The solar question comes up in almost every consultation. “How much solar do I need?” And the honest answer is: it depends on what you actually do in the van. We’ve seen people install 800 watts of solar they never fully use, and others install 400 watts and regret it constantly. The difference is planning.

Start by Knowing Your Power Consumption

Before you buy a single panel, you need to understand what you’re powering and how much energy it uses. This is the step most people skip, and it’s why they end up with the wrong system.

Make a list of everything that draws power:

Refrigerator: typically 5-10 amps continuous when running (it cycles on and off)
Water heater (if electric): 3000 watts for 10-20 minutes when you run it
Roof vent fan: 5-10 amps on high
LED lighting: 0.5-2 amps per fixture depending on brightness
Phone and laptop charging: 2-5 amps total
Coffee maker or other appliances: varies widely

Add up everything you use on an average day, not your worst-case day. If you’re boondocking in a sunny location, you probably use your van from 6am to 10pm. That’s 16 hours. If you’re in a rainy climate, you might be running fans and heating for 20+ hours.

Calculate Your Daily Amp-Hour Need

Amp-hours (Ah) is the standard measure of battery capacity. If something draws 5 amps for 2 hours, that’s 10 amp-hours consumed.

Let’s say your daily power needs are:

Fridge: 8 amps × 24 hours = 192 Ah
Lighting: 3 amps × 6 hours = 18 Ah
Ventilation: 5 amps × 8 hours = 40 Ah
Charging devices: 3 amps × 4 hours = 12 Ah
Total: roughly 260 Ah per day

That’s moderate consumption. A full-time boondocker might need 400+ Ah. Someone who mostly stays at RV parks with hookups might use 150 Ah.

Understand Your Battery Bank

This is where it gets real. You need enough battery capacity to store energy for cloudy days and nighttime when solar isn’t generating.

Most van builders use lithium batteries (LiFePO4) these days because they’re lighter, charge faster, and last longer than lead-acid. A 100Ah lithium battery costs around $1000-1500. A 200Ah system costs $2000-3000. For a full-time van lifer doing moderate boondocking, 200-300Ah of lithium is standard. For a weekend warrior, 100Ah works fine.

Lead-acid batteries (like traditional car batteries) are cheaper but heavier and less efficient. You’re not getting full capacity from a lead-acid bank - typically only 50% of rated capacity should be used to avoid damaging the battery. So a 200Ah lead-acid battery only realistically gives you 100Ah of usable power. Factor that into your planning.

Sizing Your Solar Array

Here’s the simple formula: your daily power need divided by your average daily sunshine hours.

If you need 260 Ah per day and you’re in a region with 4 hours of average daily peak sun equivalent, you need: 260 Ah ÷ 4 hours = 65 amps of solar production capacity

Solar panels are rated in watts. An amp of production is roughly 10 watts (this varies by voltage, but it’s a reasonable approximation for planning). So 65 amps of production is about 650 watts of installed solar.

In practice, we usually add a buffer. So 800 watts is realistic for that scenario.

A standard 400W solar panel produces about 30-35 amps in ideal conditions. Most van builds have room for 2-3 panels on the roof. That puts you in the 800-1200W range, which covers most van lifers.

Regional Variations Matter

Arizona and California get more winter sun than Oregon and Washington. If you’re planning year-round boondocking in the Pacific Northwest, you might need bigger battery capacity and more solar than the math suggests, because winter production drops significantly.

Conversely, if you’re mostly in sunny regions or using RV parks seasonally, a smaller system is sufficient.

We typically design systems assuming 50-60% of theoretical maximum production, because angle, cloud cover, and panel degradation all reduce real-world output compared to laboratory ratings.

The Basic/Standard/Premium Solar Breakdown

For clients doing full conversions with us:

Basic builds often include 400-600W solar with a 100-150Ah lithium battery. This covers light boondocking and primarily RV park use.

Standard builds get 600-1000W solar with a 200-300Ah lithium battery. This is the sweet spot for people planning real van life who don’t want to compromise on power.

Premium builds typically include 1000W+ solar with 300-400Ah lithium battery and advanced monitoring. This is for people building serious adventure rigs that need to be self-sufficient for weeks.

These aren’t universal rules - they’re guidelines based on what works for most people. Your actual needs might differ.

System Components Beyond Solar

A complete system includes more than panels and batteries:

Charge controller: Manages power from solar panels to battery. PWM controllers are simpler and cheaper; MPPT controllers are more efficient, especially with multiple panels.
Inverter: Converts DC battery power to AC for appliances. Size matters here - a 1500W inverter handles most van appliances, but induction stoves and hair dryers need more.
Monitoring system: A display showing battery percentage, solar production, and loads. Essential for understanding if your system is sized correctly.
Wiring and breakers: Properly sized wire and overcurrent protection. Undersized wiring causes fires. This isn’t an area for DIY guessing.

The Oversizing Debate

Some people install way more solar than they need “just in case.” The downside is cost and weight. A 1500W system on a small van costs $3000-4000 installed and adds significant weight. If you only need 600W, that’s wasted money you could spend on a better bed, nicer kitchen, or extra battery capacity.

We recommend sizing to your realistic use case, then planning what you’d add if your needs change. A roof rack with extra mounting points costs $500 upfront. Adding panels later costs $1500-2000 per panel because you’re doing retrofit work.

Monitoring Over Time

Once your system is installed, pay attention to it. Check your battery percentage daily, especially during winter or cloudy stretches. If you’re regularly hitting 20% battery at dinner time, you need more solar or need to reduce consumption. If you’re always topping out at 100%, you’re oversized (which isn’t the end of the world, but it’s money not optimized).

We include monitoring system setup in all our Standard and Premium builds, so clients can actually see what’s happening with their power.

Getting the Design Right

Solar sizing isn’t something to guess on. We work through this calculation with every client during the design phase. We want your system to work for how you actually live, not force you into compromises because the system’s undersized.

If you’re planning a conversion or upgrading an existing system, let’s talk through your power needs. We can help you size a system that actually works for your van life style.

Van Life Solar: How Much Power?