Solar panels not producing enough can feel like money leaking off the roof. When solar panels are not producing enough, the cause is usually one of a short list of suspects, and most of them have fixes you can handle yourself. Before you spend anything, start with the free checks: is the monitoring app actually reporting correctly, and is anything new shading the roof?

This guide walks through the seven most common reasons for solar panels not producing enough, the quick test for each, the fix, and when to stop troubleshooting and call a professional.

1. Shade on the Panels

Shade is the number one thief, and the most common reason for solar panels not producing enough. Even a small patch of shade from a growing branch or a new vent can drag down a whole string because panels in series are only as strong as their weakest performer. The quick test: look at your roof at 9 am, noon, and 4 pm and photograph what you see.

The fix: trim the tree, move the satellite dish, or if shade is unavoidable, ask a professional about micro-inverters or power optimizers that let each panel work independently. If you are planning a system and want it sized for your roof from the start, our sizing guide for a 1,500 sq ft home walks through the maths.

2. Dirt and Debris

Dust, pollen, bird droppings, and leaves form a film that blocks light. In dry climates, losses of 5-15% are common. The quick test: compare this month’s production to the same month last year. A slow drift downward with no weather change points to grime. The fix: rinse the panels with a garden hose on a cool morning, never a pressure washer, and avoid walking on them. Steep roofs or stubborn buildup are jobs for a professional cleaner. A quick read of our cost of cleaning solar panels guide tells you what fair pricing looks like.

3. Inverter Faults

Your inverter turns panel DC power into the AC your home uses, and when it sulks, everything drops. Red or orange status lights, error codes, or a flatline in the monitoring app are the giveaways of solar panels not producing enough. The quick test: check the inverter display and your app for fault messages. The fix: many faults clear after a proper reboot following the manufacturer’s sequence. If errors persist, this is firmly call-the-installer territory. Inverters are the brain of the system; do not open them yourself.

4. Age-Related Degradation

Panels lose a little output each year, typically around 0.5% annually for modern modules. A 10-year-old system should still produce roughly 95% of its original rating. The quick test: compare year-over-year production for the same months, adjusted for weather. A sudden drop is a fault; a gentle slope is normal ageing. The fix: there is no reversing degradation, but keeping panels clean and cool squeezes the most from them. If output has fallen far below the warranty curve, file a warranty claim with your installer or manufacturer.

5. Weather and Seasonal Changes

Winter production can be a third of summer’s. Shorter days, low sun angles, snow cover, and overcast stretches all cut output, and this is normal, not broken. The quick test: compare against the same month in a previous year, not against July. Solar panels not producing enough compared with last December is a red flag; compared with July, it is normal. The fix: manage expectations first. If you live with heavy snow, consider panels with steeper tilt or snow guards so slides clear naturally. Track monthly trends so you can spot the difference between seasonal dips and real problems.

6. Faulty Wiring or Connections

Loose MC4 connectors, chewed cables, or corroded junction boxes create resistance and hot spots that silently eat production. The quick test: in the app, look for one string or panel consistently underperforming its siblings. The fix: do not climb up and start unplugging things. Wiring faults are a fire risk. Book an inspection with a certified solar technician who can thermal-image the connections and replace damaged parts safely.

7. Monitoring App Glitches

Sometimes a report of solar panels not producing enough is just the app lying: the panels are fine, and the data is stale. Offline gateways, stale data, or a firmware update can show flat production when the system is actually humming along. The quick test: check whether the inverter’s own display or a utility meter shows generation while the app shows nothing. The fix: restart your router and the monitoring gateway, re-pair the connection, and check for pending firmware updates. If the data gap persists beyond a day, contact the monitoring company’s support. The U.S. Department of Energy also publishes homeowner resources on understanding residential solar performance data.

When to Call a Professional

Call a certified solar installer or electrician when: you see error codes that survive a reboot, production has dropped more than 20% year over year, you smell burning near the inverter or smell nothing but see scorch marks, or any fix requires touching wiring. Electrical work on a live DC system is not a weekend project. Get quotes from two or three local installers, and ask each what their diagnostic fee covers when solar panels are not producing enough without an obvious cause.

FAQ

Why are my solar panels not producing enough all of a sudden?

Sudden drops usually mean an inverter fault, a tripped breaker, or new shade. Check the inverter display and monitoring app first, then walk the roof line for anything new blocking the sun.

Can dirty solar panels really cut output that much?

Yes. Studies and installer data show 5-15% losses from heavy soiling in dry climates, and bird droppings on a single cell can hurt a whole string. A seasonal rinse is cheap insurance.

How do I know if my panels are underperforming or if it is just winter?

Compare the same month across years, not summer to winter. If this December matches last December, the system is behaving. If it is 20% lower, investigate.

Will my panels ever get back to 100% output?

Probably not, and that is by design. A small annual degradation rate is normal. Cleaning, trimming shade, and fixing faults return you to the expected curve, not above it.