Solar panel repair in Maryland should start with a diagnosis of the failed component. A production alert alone can’t tell you which part needs work. Ask the technician to document the fault, the evidence behind the recommendation and the checks planned after the repair. Electrical testing belongs to qualified professionals.1,2,3
One scope note before the detail. The main technical reference here is a December 2018 maintenance report from the National Laboratory of the Rockies (NLR, formerly the National Renewable Energy Laboratory). It was written for larger solar plants. Its testing logic carries over to a house, but its crews, equipment and costs don’t, so we leave its dollar figures out.1
What can fail on a rooftop system?
A fault can sit in the inverter, in a circuit of connected panels, in wiring and connectors, or in the monitoring equipment. The symptoms overlap. An app warning or a blank graph can’t prove that panels need replacing, so a technician starts from the layout and the operating record.1,4,5,2
A photovoltaic (PV) system includes the panels and the equipment that converts and delivers their electricity. Panels produce direct current (DC), and inverters convert it to alternating current (AC) for household use. Southern Maryland Electric Cooperative (SMECO) explains the difference on its solar safety page.6
The NLR report calls the inverter one of the most frequent causes of performance loss in PV systems (it cites a 2010 industry study for that point) and says different inverter types fail and get replaced in different ways.4 The Maryland Energy Administration (MEA) says a complete stop in daytime output can come from blown fuses, wiring problems, breakers or ground faults.7
| Suspected area | What a professional investigates | What to request before approving work |
|---|---|---|
| Inverter | Recorded events, operating conditions and the installed inverter arrangement | The identified fault and the evidence that places it at the inverter.4,7 |
| String (panels wired in a series circuit) | Electrical behavior of the affected circuit compared with its design | The circuit, the measurements and the conditions during testing.2 |
| Wiring or connectors | Physical damage, wear, loose connections, damaged insulation | The location and nature of the defect, with photos where access is safe for the professional.5 |
| Monitoring or communications | Data collection, communications, and whether the records reliably show production | What data is missing and what was checked independently.1,2 |
| Panel or module | Physical condition and electrical performance | The specific panel and the test findings behind a repair or replacement, including any safety concern.2,8 |
Stay on the ground. Equipment access and electrical testing are the technician’s job.
What does a good diagnostic visit look like?
A diagnostic visit ties the problem you reported to evidence about the equipment on your roof. The professional reviews records, checks for safe access and picks tests for the suspected fault. You should leave with a written finding that separates confirmed defects from open questions, and nothing replaced before that finding exists.1,9,10
It runs in five stages:
- History. You say when the problem began and mention any storm, roof work, equipment change or loss of monitoring. Hand over drawings, equipment records and earlier service findings if you have them.9
- Equipment. The technician ties each finding to a component or circuit. System design matters here, because different inverter arrangements react differently when a part fails.1,4
- Tests. Before each inspection or test, the technician says what it will show and what it can’t. Testing follows the equipment instructions and the professional’s own safety procedures.2,8
- Recommendation. You get the confirmed cause, the proposed work, the remaining uncertainty and any manufacturer involvement.9,11
- Return to service. The Department of Energy’s recovery guidance for PV systems ends with a full recommissioning and a return to performance monitoring. Your provider should be able to tell you how it will do the same.10
Some faults need a second visit, manufacturer support or better test conditions. Agree on what the first visit includes, because specialized tests and the repair itself may be separate jobs.
What can electrical tests and thermal images show?
The two methods answer different questions. Electrical testing measures how a circuit behaves, and thermal imaging shows where something runs hot. Neither settles every question, so have the technician name the test conditions, the suspected cause and whether a second method has to confirm the finding.2,8
| Method | What it can reveal | What it can miss |
|---|---|---|
| Manual electrical testing (open-circuit voltage, operating current, field current-voltage curve tracing) | Faults in the DC circuit that monitoring doesn’t catch.2 | Hot-spot defects that aren’t yet cutting a module’s output. For curve tracing, standard field units are limited to around 5 percent accuracy.2 |
| Aerial thermal imaging (drone or aircraft surveys, described for large arrays) | Hot spots, failed modules and failed strings, and their rough location.8 | The exact cause, unless the images go through a validated processing routine. Without one, NLR says the survey only points to symptoms and ground troubleshooting is still required.8 |
NLR’s report shows one module with compromised electrical insulation that kept producing power. Keep that in mind when a system “looks fine” on the monitoring app. Continued production isn’t proof that damaged equipment is safe.2
Take a made-up case. A thermal report flags a warm area on one panel and includes no electrical findings. What defect does the image support? Did the technician confirm it on the roof or only on a screen? What’s still untested? A warm spot is a lead, and it doesn’t justify replacing the panels around it.
Repair or replace: how do you weigh a recommendation?
The right answer follows the confirmed defect, the equipment design, manufacturer support, parts availability and the scope of work. If a provider recommends replacing several components, the evidence for the wider scope should come with the proposal, along with the limits of a narrower repair.2,11,12
For inverters, NLR names inverter size and type, repair support, parts availability and cost as decision factors, and flags compatibility problems with replacements, including physical dimensions and electrical configuration. In its large-plant setting, a manufacturer can take up to about one month to ship a warranty replacement string inverter. The same passage says swapping a string inverter is quicker than repairing a central one and can be done by an electrician.11,4
| If the finding is | Then ask | What could change the answer |
|---|---|---|
| One inverter has a confirmed fault | Can it be repaired or replaced without broader changes? | Parts availability, manufacturer support, whether the replacement fits the existing wiring.11 |
| A whole string is proposed for replacement | What shows that each change is necessary? | Test findings on every affected panel, in writing.2 |
| The defect may fall under a manufacturer warranty | Who decides the claim, and does the written coverage include labor? | Claim acceptance and exclusions.12 |
| The cause is still uncertain | What further test would settle it? | New evidence can change the scope.1,2 |
Here’s a second example. A technician confirms a damaged cable while panel performance stays acceptable. The sensible proposal fixes the cable and checks the result, and broader replacement would need its own explanation. It shows how to read a recommendation, not what’s wrong with your system. Our guide to how solar panel warranties work covers the claim side.
Which licenses and permits apply to repair work?
Match the license to the work. Maryland’s Home Improvement Commission says a home improvement license doesn’t authorize electrical work. For a repair that changes equipment, the report should be clear enough for the permit office and the utility to say whether they need to approve it.13,14
As of October 2026, the Maryland State Board of Electricians says all electrical work in the state must be done by a licensed master, journeyperson or apprentice electrician, and that unlicensed electrical work is illegal. The board tells the public to verify an electrician’s license in its search tool.3 The Home Improvement Commission (MHIC) says solar panel systems must be mounted by a licensed home improvement contractor.13
The two pages describe electrician licensing differently. MHIC’s page says the person who connects panels to the electric box or the grid needs an electrician’s license “issued by the local jurisdiction.” The State Board’s page and Montgomery County’s permitting page treat electrician licenses as state-issued.3,13,14 The State Board’s search tool is the lookup to use. Neither page speaks to any particular provider’s credentials. Our guide on how to check a solar contractor’s license in Maryland walks through the lookups.
Two local notes:
- Montgomery County. The Department of Permitting Services (DPS) electrical page lists permits with and without a building permit, a residential PV system installation certification and permit guidelines for solar systems. It also says all electrical licenses are now solely issued by the State of Maryland. Ask DPS about your exact repair, since some may need a permit and some may not.14
- SMECO territory. The cooperative’s safety page describes the difference between solar equipment and its disconnects. Have your provider name any utility approval the equipment change needs, because a repair recommendation isn’t permission to alter the grid connection.6
Permit rules vary by property and by the work, so treat this section as orientation rather than a county checklist.
When should you stop reading and get safety help?
Smoke, fire, sparking, damaged wiring or water in electrical equipment call for professional help right away. SMECO’s guidance for the public is to call 911 and tell the dispatcher the property has a solar PV system. Its list of injury-prevention rules includes staying at least 10 feet from a solar installation and never contacting a damaged system.6
An off display doesn’t mean the equipment is dead. SMECO also notes that panels stay energized as long as the sun is shining, even after a disconnect is opened.6
MEA’s January 2018 consumer guide adds that voltages inside an inverter can reach 600 volts DC, which is why it calls troubleshooting a job for a qualified solar professional.7 Keep your own preparation to records and screenshots. Don’t open an inverter, remove covers, handle connectors, reset protection repeatedly or try roof work.
Who can assess the fault?
Soleil Energy’s monitoring and maintenance page lists fault diagnosis and repair and says it services systems it didn’t install. Ask for an assessment of the fault, then confirm whether your equipment and the work you need fall within what Soleil Energy offers. Find out what the assessment includes before assuming a particular repair is part of it.15
Have your equipment records, monitoring screenshots and earlier findings ready. If the provider needs monitoring access, use an authorized account-sharing method and keep passwords out of the inquiry. Our guides on who services your solar panels and why a solar system stops producing help you prepare.
Manufacturer-controlled access, unavailable parts and unsafe access can all slow an investigation. Roof leaks need their own assessment, and panel replacement needs a confirmed scope.
To discuss your system’s symptoms and the assessment scope, request a system assessment or call (301) 953-4140.
This guide is general information, not legal, tax, or financial advice.
Sources (15)
-
National Laboratory of the Rockies (formerly National Renewable Energy Laboratory) and partners, Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems, third edition, published December 2018, sections on root-cause analysis and monitoring, https://docs.nlr.gov/docs/fy19osti/73822.pdf; read October 25, 2026. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14
-
Same source as 1, section 9.1.1 (manual electrical testing; the 5 percent accuracy limit is stated for field current-voltage curve tracing). ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13
-
Maryland Department of Labor, State Board of Electricians, Notice to the Public, https://labor.maryland.gov/license/elec/; undated, current page read October 25, 2026. ↩ ↩2 ↩3
-
Same source as 1, section 5.2 (inverter types, failure frequency, replacement timing). ↩ ↩2 ↩3 ↩4 ↩5
-
Same source as 1, electrical system and wire management. ↩ ↩2
-
Southern Maryland Electric Cooperative, Solar Panels (safety guidance), https://www.smeco.coop/safety/solar-panels/; undated, current page read October 25, 2026. SMECO serves southern Maryland; the safety guidance applies to solar equipment generally. ↩ ↩2 ↩3 ↩4
-
Maryland Energy Administration (with Clean Energy States Alliance), A Maryland Consumer’s Guide to Solar, published January 2018, pages 39-40, https://energy.maryland.gov/residential/Documents/A%20Maryland%20Consumers%20Guide%20to%20Solar%20LR72dpi.pdf; read October 25, 2026. Used for safety and troubleshooting principles only, not prices, tax or program rules. ↩ ↩2 ↩3
-
Same source as 1, section 9.1.2 (aerial thermal imaging and its limitations). ↩ ↩2 ↩3 ↩4 ↩5
-
Same source as 1, document management and record keeping. ↩ ↩2 ↩3
-
U.S. Department of Energy, Federal Energy Management Program, Life Cycle of Photovoltaic Systems: Operate and Maintain an Existing Photovoltaic System (post-damage recovery section), https://www.energy.gov/cmei/femp/life-cycle-photovoltaic-systems-operate-and-maintain-existing-photovoltaic-system; undated, current page read October 25, 2026. Facility guidance used for recovery principles only. ↩ ↩2
-
Same source as 1, section 5.2 (inverter repair and replacement decision factors, string-inverter replacement timing). ↩ ↩2 ↩3 ↩4
-
Same source as 1, warranties and coverage limitations. Check the actual equipment’s written terms. ↩ ↩2
-
Maryland Department of Labor, Home Improvement Commission, Understanding Maryland’s Licensing Requirements for Green Technology, https://labor.maryland.gov/license/mhic/mhicgreen.shtml; undated, current page read October 25, 2026. ↩ ↩2 ↩3
-
Montgomery County Department of Permitting Services, Electrical & Mechanical Codes, Licenses and Permits, https://www.montgomerycountymd.gov/department-permitting-services/codes/electrical-mechanical-codes-licenses-permits; undated, current page read October 25, 2026. Applies only where DPS has jurisdiction. ↩ ↩2 ↩3
-
Soleil Energy, Monitoring & O&M, https://soleilenergycorp.com/renewable-energy/monitoring-and-om/; undated, current page read October 25, 2026. ↩
