Rooftop Solar Array Installation and Repair for RVs
Written by RV Systems Lead, RV Systems and Electrical Lead, OCRV Center. Reviewed by Structural Repair Lead
In shortAn array that underperforms is usually shaded, wired to the wrong controller, or losing volts in the run. Roof solar work runs $1,500 to $12,000+.
What is involved in RV rooftop solar array installation and repair?
Rooftop solar work covers panel mounting, roof penetrations, cable routing, controller selection and integration with the house bank. Rancho Santa Margarita owners bring arrays to our Yorba Linda shop because a solar project is a roofing job as much as an electrical one, and a leaking bracket costs more than the panels.
- One shaded panel can flatten an entire series string
- MPPT harvests meaningfully more than PWM on a high voltage array
- Every roof penetration is a future leak unless it is bedded properly
- Controller placement matters because heat forces it to derate
- Price range
- $1,500 to $12,000+8 to 40 labor hours at $260 per hour
- Labor rate
- $260 per hourMechanical and electrical department
- Typical turnaround
- 3 to 10 shop daysSealant cure time is scheduled, not rushed
- Written estimate
- $150Credited in full against an authorized repair
- Controllers fitted
- Victron SmartSolar, Renogy Rover, MorningstarSized to array voltage and bank chemistry
Last verified
Solar arrives at our shop in two forms. Either an owner wants one and has been quoted wildly different numbers by three people, or an owner already has one and it makes roughly half the power somebody promised. The second case is far more common, and the reasons behind it are consistent enough to be predictable.
There is also a truth about this work that panel brochures never mention. Putting solar on a roof means making holes in a membrane that was doing an excellent job of keeping water out. How those holes are made and sealed determines whether the project is a success or the opening chapter of a delamination repair two years later.
Why an array makes half the power on the sticker
Panel ratings are laboratory numbers taken at a specific irradiance and cell temperature, and a roof in Orange County in August is not that laboratory. Some loss is unavoidable and every honest installer builds it into the expectation. What we are looking for is the gap beyond that, the systems where an owner was promised a number and receives well under half of it every single day regardless of conditions.
Those cases come down to four things: shading, controller type, wiring losses, and a component that has quietly failed without announcing itself. Each leaves a distinct signature in how production behaves through the day, which is why we log output across a full daylight cycle before opening anything. Time of day patterns tell us more than any single meter reading.
- Falls off at a specific hour: shading on a series string
- Uniformly low all day, perfect conditions: controller type or wiring loss
- One string weak, others normal: connector corrosion or a failed diode
- Good output that never reaches the bank: controller configuration or drop in the run
MPPT and PWM controllers are not interchangeable
A pulse width modulation controller connects the array to the battery and pulls the panels down to whatever the battery happens to be sitting at. If the panels want to operate near eighteen volts and the bank is at thirteen, the difference is not converted into anything useful. It is simply not harvested. On a small twelve volt panel matched to a twelve volt bank that loss is tolerable.
A maximum power point tracking controller converts instead of clipping. It lets the array sit at its own optimal voltage and steps that down to what the bank needs, keeping the power rather than discarding it. The gain is real and it grows as array voltage rises above battery voltage, which is exactly why higher voltage residential style panels are worth using on an RV roof at all.
Note
Array voltage rises as temperature drops. A controller sized against a warm afternoon reading can be pushed past its input limit on a cold desert morning, so we size against the coldest condition the coach will realistically see.
Series, parallel and the shadow of a rooftop air conditioner
Wiring panels in series adds their voltages, which suits an MPPT controller and keeps cable losses low over a long run. The cost of that arrangement is that current has to pass through every panel in the string. Shade one and the rest are limited to what the shaded one can pass, which is why a single vent shadow can knock most of a string out of production.
Parallel wiring trades that away. Each branch works independently, so a shaded panel only removes its own share, but the current adds up and the cable has to be sized accordingly. RV roofs are cluttered with obstructions that move their shadows across the day, so most of the layouts we design end up as a hybrid, with series pairs arranged so that no shadow crosses both members of the same pair.
- Map shadow positions across a full day before choosing a topology
- Group panels so a single obstruction cannot shade both halves of a series pair
- Size conductors to the current a parallel arrangement actually produces
- Split large arrays across multiple controllers where the roof is badly obstructed
Roof penetrations are the part that goes wrong
Every bracket is a hole through a waterproof layer, and the way that hole is treated decides the outcome of the whole project. The failure we repair most often is topical: somebody set the foot down dry, drove screws, then went around the outside with sealant. Water does not enter at the screw head. It travels under the foot along the membrane and finds the fastener from beneath, where the sealant never was.
Done correctly the bracket is bedded in butyl so the underside is sealed before anything is fastened, the fastener lands in material capable of holding it, and self leveling sealant caps the assembly afterward as a second line rather than the only one. Cable entry gets the same treatment through a gland with a drip loop, not a drilled hole full of adhesive.
Before you proceed
If a ceiling stain has already appeared near a bracket, the scope is no longer a solar job. Decking and framing get inspected before anything is refastened, because a screw into wet lauan holds nothing.
How a new array goes on at our Yorba Linda facility
The order of operations is deliberate. Survey and shade mapping come first, structure verification second, and only then does anything get drilled. Cable routing is planned to keep the run short and away from heat, and the controller location is chosen for airflow because a device that derates in a hot bay will never deliver its rating no matter how good the array above it is.
Commissioning is where a lot of installations quietly fail. A controller left on factory defaults will charge to whatever profile the manufacturer guessed at, which is rarely correct for the bank actually in the coach. We set absorption voltage, absorption time and float to the installed chemistry, confirm the same settings across every other charge source, and then measure production in real sun.
Where the hours go on a solar project
Solar bills through the mechanical and electrical department at $260 per hour, and the eight to forty hour spread on this page mostly reflects roof work rather than electrical work. Panels and a controller are quick. Verifying structure at six mounting points, adding backing from inside a ceiling, routing cable through a wall cavity and letting sealant cure properly are what consume days.
Components carry standard parts markup with tax on parts and materials only. A written repair estimate is $150 and credits back in full against an authorized repair. Larger installs pass the deposit threshold at authorization and, on the biggest projects, a further deposit applies when parts arrive. Both are stated up front so nothing about the money is a surprise.
On cost
We quote roof preparation separately from the solar hardware. An owner is entitled to see how much of the number is panels and how much is making a tired roof fit to carry them.
Aftermarket arrays and what a carrier needs to see
A rooftop array is exposed to exactly the events policies care about: hail, wind, falling branches and debris off the 241. It is also an aftermarket addition that a base policy may not contemplate, so the value only exists on paper if somebody wrote it down. Receipts, panel model numbers, controller serial and installed wattage belong in a file the day the work is finished.
After an event, sequence decides everything. Photographs taken with the panels still in place, before anything is unbolted, are worth more than any description written afterward. We document arrays at intake as a matter of routine and keep the record with the job so a supplement has something to stand on.
What is included
- Roof survey and layout planning
- Panels are laid out around vents, fans, air conditioners and antennas with the afternoon shadow line considered before a single hole is drilled.
- Structural check of the roof at each mounting point
- We confirm what is under the membrane at every bracket location, because fastening into unsupported lauan is a repair waiting to happen.
- Sealed penetrations and cable entry
- Brackets are bedded in butyl and capped with self leveling sealant, and cable enters through a proper gland rather than a drilled hole.
- Controller sizing, mounting and configuration
- The controller is matched to array voltage and bank chemistry, mounted where it can shed heat, and configured rather than left on defaults.
- Protected wiring from array to controller to bank
- Conductor is sized for the run length, and fusing is fitted between controller and battery to the controller rating.
- Production verification against expected outputwhere applicable
- The finished array is measured in real conditions and compared with what the panels should deliver.
How the work runs
Survey the roof and map the shade
1 to 2 hours
We photograph the roof, measure clear areas around every existing penetration, and work out where shadows fall at different hours. This determines both panel placement and whether strings should be wired in series or split into parallel branches.
Verify structure and plan penetrations
1 to 3 hours
Every intended bracket point is checked for what sits beneath the membrane. Where backing is thin or soft we add it from inside rather than trusting a screw in decking that is already tired.
Mount, bed and seal
3 to 12 hours
Brackets go down on butyl, fasteners are set to the right depth, and the whole assembly is capped with self leveling sealant. Cable enters through a gland with a drip loop. This step is scheduled with cure time rather than squeezed.
Run conductors and commission the controller
2 to 14 hours
Cable is sized to the run and routed away from heat and chafe. The controller is mounted where air can move around it, then configured for the installed chemistry with absorption and float voltages set deliberately.
Measure real output and water test
1 to 9 hours
Production is recorded under real sun and compared with what the array should deliver, and the roof is water tested at every new penetration before the coach leaves. Both results go in the file.
What this costs
$1,500 to $12,000+
8 to 40 labor hours at $260 per hour, mechanical and electrical.
- Parts at $100 or less carry 100 percent markup. Parts over $100 carry 35 percent. Special order parts require a full non refundable deposit at order.
- Sales tax of 7.75 percent applies to parts and materials. Labor is not taxed.
- A 50 percent deposit is taken at authorization on any job over $2,000, with an additional 25 percent when parts arrive on any job over $10,000. Final balance is due at pickup.
- Repairing an existing array with a controller swap and connector work sits at the bottom of this range.
- A large multi panel install with new trunk cabling, structural backing and a high capacity controller sits at the top.
- Panels, controllers, brackets and sealant are billed as parts with standard markup.
How estimating is billed
- Written repair estimate: $150, credited in full against an authorized repair.
- In depth diagnostic, scan and programming: $285 per hour, one hour minimum, credited in full against an authorized repair.
- In shop pre purchase inspection: $400 to $1,200 depending on unit size and systems count.
- Insurance walk ins are accepted during posted hours. All inspection and estimating work is performed in shop at the Yorba Linda facility.
What you will notice first
- The controller reads zero amps at noon on a cloudless day
- The array produces strong current in the morning and collapses after two in the afternoon
- Output is roughly half of what the panel labels add up to, every day, in every condition
- A brown stain has appeared on the ceiling panel near one mounting foot
- The controller display resets or goes blank when the bay gets hot
- A flexible panel has bubbled or gone cloudy across part of its surface
- The bank charges from solar but the monitor never shows the array at full rating
- One panel is warm to the touch while its neighbors on the same string are cool
How this fails, and what we do about it
| Failure mode | How we diagnose it | The fix |
|---|---|---|
| String collapse from partial shading | Production tracks the sun beautifully until a specific hour, then falls off a cliff. Walking the roof at that hour shows the shadow of an air conditioner shroud or an antenna crossing one panel. In a series string that single shaded panel limits everything behind it. | Rewire the affected panels into parallel branches, or relocate the panel clear of the obstruction. On larger arrays a controller per string removes the interaction entirely. |
| Controller mismatch on a high voltage array | Panel labels total far more than the controller ever reports, consistently and in perfect conditions. A PWM device pulls the array down to battery voltage, so the difference between panel operating voltage and battery voltage is simply lost. | Replace with a correctly sized MPPT controller and confirm the array voltage stays inside the controller input rating at the coldest temperature the coach will see. |
| Corroded MC4 connector | One string reads well below its neighbors, and thermal imaging on a sunny day shows a warm spot at a connector rather than at a panel. Opening the connector reveals green contacts and often a crimp that was never made properly. | Cut back to clean conductor, fit new connectors with a proper MC4 crimp die, and seat them until they click. Hand tightened connectors are the most common source of this fault. |
| Leak at a mounting foot | A ceiling stain or soft spot appears directly inboard of a bracket. Water testing the roof with the panel in place traces the path to the fastener, usually because sealant was applied over a screw rather than under the foot. | Remove the foot, clean the membrane back to sound material, bed the bracket in butyl, refasten and cap with self leveling sealant. Interior damage is scoped separately. |
Why it happened
- Panels mounted flat behind a rooftop air conditioner or a vent stack, where afternoon shade lands on cells wired into a series string and collapses the whole string
- A PWM controller installed on an array whose panels were designed for higher voltage operation, which throws away a substantial share of available power as heat
- Long undersized cable between the roof and the controller, where voltage drop under current makes the controller believe the array is weaker than it is
- Water ingress into MC4 connectors that were mated on the roof without a proper crimp, corroding the contact and adding resistance in a wet season
- Flexible laminate panels adhered directly to a membrane roof with no air gap, which cooks them from below and shortens their life dramatically
- A junction box bypass diode that failed open after a shading cycle, which quietly removes a whole panel from production without any visible symptom
Parts and brands we work with
- Victron SmartSolar MPPT controllers with Bluetooth configuration and logging
- Renogy Rover and Morningstar controllers on smaller and mid sized arrays
- Rigid aluminum framed monocrystalline panels with mechanically fastened feet
- Dicor self leveling lap sealant over butyl bedded mounting brackets
- Weatherproof cable entry glands rather than a hole with sealant over it
- Blue Sea fusing between the controller and the house bank, sized to the controller
What not to try yourself
- Fastening panel brackets into a roof without confirming what is underneath. Screws into thin decking pull through with the first crosswind on the 91 and take a section of membrane with them.
- Sealing a mounting foot by squirting sealant over the screw heads afterward. Water tracks under the foot, not through the fastener, and topical sealant hides the leak while it develops.
- Adhering flexible laminate panels flat to a membrane roof. With no air gap they run extremely hot, lose output permanently and can soften the surface they are stuck to.
- Connecting an array to a bank without protection between the controller and the battery. That conductor can carry fault current from the bank side, which is the direction people forget.
Which vehicles we do this on
Vehicles we perform Solar and Controllers on
Class BClass B camper van repair covers the van unibody, the bonded fiberglass high top or pop top, and the RV systems the coach builder installedCamper Van ConversionCamper van conversion repair covers aftermarket build outs in bare cargo vans: Sprinter, Transit and ProMaster shells finished by a shop or an ownerExpedition RVExpedition RV repair covers composite panel habitats, the torsion free subframe that isolates them from a flexing 4x4 truck frame, and bonded window and hatch framesStandardStandard fifth wheel repair concentrates on the pin box and upper deck welds, the floor at the step up transition, the front cap above the pin and the roof front radius seamTravel TrailerTravel trailer repair covers A frame tongue welds, the front cap that takes road debris, the roof front radius seam, sidewall delamination starting at a window corner, and equalizer and axle wearOverland CamperOverland camper repair covers the spring or pivot mounting system, dust sealing at doors and hatches, composite corner cracking and interior fastener fatigueI do the shade walk before I quote anything. Twice a day, roof level, camera in hand, watching where the air conditioner shroud puts its shadow. Owners get frustrated because it feels like I am stalling on a simple install, and then I show them the photo at three in the afternoon with a shadow lying across two panels they wanted wired in series. Ten minutes on the roof saves an argument about production numbers six months later. The other thing I will not rush is sealant cure. That is the roof, not an accessory.
Appendix: questions and answers
- Why does my solar array produce far less than the panel ratings suggest?
- Rated wattage is a laboratory figure at a controlled temperature and irradiance, so some shortfall is normal. Losses well beyond that point at shading, a controller that clips rather than converts, voltage drop in a long run, or a failed diode. Output logged across a full day identifies which.
- Is an MPPT controller worth the extra cost over PWM?
- On any array whose operating voltage sits well above battery voltage, yes. A PWM unit pulls the panels down to the bank and discards the difference. MPPT converts it instead. The gap widens with higher voltage panels, which are the ones worth putting on a roof anyway.
- Can shade on one panel really affect the whole array?
- In a series string, yes. Current has to pass through every panel, so the shaded one limits the rest. Parallel branches avoid the interaction but need heavier cable. We map shadows across a day and design the topology so no single obstruction can flatten a string.
- Will mounting solar panels make my roof leak?
- Only if the penetrations are done badly. Water travels under a bracket along the membrane and reaches the fastener from below, so sealing the outside afterward does nothing. Brackets bedded in butyl before fastening, then capped with self leveling sealant, hold up for the life of the roof.
- Are flexible solar panels a good choice for an RV roof?
- They are attractive for curved surfaces and low profile builds, but glued flat to a membrane with no air gap they run extremely hot, lose output permanently within a few seasons and can soften the roof beneath them. Where a rigid framed panel fits, it lasts considerably longer.
- Can a rooftop array run my air conditioning?
- Not from the panels directly. Roof air draws far more than any RV sized array produces in real time, so what makes it possible is a large bank plus a capable inverter, with solar acting as the refill between cycles. We size the array to daily consumption, not to peak load.
Open a file on this repair
Tell us the vehicle, what happened and whether a claim is open. We will tell you what the scope looks like and what it takes to get you back on the road.
Or call (949) 799-3387