Free DIY Guide

RV Solar Installation

System sizing, roof panel mounting, MPPT charge controller wiring, battery bank setup, and getting real monitoring so you know your state of charge.

A Geek designs the system, handles the roof mount and Dicor sealing, wires the controller and battery bank, and leaves you with a working solar setup and a monitoring app. From $299.99.

I'll install it myself ↓

4--8 hours

Advanced

Fusing and Dicor sealing are non-negotiable

The Z-bracket holes are sealed with silicone. Not Dicor. Silicone and EPDM roof membrane are incompatible. The roof is now delaminating. This was a $6,000 mistake.

Before you drill or connect anything:

•Every roof penetration -- Z-bracket bolts, cable entry glands -- MUST be sealed with Dicor lap sealant. Apply two coats. Roof leaks from unsealed solar mounts are one of the most common and costly RV repair claims.
•Wire polarity cannot be wrong. Battery positive to positive, negative to negative. Reversing polarity at the charge controller will destroy it instantly and may damage the battery. Double-check before connecting.
•Install the ANL fuse between the battery positive terminal and everything else. This fuse is the only protection against a short-circuit fire. A system without this fuse is a fire risk, not a solar system.
•Do not connect lithium batteries to a charge controller set for AGM profile, and vice versa. Wrong charge voltage damages AGM and may trigger lithium BMS lockout. Verify controller battery type setting before first charge.
•Never run high-current battery cables -- especially from the battery to the inverter -- without proper fusing. An unfused 2 AWG cable from a 200Ah battery can carry thousands of amps in a short circuit. The cable melts. Then something else catches fire.

What you'll need

The Victron SmartSolar charge controller with the VictronConnect app turns a black-box solar system into a measurable, manageable one.

Solar panels -- rigid or flexible (200W--400W typical starter system)Find on Amazon

Rigid monocrystalline panels (Renogy, Rich Solar, Newpowa) mounted on Z-brackets are the most efficient and longest-lasting option. Flexible panels (SunPower cells) work on curved RV roofs where rigid panels won't lay flat -- they adhere with VHB tape or contact adhesive. Flexible panels are 15--20% less efficient and generate heat under the panel that can degrade the roof membrane over time. Rigid panels elevated on Z-brackets let air flow underneath, run cooler, and last longer.

MPPT charge controller (Victron SmartSolar 100/30 or equivalent)Find on Amazon

An MPPT (Maximum Power Point Tracking) charge controller extracts 20--30% more power from the same panels compared to a PWM controller -- it's worth the extra cost. The Victron SmartSolar series is the gold standard: excellent BT monitoring via the VictronConnect app, configurable charging profiles for lithium or AGM, and a proven 10+ year track record. Size: for 400W of panels into 12V, a 30A controller is sufficient. For 600W+, go to 40--50A.

Battery bank -- AGM or lithium (100Ah--200Ah typical starter)Find on Amazon

If you have existing AGM batteries, a solar system charges them fine. Lithium (LiFePO4) batteries cost more but offer 80% usable capacity vs 50% for AGM, lower weight, 10x more cycles, and faster charging. Renogy, Ampere Time, and Battle Born are commonly recommended brands for RV LiFePO4. If you have lithium batteries, your charge controller MUST have a lithium charging profile (Victron does).

Z-brackets for panel mounting (4 per rigid panel)Find on Amazon

Z-brackets are the standard way to mount rigid solar panels on an RV roof. They elevate the panel 2--3 inches above the roof surface, allowing air circulation to cool the panels. Each bracket mounts through the roof with a stainless steel lag bolt into the roof decking; the hole and surrounding area are sealed with Dicor. Four Z-brackets per panel, typically 6" or 8" legs.

RV solar cable entry gland + 10 AWG stranded copper wireFind on Amazon

The wire from the roof panels into the RV charge controller runs through a weatherproof solar cable entry gland -- a two-port rubber fitting that provides a sealed entry for positive and negative leads. Use 10 AWG copper stranded wire for panel-to-controller runs under 20 feet. Longer runs or higher-current systems need heavier gauge to avoid voltage drop.

ANL fuse or MIDI fuse holder (40A--150A) between battery and charge controllerFind on Amazon

A large-format fuse between the battery and charge controller protects against a short circuit in the wiring. The fuse must be within 18 inches of the battery positive terminal. Size the fuse at 125% of maximum charge controller output current -- a 30A controller gets a 40A ANL or MIDI fuse. Without this fuse, a wiring fault can cause a battery fire.

The steps

6 steps. Step 1 (system sizing) determines whether everything else makes sense. Don't skip it.

Size your solar system -- panels, controller, and battery

Solar system design starts with calculating how much energy you consume per day and working backward to the panel and battery capacity you need. Skipping this step means either an undersized system that leaves you without power or an oversized system that cost more than necessary. Calculate your daily consumption: list every 12V and 120V device you run off the battery (not shore power), its power draw in watts, and how many hours per day you run it. Example: 12V TV (35W) x 3 hours = 105Wh. LED lighting (30W) x 4 hours = 120Wh. Fan (25W) x 8 hours = 200Wh. Laptop charging (65W) x 2 hours = 130Wh. Total = 555Wh/day. Battery capacity: for lithium (LiFePO4) batteries at 80% usable depth of discharge, 555Wh requires at least 694Wh of capacity -- roughly 58Ah at 12V. Round up to a 100Ah lithium battery with comfortable margin. For AGM at 50% usable DOD, you need twice as much: 116Ah of battery for the same daily consumption. Solar panel sizing: panels generate roughly their rated watts only at solar noon in ideal conditions. In real conditions, average 4--5 "peak sun hours" per day in most of the US (lower in the Pacific Northwest, higher in the Southwest). For 555Wh/day at 5 peak sun hours with a 90% efficiency factor: 555 / 5 / 0.9 = 123W of panels minimum. Double that for comfortable margin and cloudy days: 200--300W. Charge controller sizing: for a 12V system, divide total panel wattage by battery voltage for maximum output current. 300W / 12V = 25A. A 30A MPPT controller handles 300W comfortably and gives room for future expansion. Write these numbers down before buying anything: target daily Wh, battery capacity in Ah, panel wattage, and charge controller amperage. This single step prevents the most common and expensive solar installation mistakes.

Pro tip: When in doubt, oversize the battery more than the panels. Adding panels later is easy (the controller and wiring can usually handle more). Adding battery capacity requires replacing or paralleling the existing bank -- which means more wiring work. A 200Ah lithium bank running 200W of panels is a better starting point than 400W of panels with 100Ah of battery.

Mount the solar panels on the RV roof

RV roof mounting is the most physically demanding part of the installation and the most consequential for water integrity. Everything on the roof must be sealed correctly. Rigid panels with Z-brackets: position the panels on the roof first -- make sure they clear the A/C unit, vent fans, and roof vents with at least 4 inches of clearance. Panels should not shade each other. Lay out the bracket positions (one bracket at each corner of the panel, typically 6--8" from the panel edge). Mark all mounting hole positions. Drilling: drill pilot holes at each bracket location. Before drilling, tap the roof surface and listen for hollow vs. solid -- you want to hit roof decking, not just membrane and foam. Use a drill bit slightly smaller than the lag bolt. Sealing the holes: before inserting the lag bolts, put a bead of butyl tape under each bracket foot. Drive the lags in -- snug but not overtightened. Then apply Dicor self-leveling lap sealant over every bolt head and around the full perimeter of each bracket foot. Two coats minimum. Let the first coat skin before applying the second. Cable routing from panels: MC4 connectors (the standard solar panel connector) link panels together and to the cable run going into the roof. The cable run enters the RV through a solar cable entry gland -- a two-port rubber fitting sealed with Dicor, just like every other roof penetration. Flexible panels on curved roofs: flexible panels bond directly to the roof surface using VHB tape (3M 5952 is the spec for this application) or a thin layer of contact cement on flexible substrates. Clean the roof surface with alcohol wipes, let it dry completely, apply VHB tape or contact cement, position the panel, and press firmly. No penetrations needed for the panel itself -- the cable still enters through an entry gland. After installation: walk the entire roof area and verify every penetration is sealed. Take photos of the roof with every Dicor application documented -- if you sell the RV or need a warranty claim, this documentation matters.

Pro tip: Do not install panels in direct sun when it's hot. Hot panels are at open-circuit voltage (Voc) which can exceed 20V for a single 12V panel or 40V for two in series. That voltage is not dangerous, but the panels are slippery when warm and the roof surface is uncomfortably hot to kneel on. Install early morning when the panels are cool and the roof temperature is manageable.

Wire the panels to the charge controller

The wiring from the roof panels to the charge controller inside the RV is a direct current circuit. Wire sizing, fusing, and connector quality matter for efficiency and safety. Panel configuration -- series vs. parallel: in a 12V system, connecting panels in parallel (positive to positive, negative to negative) keeps the voltage at 12--20V nominal and doubles the current. Connecting in series doubles the voltage. Most 12V RV systems run panels in parallel to keep voltage within the MPPT input range of a 12V charge controller (typically 12V--100V input). Check your controller's specifications before wiring panels in series. Wire sizing: from the panels to the charge controller, use 10 AWG copper stranded wire for current up to 30A on runs under 20 feet. For runs over 20 feet or higher currents, move to 8 AWG. Undersized wire means voltage drop and heat. Fusing the panel wire: install an in-line fuse on the positive wire from the panels, sized at 125% of short-circuit current (Isc). For a single 200W panel with Isc of 10A, use a 15A fuse. This is located close to the panels (under the entry gland on the inside, within 18 inches of where the wire enters the vehicle). Entry gland to charge controller: route the solar wires along the ceiling or wall to the charge controller location. Use cable clips to secure at 12" intervals -- no dangling wire that can vibrate and abrade. Keep solar wires separated from AC wiring by at least 4 inches. At the charge controller: the Victron SmartSolar has labeled terminals: PV+, PV-, BAT+, BAT-. Connect the panel wires to the PV terminals first (the controller needs to see panel voltage before battery voltage for some models -- check the manual). Then connect the battery wires. Verify before connecting batteries: use a multimeter to measure the open-circuit voltage at the charge controller's PV terminals (disconnect from controller first). You should read Voc of your panels (typically 20--24V for a 12V nominal panel) on a sunny day. This confirms polarity and continuity before live connection.

Pro tip: Label every wire before you close anything up: red positive wires get a label that says what they're from and where they go. Same for black negative wires. "SOLAR PANEL 1 +" and "MPPT CONTROLLER PV+" on opposite ends of the same wire. Solar wiring in an RV is not complicated, but when something stops working two years from now and you're troubleshooting in a cramped utility bay, labeled wires save hours.

Wire the charge controller to the battery bank

The charge controller to battery connection is where the energy actually flows. This wiring carries the most continuous current in the system and must be sized and fused correctly. Wire sizing: between charge controller and battery, use 8 AWG or 6 AWG wire depending on controller output current. For a 30A controller, 8 AWG is the minimum; 6 AWG provides lower voltage drop. Keep this run as short as practical -- 3 feet or less if the controller and battery are close together. Fusing: install an ANL or MIDI fuse on the positive wire between the charge controller and battery, within 18 inches of the battery positive terminal. For a 30A controller, a 40A fuse. This protects against a short circuit that could cause a battery fire. This fuse is mandatory -- do not skip it. Connecting to the battery: if you have a single battery or a parallel battery bank with a common positive and negative bus, the charge controller connects to the bus. Make sure the bus connections are clean, the terminal bolts are torqued (8--10 ft-lbs for a standard battery terminal), and there's no corrosion. Torque loose terminals are a fire risk. Lithium battery specifics: LiFePO4 batteries have a BMS (Battery Management System) that protects against overcharge and over-discharge. The BMS needs to be compatible with the charge controller's output. The Victron MPPT with a lithium charge profile charges to 14.2V absorption and 13.5V float -- within the BMS tolerance range of all major RV LiFePO4 batteries. Connect the BMS "smart" port to the Victron via a VE.Direct cable for cell-level monitoring if your battery supports it. AGM battery specifics: AGM batteries charge to 14.4--14.8V absorption and 13.6V float -- settings available in the Victron charge controller's battery profile. Do not use lithium settings on AGM batteries -- the higher absorption voltage damages AGM cells. First charge cycle: after all wiring is complete, connect the batteries and power on the charge controller. Watch the VictronConnect app on your phone (connect via Bluetooth). You should see: PV input voltage (panel voltage), battery voltage, and charge state (bulk, absorption, or float). Verify the charge current is positive and the battery voltage is rising. If anything looks wrong -- no current, wrong voltage, error codes -- disconnect and recheck wiring before proceeding.

Pro tip: Take a photo of every wiring connection in the charge controller and battery area before you close the cabinet. If your RV needs electrical work later, having a clear photo of the original wiring saves the technician significant time and protects you from someone rewiring your system incorrectly. Store the photo in a shared album with a note that says "RV solar wiring as of [date]."

Configure the battery bank -- parallel wiring for more capacity

If you're installing more than one battery, they connect in parallel to increase capacity while keeping voltage at 12V. Parallel battery banks require correct wiring to ensure balanced charging and discharging across all batteries. Parallel connection basics: in a parallel battery bank, positive terminals connect to positive terminals and negative terminals connect to negative terminals. This doubles (or triples, etc.) the amp-hour capacity. Voltage stays at 12V. A two-battery parallel bank of 100Ah each gives you 200Ah total at 12V. The diagonal cross-connect method: when wiring two or more batteries in parallel, use the diagonal wiring method to ensure balanced current flow. For two batteries: connect the positive terminal of Battery 1 to the positive bus, and the positive terminal of Battery 2 to the positive bus with equal-length wires. Connect the negative terminal of Battery 1 (the one diagonally opposite your positive draw point) to the negative bus. This balances the current path through both batteries equally. Unbalanced wiring causes one battery to cycle more than the other, shortening the bank's lifespan. Wire sizing for parallel banks: the interconnect wires between batteries in the bank carry the full load current. Size them at least as large as the charge controller output wire -- typically 4 AWG or 2 AWG for a two-battery bank. All interconnect wires in a parallel bank should be the same length. Lithium batteries in parallel: LiFePO4 batteries from the same manufacturer and same production batch can safely be paralleled. Do not parallel lithium batteries from different manufacturers or different capacity (Ah) ratings -- the BMS systems may conflict. Some manufacturers (Battle Born, Renogy) explicitly support and document their parallel wiring configurations. Battery location: batteries must be in a vented compartment -- hydrogen gas is produced during charging (even lithium batteries, from the electrolyte). Most RVs have a battery compartment on the tongue (travel trailers) or in a basement bay (motorhomes) with a vent to outside. Do not install batteries in a sealed interior space.

Pro tip: After your battery bank is wired and charged, discharge it completely (run loads until the BMS cuts off or voltage drops to 11.5V for AGM), then charge it fully. This initial cycle calibrates the battery's capacity estimate and, for lithium batteries, allows the BMS to balance cells. A brand-new battery bank that has never been cycled often reads higher capacity than its rated spec on the first charge, then settles to true capacity after one or two cycles.

Set up monitoring and battery maintenance

A solar system without monitoring is a black box. You won't know how much capacity you have, whether the panels are producing, or when you need to adjust your power consumption. Monitoring makes the system actually useful. VictronConnect app: if you installed a Victron SmartSolar charge controller, download VictronConnect on your phone. Connect via Bluetooth within 10 feet of the controller. The main screen shows: battery voltage, battery current (charging or discharging), solar production watts, state of charge (requires a Victron battery shunt for SOC), and a history of daily energy produced. Set up battery voltage high/low alerts in the app. Battery shunt for accurate SOC: the charge controller alone can't tell you how much of your battery is left -- it only sees what goes in via solar. A battery shunt (Victron BMV-712 or SmartShunt) measures all current in and out of the battery and gives you an accurate state of charge percentage. It mounts on the battery negative terminal. This is a $100 addition to the system that makes a huge practical difference -- you'll know "I have 60% left" instead of "I think the battery is okay." Daily monitoring habits: check the VictronConnect or BMV shunt display once in the morning (what's my SOC after overnight?) and once in the early afternoon (how much has solar produced today?). If SOC is dropping day over day in sunny weather, either your consumption is higher than expected or there's a production problem. If SOC is holding or climbing, the system is working correctly. Annual maintenance for AGM: AGM batteries benefit from an equalization charge (a controlled overcharge at 15.5V) once or twice per year to desulfate the plates. The Victron charge controller supports equalization mode. Do not equalize LiFePO4 lithium batteries -- they do not require it and the voltage will trigger BMS cutoff. Roof inspection: inspect every Z-bracket base and Dicor application at the start of each camping season. Any cracking, lifting, or gaps in the Dicor need to be touched up with fresh sealant before water gets in. This is a 30-minute inspection that protects the roof integrity you worked hard to maintain during installation.

Pro tip: If you see the charge controller in "float" mode by early afternoon, your solar production has fully charged the batteries and you have surplus power. This is the signal that you can run energy-hungry loads during the day -- run the microwave, charge laptops, run the blender -- without drawing down the battery. Float mode means you're making more power than you're using. Use it.

Panels on, batteries charging, monitoring live

System sized correctly, roof sealed, wiring fused, charge controller configured, battery bank working. You know your SOC in real time.

From $299.99

Same-day available · Satisfaction guaranteed

In-person only

RV solar installation requires a tech at your rig for the roof work and battery wiring -- this can't be done remotely.

By the numbers

MPPT vs PWM gain20--30% more power

Lithium usable capacity80% DOD

Peak sun hours (typical US)4--5 hrs/day

ANL fuse locationwithin 18" of battery

Boondock as long as the sun shines.

A properly sized and installed RV solar system means you're not rationing power, not running the generator at 6am, and not hunting for hookups.

If the roof work, the wiring, or the battery bank feels like too much for one afternoon, a Geek can design and install the whole system at your rig.