Why Only Half Your Solar Panels Are Working (And How to Tell)
- ifeoluwa Daniel
- 5 days ago
- 5 min read
Your system looks fine. The app shows green. But you could be losing 15–20% of your production right now — and never know it.
Here's something we see constantly at IntegrateSun: a homeowner has had solar for a year or two, checks their app occasionally, sees a number that looks reasonable, and assumes everything is working. Then they come to us for a second opinion — and we find that half their system has been quietly underperforming for months.
No error codes. No alerts. Just lost energy and lost money.
The frustrating part? Most of these problems are easy to spot once you know what to look for. Below are the four most common causes, along with how to check each one right now using your monitoring app.
1. Inverter Clipping: The Silent Performance Cap
This is the most common issue we find — and the one that frustrates us the most.
Inverter clipping happens when your panels can produce more power than your inverter can handle. For example, an installer pairs 420-watt panels with an inverter that maxes out at 380 watts. On a sunny afternoon when those panels are producing at full capacity, the inverter simply caps the output. It can't convert the extra power, so it's thrown away.
You paid for 420 watts. You're getting 380. Every single sunny day.
How to spot it: Open your Tesla app and look at your solar production graph on a clear day. A healthy system shows a smooth, rounded bell curve that peaks around midday. If yours hits a flat ceiling — a plateau that holds steady for a couple hours instead of curving — that flat line is clipping. Your panels want to produce more; the inverter won't let them.
The tricky part: your app won't flag this as an error. Everything shows green. You'll only catch it by looking at the shape of the curve.
2. Dead Microinverter or String Failure
If you have microinverters, each panel has its own small inverter underneath it. They're reliable, but they do fail. When one dies, that panel stops producing entirely — no warning, no alarm. Your total output drops 5–8%, which is easy to miss unless you're paying close attention.
String inverter systems have a different risk. Panels are wired together in groups (strings), and if one panel in a string has a bad connection or a failed optimizer, it can drag down every other panel in that group. One problem panel can take out six or eight.
How to spot it: Compare your daily production to the same month last year. If you're down 15–20% and nothing else has changed — same weather patterns, no new tree growth or shading — something is likely offline.
If you have access to panel-level or string-level monitoring (through SolarEdge or Enphase), look for:
One string producing significantly less than the others
A single panel reading zero while its neighbors are normal
A sudden drop-off on a specific date that never recovers
Any of those patterns points to a hardware failure, not a seasonal dip.
3. Critter Damage: The Problem Nobody Warns You About
This one surprises people, but it's more common than you'd think. Squirrels, birds, and raccoons love nesting under solar panels. It's warm, sheltered, and elevated — basically prime real estate for wildlife.
The problem: they chew through wiring. One damaged wire can take an entire string offline. Birds build nests that block airflow, causing panels to overheat and underperform. And none of this triggers an alert in your app.
How to spot it: This one's hard to catch from monitoring alone. The symptoms look identical to a string failure — production drops with no error code. If you've ruled out the first two causes, it's worth a physical inspection. Watch for:
Droppings on the driveway or ground directly below the array
Chew marks on any visible conduit or wiring
Nesting material poking out from under panel edges
If you see any of these, call a professional before the damage spreads to additional wiring.
One quick recommendation: If you don't already have critter guards installed, get them. They're inexpensive, they last the life of the system, and they prevent this entire category of problems.
4. Monitoring App Misread (Your Panels Might Be Fine)
This is the opposite problem — and it's worth checking before you panic.
Sometimes the Tesla Gateway loses its internet connection, and the app shows a gap in data or a period of zero production. The homeowner sees that and assumes something is broken. But in reality, the panels were generating normally the entire time. The monitoring just wasn't recording.
How to spot it: If your app shows zero production for a stretch of time but your electric bill doesn't spike, the app likely lost its connection. A few other telltale signs:
Production data cuts off at the same time every day (e.g., always drops to zero at 2 PM) — that's a connectivity pattern, not a panel failure
Gaps appear randomly but your bill stays normal month to month
The Gateway shows a "weak signal" notification
Before you call anyone: Reboot your Gateway (and your router), then check again after 24 hours. If the data comes back clean, you're good. The system was working — the reporting wasn't.
The 15% Rule: When It's Time to Call a Pro
Here's a simple rule of thumb: if your production is consistently down 15% or more from where it should be — and you've confirmed it's not a monitoring glitch — get a professional to take a look.
Don't sit on it. Every day your system underperforms is money lost. And in 2026, with the federal tax credit no longer available for new residential installs, every kilowatt-hour matters more. You paid full price for those panels. They should be working at full capacity.
Not sure if what you're seeing is normal? That's exactly the kind of thing we help with. We can review your monitoring data remotely — it takes about 10 minutes to spot most issues.
Quick Recap
Four reasons your solar panels might be underperforming right now:
Inverter clipping — your inverter can't keep up with your panels. Look for a flat-topped production curve.
Microinverter or string failure — a component died silently. Compare production year-over-year.
Critter damage — wildlife chewing wires under your panels. Inspect physically if other causes are ruled out.
Monitoring misread — the app lost connection, not the panels. Reboot and check your electric bill.
Check your app today. If something looks off, don't ignore it.
