RV Solar Panel Setup Guide - Sizing, Wiring and Installation

Solar lets you camp anywhere without hookups. No generator noise, no campground fees, no extension cords. But sizing it wrong means dead batteries by 9 PM.

System Components

Every RV solar setup has four parts:

1. Solar panels — convert sunlight to electricity
2. Charge controller — regulates voltage to protect batteries
3. Battery bank — stores the energy
4. Wiring — connects everything together

Optional: an inverter to run AC appliances from battery power.

Sizing Your System

Step 1: Calculate Daily Usage

List everything you run on 12V and estimate daily amp-hours:

Device	Amps	Hours/Day	Ah/Day
LED lights	2A	5h	10 Ah
Water pump	4A	0.5h	2 Ah
Fridge (12V)	5A	8h	40 Ah
Phone/laptop charging	2A	3h	6 Ah
Vent fan	1A	8h	8 Ah
Total			66 Ah

Step 2: Account for Inefficiency

Multiply by 1.2 for system losses (wiring, controller, temperature). That gives you about 80 Ah needed daily.

Step 3: Size the Panels

A 100W panel produces roughly 30 Ah per day in good Texas sun (5-6 peak sun hours). For 80 Ah daily need, you want about 300W of panels.

Rule of thumb: 100W of solar per 30 Ah of daily consumption.

Step 4: Size the Battery Bank

Lead-acid batteries should only discharge to 50%. So 80 Ah daily use needs a 160 Ah lead-acid bank.

Lithium batteries discharge to 80-90%. The same 80 Ah use only needs a 100 Ah lithium bank. More expensive upfront but lighter and longer-lasting.

Charge Controller Types

PWM (Pulse Width Modulation)

• Cheaper ($20-80)
• Less efficient (75-80%)
• Panel voltage must match battery voltage
• Fine for small systems under 200W

MPPT (Maximum Power Point Tracking)

• More expensive ($100-400)
• More efficient (92-98%)
• Handles higher panel voltage — converts excess voltage to amperage
• Required for systems over 200W

MPPT controllers harvest 15-30% more energy from the same panels. On a 400W system, that’s an extra 60-120W of usable power daily. The controller pays for itself in panel savings.

Series vs Parallel Wiring

Parallel: Voltage stays the same, amperage adds up. Each panel works independently — shade on one panel doesn’t affect others. Better for RVs with partial roof shading.

Series: Amperage stays the same, voltage adds up. Higher voltage means less current through wires, allowing thinner gauge cable. But shade on one panel reduces the entire string.

Best approach for most RVs: Wire panels in parallel with an MPPT controller. You get shade tolerance and the MPPT controller efficiently converts the power regardless.

Installation Steps

Roof Mounting

1. Clean the roof surface
2. Mark panel positions (leave 2” gaps for airflow)
3. Apply Dicor self-leveling sealant to mounting feet
4. Screw mounts through the roof into structural supports
5. Seal every screw hole with Dicor — water leaks ruin RVs
6. Route cables through a weatherproof entry plate

Wiring

1. Use 10 AWG wire minimum for runs under 20 feet
2. Install MC4 connectors for panel connections
3. Run positive and negative wires together to reduce interference
4. Install a breaker or fuse between panels and controller
5. Install a breaker between controller and battery bank

Charge Controller Placement

Mount the controller inside, close to the battery bank. Short wire runs between controller and batteries minimize voltage drop. Keep it ventilated — controllers generate heat under load.

Texas Solar Performance

DFW gets 5-6 peak sun hours daily from March through October. Winter drops to 3.5-4.5 hours. Size your system for winter if you camp year-round, or add a portable panel you can angle toward the sun.

Texas heat actually reduces panel efficiency. Panels lose about 0.4% output per degree above 77°F. On a 100°F day, expect 10-15% less output than rated. Factor this into your sizing.

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