The Complete RV Solar and Battery Upgrade Guide

Shore power hookups are fine when you can get them. But the campgrounds with hookups are often the crowded, noisy ones. The sites you actually want — dispersed BLM land, national forest roads, remote state parks — don’t have pedestals. A solar and lithium upgrade changes what’s possible: leaving the generator off, staying in any site you want, and running your normal loads without watching a battery gauge creep toward empty.

Start With Your Loads

Before any component decisions, you need to know what you’re powering and how much energy it uses each day.

Typical daily totals: Weekend van or small trailer: 400–900 Wh/day. Mid-size trailer or Class B: 1,000–1,600 Wh/day. Class C or 5th wheel, no A/C: 1,500–2,500 Wh/day. Class A or full-timer with heavy loads: 3,000–6,000+ Wh/day. If you don’t have an exact number, budget 1,200 Wh/day for a mid-size rig without air conditioning.

The Four Core Components

1. Battery Bank

LiFePO4 is the right choice for almost every RV upgrade. Compared to AGM: roughly half the weight for the same usable capacity, nearly 100% of rated capacity is usable (vs ~50% for AGM), charges faster from solar, and lasts 3–5x longer in cycle life. The weight difference alone is significant — replacing two 100Ah AGM batteries (~130 lbs) with 100Ah LiFePO4 (~30 lbs) frees up 100 lbs for fresh water, gear, or nothing.

Sizing: Aim for 1.5–2x your daily energy use for a full day of autonomy plus a buffer. For a 1,200 Wh/day rig, target 200–250Ah at 12V.

2. Solar Panels

Roof space is your constraint. Most rigs can fit 400–800W of rigid panels. The sizing formula: Daily Wh ÷ Peak Sun Hours ÷ 0.8 = Required panel watts. For 1,200 Wh/day at 5 peak sun hours: 300W minimum. Rigid monocrystalline panels are the standard for RV roofs — more efficient per square foot and longer-lasting than flexible panels.

3. MPPT Charge Controller

Always use MPPT, not PWM. MPPT extracts 15–30% more energy from the same panels. The Victron SmartSolar MPPT line is what we install: the 100/30 handles up to ~400W at 12V, the 100/50 up to ~700W, the 150/70 and 150/100 for larger arrays. Built-in Bluetooth means you can monitor production and battery state from your phone.

4. Inverter or Inverter-Charger

If you’re running AC loads, you need an inverter. An inverter-charger makes sense for most RV upgrades — when you pull into a campground with hookups, it detects shore power and begins charging automatically. Disconnect, and it switches back to battery seamlessly. Victron’s MultiPlus-II is the most common choice, available from 1,200W up through 5,000W. For most mid-size rigs, the 12/2000 or 12/3000 covers common AC loads well.

Three System Levels

Starter — Weekend Boondocker: 100–200Ah LiFePO4, 200–300W solar, Victron SmartSolar MPPT 100/20 or 100/30, 1,000–2,000W inverter. Covers a fridge, lights, devices, and a fan for 1–2 nights without hookups.

Mid-Range — Regular Off-Grid: 200–300Ah LiFePO4, 400–600W solar, Victron SmartSolar MPPT 100/50, Victron MultiPlus-II 12/2000 or 12/3000. Adds laptop use, larger fridge, CPAP, TV, and modest cooking loads.

Serious Boondocker — Extended Off-Grid: 300–600Ah LiFePO4, 600–1,000W+ solar, Victron SmartSolar MPPT 150/70 or 150/100, Victron MultiPlus-II 12/3000 or 24/3000, Cerbo GX for centralized monitoring. Built for full-timers and those measuring days off-grid and finding the number too low.

Don’t Overlook the Battery Monitor

A shunt-based battery monitor like the Victron SmartShunt gives you real-time data on watts in, watts out, state of charge, and days of remaining runtime. Install it from day one and you’ll always know exactly where you stand.

Browse the full solar panel, lithium battery, charge controller, and inverter-charger collections at Blue Marine, or schedule a free system consultation with our team.

Related reading:
How to Size a Battery Bank for Your RV: A Practical Guide
LiFePO4 vs AGM Marine Battery: Which Should You Buy?
Victron MultiPlus-II Sizing Guide: Which Model Do You Need?