RV Solar System Basics: What Every Owner Should Know

Solar is one of the best upgrades you can make to an RV. But the terminology, component choices, and wiring requirements confuse a lot of people. This is a plain-English overview of how RV solar works, what the components do, and how to think about sizing a system for your needs.

The Four Basic Components

1. Solar Panels

Panels collect sunlight and produce DC electricity. RV panels are typically 100W to 200W each. They come in two main types: monocrystalline (more efficient, better in partial shade) and polycrystalline (slightly cheaper, slightly less efficient). For most RV applications, monocrystalline is worth the small price difference.

Panels are rated in watts under ideal conditions. Real-world output is usually 70–80% of the rated wattage due to heat, angle, and atmospheric factors.

2. Charge Controller

The charge controller sits between the panels and the battery bank. Its job is to regulate the voltage and current coming from the panels so it charges your batteries correctly without overcharging or damaging them.

There are two types: PWM (Pulse Width Modulation — cheaper, less efficient) and MPPT (Maximum Power Point Tracking — more expensive but extracts significantly more power, especially in cooler weather or partial shade). If you’re investing in solar, use an MPPT controller.

3. Battery Bank

The battery bank stores the energy collected during the day for use at night or during cloudy weather. Your battery choice makes a huge difference:

• Flooded Lead-Acid — Cheapest upfront, require maintenance (watering), heavy, limited to 50% depth of discharge
• AGM (Absorbed Glass Mat) — Sealed, no maintenance, better than flooded but still limited depth of discharge
• Lithium (LiFePO4) — Expensive upfront but usable to 80–100% depth of discharge, much lighter, longer lifespan (10+ years vs 3–5). The best choice for full-time or frequent RV use.

4. Inverter (Optional)

If you want to run AC appliances (microwave, TV, CPAP) from your battery bank, you need an inverter to convert 12V DC to 120V AC. See our Converter vs. Inverter guide for more detail.

How to Size a System

The basic formula is: figure out how much power you use per day (in watt-hours), then build a battery bank that can hold 2–3 days of that usage, then size the panels to refill the battery bank in one good sun day.

Common Solar Mistakes

• Undersized wiring — Solar wiring that’s too thin creates resistance, heat, and power loss. Use the correct gauge for the run length and current.
• PWM controller with lithium batteries — PWM controllers don’t work well with lithium chemistry. Use MPPT.
• Panels in partial shade — One shaded panel can cut output of the entire string dramatically. Plan your panel placement carefully.
• No battery monitor — Without a proper battery monitor (like a Victron BMV-712), you’re guessing at your state of charge. This leads to over-discharging and premature battery failure.