Is My Commercial Solar Project Working? How to Tell

You can usually tell whether your commercial solar project is working without touching any equipment: compare your electric bills, check the monitoring portal and look at the inverter's status light. When something is wrong, the cause is most often an inverter or a communications problem, not the panels. Most problems can be fixed, and if you'd rather not deal with it, you can sell the project as-is.

Picture a building owner whose electric bill is higher than last summer's. Nobody has logged into the solar portal in years. When someone finally does, it shows a flat line. One owner put it to us this way: "Production dropped, is the site dead?" Maybe. Often it is something smaller.

As a project ages, problems like this get more common. Here are the safe checks, the usual causes, and your options for getting it running again.

Four Safe Checks Show Whether It's Working

Compare what the project produces now with what it produced in the same months of past years.

Each of these can be done from a desk or from a safe distance:

• ●Your electric bills and net metering credits. Net metering is the utility arrangement that credits you for solar power the building did not use. Line up this year's bills against the same months in earlier years. If the bill climbed and the credits shrank, and the building's own use did not change, the solar is likely producing less.
• ●The monitoring portal. This is the website or app that shows daily production. It may be run by the inverter maker or by a separate monitoring company (more on both below). A slow, steady decline is normal aging. A sudden drop, or a flat line at zero, is not.
• ●Inverter status lights or screens. The inverter is the box that turns the panels' direct current (DC) into the alternating current (AC) your building uses. Most show a status light or a short message. Look from a safe distance, take a photo, and do not open any doors or covers.
• ●Your state incentive payments. In states that pay solar owners through certificates, such as SRECs, you earn one for every 1,000 kilowatt-hours the project makes. If you or your broker see fewer certificates than in the same months last year, production probably fell.

Look, but Don't Touch

A solar project can carry dangerous voltage even when it seems to be off.

Depending on how your system is set up, the wires running from the panels to the inverters can carry electricity even when the inverters are dead or switched off. As long as light is hitting the panels, they are making power, and turning off a breaker or switch does not make those wires safe.

Never open an inverter, combiner box or electrical panel, never touch wiring, switches or connectors, and never walk an array or a roof without proper training and fall protection. If you see scorch marks, smell burning or hear buzzing, keep people away and call a licensed electrician or your service provider right away.

A Blank Portal Usually Means Lost Reporting, Not Lost Power

When the portal shows no data, the project has usually stopped reporting, not stopped producing.

Monitoring depends on an internet connection, often through a small gateway or data logger in an electrical room. A new router, a changed Wi-Fi password, a disconnected network cable or a canceled internet line can all cut the link while the panels keep working. Inverter makers point to the internet connection first: Fronius's support page for its Solar.web portal, for example, lists a faulty or interrupted internet connection as the reason a system shows as offline.

To tell the difference, check your electric bill. If it still shows solar credits, the project is likely working and only the reporting is broken. Fix it anyway: without data, you will miss the next real problem. Our post on spotting underperformance from inverter data explains what good monitoring can reveal.

The Usual Causes in Older Projects

Most often an inverter that has tripped or failed, lost communications, or a fault somewhere in the wiring.

• ●A tripped or failed inverter. Inverters wear out well before panels. The U.S. Department of Energy has noted that the typical inverter lasts about 10 years, while panels can last 20 to 30. Our post on commercial inverter failure and repowering covers this in depth.
• ●A utility outage or grid event. For the safety of line workers, inverters are designed to shut off when the grid goes down, and they normally restart on their own once power returns. If the project is still off after the grid is back, that is a service call.
• ●Blown fuses or a ground fault. A ground fault is electricity leaking to a place it should not go, often through damaged insulation. Inverters shut down a circuit, or the whole unit, to protect against it. Only a qualified technician should find and fix these.
• ●Damaged wiring or connectors. Years of sun, heat, wind and animals can crack insulation and loosen connectors on a roof.
• ●Shading, vegetation and dirt. A tree that has grown, a new rooftop unit, or a layer of grime or bird droppings can cut output on part of the array.
• ●Normal aging. Panels lose a little output every year. A review of nearly 2,000 field measurements by the National Renewable Energy Laboratory found a median decline of 0.5% per year. That does not explain a sudden drop. Our post on what causes commercial solar degradation goes further.

Getting Back Into Your Monitoring Portal

Find out which company runs your portal, then contact it with your serial numbers and proof that you own the project.

Many projects use the inverter maker's own portal: SolarEdge, Enphase, Fronius (Solar.web) and SMA (Sunny Portal) all run one. Many older commercial projects use a separate monitoring company instead, with names like AlsoEnergy (PowerTrack), Locus Energy, Draker or Fat Spaniel. If one of those names is on an old login page, an email or a box in your electrical room, that's your portal.

Several of those companies have changed hands. AlsoEnergy merged with Locus Energy and bought Draker in 2018, and moved Draker customers onto its PowerTrack platform. Fat Spaniel was bought by inverter maker Power-One in 2010. On older projects, the installer often set up the account and may hold the login, or may be out of business.

Before you call, gather the inverter serial numbers (printed on a label on the unit, which you can photograph from a safe distance), the site address, and documents showing ownership, such as a purchase agreement or deed. If ownership records are thin, our post on what to do when solar ownership is unclear can help.

Who Wants the Headache?

You can sell the project as-is and let the buyer deal with it, or hire someone to fix it.

Do Good Energy buys any project, working or not. We figure out what's wrong, work to repower it and own it for the long term, taking over the contracts and responsibilities that come with it. You don't chase down logins, hire technicians or wait on parts. Our instant solar estimate gives you a starting range in about 23 seconds from six quick questions, with no paperwork and no commitment.

If you'd rather keep it and fix it yourself, look for a commercial operations and maintenance (O&M) provider, ideally with NABCEP-certified staff and licensed electricians. Commercial projects are larger and more complex than home systems, and many residential installers do not service them. NABCEP, the main national certification body for solar professionals, offers a commissioning and maintenance specialist certification, and you can search its directory of certified professionals. Any electrical work must also be done under a licensed electrician as your state requires.

Ask for a diagnostic visit first, not a repair. A good diagnostic includes:

• ●A check of each inverter and its fault codes
• ●IV curve tracing, a test that measures how each string of panels performs electrically
• ●Thermal imaging for larger projects, which uses an infrared camera to find hot spots from failing panels or connections
• ●A written report that separates what failed, what is at risk, and what is optional

When the quote arrives, check that it names the exact failed parts, says whether replacement parts are still made, and lists what is excluded. Our post on how to judge a commercial solar repair quote walks through it line by line.

When Fixing Stops Making Sense

Most failures are in inverters and other parts that can be repaired or replaced, not in the panels. But the bills can keep coming.

Signs it's time to stop paying for repairs: inverter models that are no longer made, one repair after another, a roof that needs replacing under the array, or incentive payments that are ending. At that point the question shifts from how to fix it to whether you want to keep owning it.

See what your project is worth in about 23 seconds, or read our state-by-state solar guide for the rules where your project is.