, don’t use standard house wiring. Don’t use any solid wire. Use only stranded wire. 3 conductor stranded wire that looks similar to romex is available and makes… Read more »

Andy Goens
Andy Goens

Awesome entry. Probably one of the most thorough yet easy to follow entries on electrical I’ve come across. Quick questions, it looks like the charge controller in your pictures is different than the kitted item in the Amazon solar kit. Did you go a different route personally or is the one in that kit sufficient? Also, I’m stuck in the south so the Alabama heat has an air conditioner in my electrical plans. Have you considered adding a 30A RV shore power connection to plug in on a grid? Not finding as many resources for that. I’m not wanting to… Read more »

Matthew A. Fuentes
Matthew A. Fuentes

First let me say what a great resource this blog post is! So I have come across a problem. I have my inverter and fuse box wired into a marine grade on/off switch (like the ones you have used). The switch allows me to isolate the inverter and fuse box and can also turn on both. The inverter works fine however when I hooked up a test light to the fuse box I got no power. I checked all connections and even bypassed the larger 120 fuse (went straight from switch to fuse box). I am lost!! Help!! I have… Read more »


Question for you guys! I’ve been doing some research on inverters because of high price ($285) of the one listed. I found a 2000W Inverter on amazon and am curious if you see this compatible? We are essentially following your set up, just customizing it. We will be running a Renogy 200W to a 20A Rover MTTP Charge Controller connected to two 12V-155ah VMaxx batteries. This is the inverter we found with double the output for nearly half the price ($140). It comes with a crap charge controller we would obvious ditch for Renogy’s.. but any opinion on this is… Read more »


Great post! Very thorough. I did want to point out something a little confusing. You wrote, “Per the tech specs on our Acegoo 12V recessed LED lights, they have a max current of 3V per light. To convert that to amperage, we divide by the system volume (3V / 12V = 0.25A).” After a little head-scratching, I figured out that I think you mean, that each light draws 3W, not 3V. So your equation should be 3W/12V = 0.25A.

Graci Lee
Graci Lee

Nice system! I did the 400 kit too and it’s worth the peace of mind on long outbacks.
Nice storage solution for the mobile one.
A H5 to adventurevanman for high lighting
The great detail you share .
Q – On your diagram, u have the fuse for the inverter on the neg wire. Shouldn’t it be on the pos wire?
It’s great to see all the instructions in one place !
Thank you !
The Sub-Urban Mama
Converted Suburban 😉

Jack Henry
Jack Henry

all solar set ups i’ve seen so far direct all the working current through the charge controller. If I am planning on adding solar, does it make sense to buy the charge controller now and wire it into the system, so that once I do get the panels i can plug them in and go?


This guide is a lifesaver!!! Thank you so much for this. I have one question: you say you have to connect the batteries to the charge controller before the solar gets connected to it otherwise it might blow up. Does that mean after everything is all connected together, what if for some reason you have to use the kill switch thingy, and stop the current going from the batteries to the charge controller? Would you have to disconnect all the solar panel wiring first?


Since the charge controller is not supposed to be hooked to panels without battery would it make any sense to have the on/off switch instead located between the solar panels and the controller?



Thanks for this. Really help me.

Question. Why you use a 2 awg for ground connection for the batteries. And the red one is 4agw between charge controller and batteries. They doesn’t have to be the same? Same amp (your case 155+155)




Hello! Thank you for all this information!
I am wondering about the whether to put the wiring in before or after insulating our van. We live in Montana and it gets well below zero in the winter. To combat that we will have 5 inches of wool insulation on all sides of the van. Is there any worry about wires freezing, breaking from cold or not working in general, if we install them first?

Brynne Johnson
Brynne Johnson

hi! i am curious as to how you hooked up the fuse box and inverter from the battery. i see a few pictures of the battery but i am curious of the tools and supplies necessary to do so! thanks for all your informative pages 🙂


Hi just wanted to say thank you so much for this guide it has been immensely helpful as I set up my system. Hopefully will be installing this weekend! Check out my progress @kellenbusby.

One quick question. How did you determine the wire size for connecting your batteries to your charge controller? And also, I could be wrong but the battery wire that’s connected to your charge controller in your pictures looks much thinner than 4awg. I’m questioning whether or not 4awg wire will fit in the renogy mppt charge controller.

Thanks so much!


Howdy folks, this page has been such a help in my astro build.
I am running wiring for the lighting, I have the acegoo lights and same dimmer switch as you.
could you give a quick overview on how you ran lighting wiring from your fuse box, bus bar and load?
I have read that these lights need to be wired in parallel, I am looking at soldering T splices to make this happen.
Thanks for all of the knowledge,


Also with your fuse holder on the solar line, How did you go about splicing that? did you have to solder?


Wow! This is the article I’ve been dreaming of! Thanks so much for the totally thorough detail. currently doing the wiring plan for a van I just purchased and this article will really help me out. Haven’t read the whole thing yet so I’ll let you know if I have any questions. Thanks so much.


Hey John! Thank you so, so much for all the work you both have done on the site and on these resources for our community. It’s so hugely helpful, and of course every chance I get, I make my amazon purchases through your links! I read down through many prior comments, but I couldn’t see if this was answered yet: how did you rig your fridge? I assume it isn’t powered through AC via the inverter, so does that mean it’s powered through the fuse box? Or perhaps directly into the battery via one of these guys? https://www.amazon.com/gp/product/B00G8WLW2Y/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1 Just looking… Read more »


Hi John,

Have you had any issues with charging 5v batteries into your 12v USB outlets? An example would be phones, fitbit, gopro, kindle, which from what I have seen all require a 5v power supply.



Thanks for the post. Amazing write up and descriptions. I have a few questions.
1) What’s the wire size you used to connect the inverter to the battery?
2) what’s the wire size you used to grounded the inverter and battery
Thank you guys 🙂

Jonathan Barber
Jonathan Barber

Does this system come work with a split charge relay coming from the alternator?


I’m so confused and not sure you could help because your system seems to be working. So I literally wired everything the exact same way as you, but when it comes time to connect the fuse box, the charge controller reads ERR 4. So I called Renogy and they basically said I’m not supposed to run a fuse box to the charge controller so basically I have no idea what to do because your fuse box seems to be working fine


This is the most detailed and comprehensive post I can find on the internet – thank you! Do you happen to have a wiring diagram for LED lights? In your diagram where it says “to lights etc”, I’m trying to understand the details and how you wired your lights, dimmer, etc. Any help is much appreciated!


I have read this post so many times trying to wrap my head around building an electrical system and I wanted to say thank you so much for putting it out there! We are doing the simplified version of your build out with the battery isolator and maybe a battery charger for when we are around shore power. We also got the Victron BMV-700 to monitor the battery. It seems pretty straightforward the way you guys do it, having everything go through a charge controller but I’m a little confused on what to do if that piece is missing from… Read more »

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