Why Solar Makes Sense for Overlanding
On a weekend trip, you can probably get by charging everything off the alternator while you drive. But the moment you're spending consecutive days at camp — or traveling through remote areas where you're driving short distances between stops — alternator charging isn't enough. A 12V fridge draws 3-5 amps, a phone charger pulls 2 amps, LED lights run another amp or two. Over a 24-hour camp day, that's 80-120 amp-hours of draw. Your auxiliary battery is dead by morning.
Solar solves this quietly, reliably, and with zero fuel cost. A properly sized system replenishes what you use each day, keeping your batteries in the sweet spot and your fridge running indefinitely. For a deeper look at ready-made options, check our best solar setups for overlanding.
Panel Types: Monocrystalline vs. Polycrystalline vs. Flexible
Monocrystalline panels are the gold standard for overlanding. They're the most efficient per square foot (typically 20-22% efficiency), meaning more watts in less space. They perform better than poly panels in partial shade and low-light conditions. Virtually every quality roof-mounted or portable panel uses monocrystalline cells.
Polycrystalline panels are cheaper but less efficient (15-17%). They're larger for the same wattage and perform worse in heat and partial shade. For overlanding, where roof space is at a premium, poly panels rarely make sense. They're fine for a cabin or a base camp where size isn't a constraint.
Flexible panels are thin, lightweight, and can conform to curved surfaces like a pop-top roof or a canopy. The trade-off is significant: they're less efficient, degrade faster (especially with heat buildup since they can't ventilate), and most can't be walked on. I've seen flexible panels on canopy roofs start delaminating after 18 months of UV exposure. Use them where rigids won't fit, but expect a shorter lifespan.
Fixed vs. Portable Panels
This decision depends on how you camp.
Fixed roof-mounted panels are always collecting energy — while you drive, while you're at camp, while you sleep. You don't have to set anything up or worry about theft. The downside: they can't be angled toward the sun, so you lose efficiency when the sun isn't overhead, and they take up roof space that could be used for other gear. A 200W panel on a roof rack produces maybe 120-140W in realistic conditions due to angle losses, partial shading from roof gear, and heat.
Portable panels can be angled toward the sun for maximum output, placed in full sun while your vehicle sits in shade. They're versatile and can be shared between vehicles. The downside: you have to deploy them at every stop, they can be stolen, and they're one more thing to pack. In windy conditions, they need to be secured or they'll blow over.
My setup uses both: a 200W fixed panel on the roof for passive charging, and a folding 120W portable panel for camp stops where I need extra input. For travelers who want simplicity, an all-in-one portable power station like the Jackery Explorer 1000 paired with its matching solar panels offers a plug-and-play solution that requires zero wiring knowledge.
Charge Controllers: PWM vs. MPPT
The charge controller sits between your panels and your battery, regulating voltage and current to charge safely.
PWM (Pulse Width Modulation) controllers are cheap ($20-50) and simple. They work by matching the panel voltage to the battery voltage, which wastes the excess voltage as heat. A 100W panel through a PWM controller might deliver 70-75W to the battery. They're fine for very small systems (under 100W) or budget builds.
MPPT (Maximum Power Point Tracking) controllers are more expensive ($80-300) but significantly more efficient. They convert excess voltage into additional current, extracting 15-30% more energy from the same panel compared to PWM. A 100W panel through an MPPT controller delivers 90-95W to the battery. For any system over 100W, MPPT pays for itself quickly.
Get an MPPT controller. The efficiency difference adds up fast, and a quality unit like a Victron SmartSolar or Renogy Rover also provides Bluetooth monitoring so you can see exactly what your system is producing and consuming from your phone.
Sizing Your System
Start with your daily power consumption, then size panels to match.
Step 1: Calculate daily draw.
- 12V fridge (50L): 3-5 amps average = 40-60 Ah/day
- Phone charging (2 phones): 2 amps x 4 hours = 8 Ah/day
- LED lights: 1.5 amps x 4 hours = 6 Ah/day
- Laptop charging: 5 amps x 2 hours = 10 Ah/day
- Miscellaneous (fan, USB devices): ~10 Ah/day
Total: roughly 75-95 Ah/day for a typical overlanding setup.
Step 2: Calculate solar input. A 100W panel produces about 5-6 amps in full sun. Over 5-6 peak sun hours (a reasonable average for summer in the lower 48 or Australia), that's 25-36 Ah per day. So for 90 Ah of daily draw, you need roughly 250-350W of panel capacity. I'd aim for 300W as a practical target for most setups.
Step 3: Size your battery bank. Your battery bank should hold at least 1.5-2x your daily draw to avoid deep discharges. For a 90 Ah daily draw, a 200 Ah lithium battery bank is ideal. AGM batteries should only be discharged to 50%, so you'd need 180-200 Ah of AGM capacity for the same usable energy. See our comparison of lithium vs AGM batteries for more on choosing battery chemistry.
Wiring Basics
Solar wiring isn't complicated, but undersized wire causes voltage drop, heat, and lost efficiency.
Use the following minimums for 12V systems:
- Panel to controller: 10 AWG for runs under 15 feet, 8 AWG for longer runs
- Controller to battery: 8 AWG minimum, 6 AWG for systems over 200W
- Fuse at the battery: Always. Size the fuse for the maximum controller output current, plus 25%
All connections should use marine-grade tinned copper ring terminals, crimped (not soldered — solder wicks and creates a stress point) and covered with adhesive-lined heat shrink. Invest in a proper ratcheting crimp tool — it costs $30 and pays for itself in reliable connections that don't fail from vibration.
All-in-One Power Stations
If wiring a custom system sounds like more than you want to take on, portable power stations have gotten remarkably capable. The Jackery Explorer 1000 delivers 1,000 Wh of lithium storage with built-in inverter, charge controller, and multiple output ports. Pair it with a matching solar panel and you have a complete off-grid power system with zero wiring.
The trade-off versus a custom system: less capacity per dollar, less expandability, and you're replacing the whole unit if one component fails. But for overlanders who want reliable power without becoming electricians, they're excellent. Check our best solar setups guide for current recommendations across all price points.
Common Mistakes
- Undersizing the system — a 100W panel cannot keep a fridge and devices running. Size for reality, not ideal conditions.
- Ignoring shade — parking under a tree cools the vehicle but kills solar output. Even partial shade from a single branch reduces panel output dramatically with series-wired panels.
- No fusing — an unfused connection between battery and charge controller is a fire risk. Fuse everything.
- Mixing battery chemistries — don't connect AGM and lithium batteries in the same bank. Different charge profiles cause overcharging or undercharging.