9 RV Solar Panel Installation Mistakes

Every new RVer has the same dream: solar panels on the roof, the fridge running, phones charging, and no need to fight for a campsite with shore power.

Then reality hits. The system produces less power than expected. The charge controller acts up. Or worse, rain finds its way through a poorly sealed roof hole.

Most of these problems are avoidable. Before you start drilling, wiring, or buying parts, watch out for these common RV solar panels installation mistakes.

Part One: Cooling and Mounting Mistakes

Mistake 1: Mounting solar panels with no airflow underneath

Some RV owners stick flexible solar panels directly to the roof or bolt rigid solar panels down with no gap underneath. The problem is heat. On a summer day, solar panels can get well above 150°F. When heat gets trapped, output drops and long-term wear speeds up.

What to do instead:  

Give the solar panels room to breathe. Rigid solar panels should sit on mounting brackets with an air gap underneath. For flexible solar panels, follow the manufacturer’s instructions. If the solar panel allows it, use mounting strips, spacers, or a raised backing surface to create airflow channels.

Mistake 2: Assuming flat mounting is always best

Flat-mounted solar panels are simple and common, but they rarely deliver maximum output. The best angle changes with your location, season, and sun position. What works in Arizona may not work as well in Montana or Alaska.

What to do instead:  

If you stay parked for several days, especially in winter or at higher latitudes, tilt mounts can help. A common starting point is to tilt solar panels close to your latitude. If you move often, flat mounting may be more practical. Flexible solar panels are usually chosen for low-profile, lightweight, or curved-roof installs—not for adjustable tilt.

Mistake 3: Poor sealing after drilling into the roof

Roof leaks often start at bracket holes or cable entry points. Household silicone is not a good choice for RV roofs. UV exposure, vibration, and temperature changes can cause it to crack or peel.

What to do instead:

Use RV roof sealant made for the surface. On most horizontal RV roofs, self-leveling lap sealant is common. For vertical surfaces or raised cable entry boxes, non-sag sealant may work better. Clean the area before sealing, check the cure time on the label, and consider using a raised roof gland for cable entry.

Part Two: Electrical and Wiring Mistakes

Mistake 4: Using undersized cables

Thin cables can cause voltage drop, especially on long runs from the roof to the charge controller. That means less power reaches your battery. Undersized wire can also run hot, which creates a safety risk.

What to do instead:  

Size cables based on current and round-trip distance. Use an AWG wire chart or voltage-drop calculator. When in doubt, go one size thicker. Also use proper fuses or breakers near the power source.

Mistake 5: Choosing the wrong charge controller

A controller labeled “12V/24V compatible” is not enough. For an MPPT controller, estimate output current by dividing total solar wattage by battery voltage, then add a safety margin. For example, an 800W array charging a 12V battery bank can produce around 65–70A, so an 80A controller is usually the minimum to consider.

You also need to check the controller’s maximum PV input voltage and wattage, especially with panels wired in series.

What to do instead:  

Do the math before buying. Leave at least a 25% buffer when possible. After installation, set the correct battery type. Many controllers ship with lead-acid defaults, which may not work properly for LiFePO4 batteries.

Mistake 6: Connecting the system in the wrong order

Many charge controllers need to see battery voltage before solar input. If you connect the panels first, the controller may fail to initialize correctly or even be damaged.

What to do instead:  

Connect the battery first, then the solar panels. When disconnecting, reverse the order: panels first, then battery. If possible, cover the panels or turn off the PV breaker before working on the wiring.

Part Three: Planning and Layout Mistakes

Mistake 7: Placing panels where roof equipment casts shadows

AC units, vents, antennas, and roof racks can all cast shadows. In a series string, even one shaded panel can reduce the output of the whole array. Partial shading can also create hot spots over time.

What to do instead:  

Do a dry-fit before drilling. Place the panels on the roof and watch how shadows move during the day. If shading is hard to avoid, parallel wiring can reduce the impact, but it increases current—so wire size and fusing matter even more.

Mistake 8: Buying a system before calculating your power use

A 200W kit may look fine online, but it may not keep up with a fridge, water pump, lights, fans, and phone charging. The problem is not always the panel. Sometimes the system is simply too small.

What to do instead:  

List your devices, their wattage, and how many hours you use them each day. Add them up in watt-hours. As a rough estimate, daily solar production is often:

panel watts × peak sun hours × 0.7

That 0.7 helps account for heat, angle, wiring loss, dust, and real-world conditions.

Mistake 9: Expecting solar to power everything forever

Solar helps you boondock longer, but it is not unlimited power. Clouds, shade, winter sun, and short daylight hours can cut production sharply. Two cloudy days can push a small system to its limit.

High-draw appliances are another issue. Air conditioners, microwaves, induction cooktops, and electric heaters can drain batteries fast unless you have a large solar array and a serious battery bank.

What to do instead:  

Treat solar as a way to extend battery runtime, not replace every power source. Size your battery bank for at least a couple of low-sun days, and keep realistic expectations.

Before You Start

Get three things right before installation:

1. Know your power use. Big fridges and heavy loads need more solar and more battery.

2. Know your roof. Check structure, drilling spots, cable routes, and shadows before mounting.

3. Follow the correct electrical sequence. Battery first, panels second. Set the controller for your actual battery type.

If you are not comfortable with roof work or electrical wiring, hire a professional RV shop. Paying for a clean installation once is cheaper than fixing leaks, replacing damaged equipment, or troubleshooting a system that never works the way it should.

You might want to know: Why Do Some Outdoor Solar Panels Stay Durable For Years