If you’ve ever stood under a blazing sun watching your solar panels go from cranking out kilowatts to barely pushing out a handful, you know how frustrating that drop in power can be. As a solar panel supplier I’ve seen it all—from homeowners panicking over a single dimmed panel to small business owners wondering if their entire array is shot. The good news? Most of the common solar panel issues that derail performance are fixable without calling in a $200-an-hour technician. I’ve put together this troubleshooting guide using real experiences from our customers, field calls my team has handled, and the technical specs we work with every day to help you diagnose and fix problems fast. Solar Panels
Let’s start with the most common issue I see, and it’s not something wrong with the panels themselves—dirt, debris, and buildup. It sounds silly, but a thin layer of dust, bird droppings, pine needles, or even pollen can cut a panel’s output by 10% to 25% if left alone, especially in dry, dusty climates or areas near construction or forests. Last year we had a customer in Phoenix who reported a 30% drop in production for two months before he reached out. When our team showed up, his panels were caked with so much dust you could barely make out the solar cells. We didn’t replace a single panel—just gave them a gentle rinse with deionized water and a soft brush, and his power was back up within hours. The key here is how you clean them, though: never use a power washer. The high pressure can crack the thin glass covering on the cells, or force water under the frame and damage the wiring connections. If you’re cleaning them yourself, aim for an overcast day to avoid water spots drying in the sun, and use a mild soap (dish soap works fine) mixed with deionized or rain water, not hard tap water that leaves mineral streaks. For taller arrays, invest in a soft-bristle brush with a long extension pole, or hire a local cleaning service that specializes in solar panels—we usually recommend that for customers who don’t want to climb on their roof.
Next up: shading, which is another performance killer, and it’s often temporary or fixable with small tweaks. Shading doesn’t have to be a giant oak tree over your entire array to matter—even a small patch of shade from a chimney, a vent pipe, or a leaning tree branch can bring down the whole system’s output, because solar panels are wired in series. That means every panel’s current has to pass through the next one, so if even one panel is shaded, it acts like a clog in a pipe, reducing the flow for all the others. I had a customer in Colorado last spring who noticed his weekend power usage was way lower than his weekday numbers. Turned out, a pine tree that had grown over the winter was casting a 2-foot shadow on the corner panel of his 10-panel array every Saturday and Sunday morning. All we did was trim the overhanging branches back 3 feet, and his weekend power jumped back up by 18%. If you have permanent shading that you can’t fix (like a neighboring building that will always block part of your array), ask your installer about adding microinverters to your system. Unlike traditional inverters that work for the whole array, microinverters are attached to each individual panel, so a little shade on one won’t drag down the rest.
Moving on to electrical issues, which are the trickiest to spot because they’re not always visible. The most common electrical problem is loose or corroded connections. Over time, weather—extreme heat, cold, rain, and wind—can loosen the wiring connectors that link your panels together or connect them to the inverter. Corrosion happens when moisture gets into the connectors, especially if they weren’t sealed properly during installation. Signs of this are random drops in power, flickering readings on your inverter display, or even error codes popping up. Last summer we had a customer in Florida whose inverter kept throwing a “low voltage” error, and he’d reset it every week to get power back. Our technician checked all the connectors and found that one of the main wire junctions had been exposed during a heavy rain, corroding the metal terminals inside. We cleaned the corrosion, resealed the connection with a waterproof sealant, and he never had the error again. Important note here: never work on electrical connections yourself if you’re not licensed. Solar systems hold a charge even when they’re not producing power, so turning off the breaker isn’t always enough. If you see error codes on your inverter, take a photo of it, write down the code, and either call your installer or your solar supplier for guidance.
Another electrical culprit: faulty inverters. The inverter is the heart of your solar system, turning the direct current (DC) that panels produce into alternating current (AC) that your home or business uses. Inverters don’t last forever—most have a lifespan of 10 to 15 years, compared to 25 to 30 years for good quality solar panels—and they can develop issues even before that. Signs of a bad inverter include the unit running hot to the touch, making unusual noises (like clicking or humming that’s louder than normal), or the display being blank even when the sun is out. A few years ago we had a customer with a 8-year-old system whose inverter died completely. We tested the panels first to make sure they were working, then confirmed the inverter was the problem, and helped them source a replacement that matched their array’s specs. If your inverter is under warranty, most reputable suppliers will cover the cost of parts or labor, so make sure you keep track of your original installation paperwork when you get your system set up.
Now, what if you’ve checked all those things and your panels still aren’t working? It might be a damaged cell or a faulty panel, but there’s a way to test that without pulling every panel off your roof. You can do a simple voltage test with a multimeter, but again, be careful—this is DC power, so make sure the multimeter is set to the correct DC voltage range for your system (check your panel’s manual for the number). First, turn off the main disconnect for your solar system, then remove the connector from the front of the panel. Touch the red multimeter probe to the positive terminal of the panel and the black probe to the negative terminal. A working panel will produce a voltage close to its rated maximum voltage (most residential panels are between 30 and 40 volts). If the reading is 20% or more lower than that, the panel is likely damaged. Common damage that causes this is physical cracks in the solar cells, which can happen during installation, from hail, or even from falling debris. We had a customer in Texas a couple years back who had a hailstorm that cracked three of his panels—we replaced them under his warranty and his system’s power was back to normal. If you have cracked panels, don’t wait to replace them—moisture can get into the crack over time and cause more serious electrical damage.
Wait, let’s also talk about something that’s not a problem with the panels themselves, but with how you use your energy. A lot of new solar owners get frustrated when their system doesn’t cover all their electric bill, but that’s normal if you have a lot of high-energy appliances running during the day. If you’re running your electric oven, dryer, or water heater in the morning or evening when the sun isn’t shining, your panels aren’t producing enough power to cover that usage. I had a customer in California last year who thought his panels were broken because his bill was still $80 a month. We looked at his energy usage data and found he was running his dishwasher, washing machine, and water heater all between 6 and 8 PM, right when the sun was down. We suggested he shift those tasks to the afternoon, when his panels are producing the most power, and his bill dropped to $15 a month. If you track your production and usage data (most modern systems have an app that does this), you can easily spot if the issue is your energy habits, not your panels.
One final common issue that’s easy to overlook: tree growth over time. A lot of people plant small trees near their roof when they install solar, and years later those trees are tall enough to block their panels. I can’t tell you how many times we’ve gotten a call from a customer saying their panels “stopped working” and it turns out a tree they planted 5 years ago is now casting shade over half their array. If you have trees near your solar system, plan for regular trimming every 3 to 5 years to keep branches at least 3 feet away from the panels.
Troubleshooting solar panels doesn’t have to be complicated, but safety always comes first. Never climb on a roof if you’re uncomfortable, never work on electrical connections without the right training, and always turn off your system’s main disconnect before working on panels. If you’ve tried all these steps and your system is still underperforming, our team is here to help. Whether you need a quick diagnostic check, replacement parts, or a full assessment of your array, we have the experience and the parts to get your solar system running at peak performance.
We work with residential homeowners, small businesses, and agricultural operations, so no project is too big or too small. If you’re dealing with underperforming panels, suspecting damage, or just want to make sure your system is running as efficiently as possible, reach out to our team to connect for a consultation and quote.
LiFePO4 Battery References
- Solar Energy Industries Association (SEIA). 2023. "Solar Panel Maintenance and Troubleshooting Guide."
- International Electrotechnical Commission (IEC). 2021. "Photovoltaic System Safety and Performance Standards."
- National Renewable Energy Laboratory (NREL). 2022. "Shading Impacts on Photovoltaic Array Performance."
- North American Board of Certified Energy Practitioners (NABCEP). 2020. "Residential Solar System Troubleshooting Best Practices."
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