Solar Panels Not Producing Enough Energy? Here's Why

You installed solar panels with expectations of lower electric bills and energy independence. But when you check your monitoring app, the production numbers feel off. Your installer promised 25 kWh per day, but you're consistently getting 15-18 kWh. What's going wrong?

Low solar production is one of the most frustrating issues homeowners face because there are multiple potential causes — and not all of them are obvious. The good news is that most cases of low production are fixable once you identify the root cause.

Cause #1: Shading on Your Panels

This is the #1 cause of low solar production. Even partial shading — a tree branch, roof edge, or chimney shadow — can dramatically reduce energy output. Unlike traditional electrical systems, solar panels operate as a series circuit. If one panel is shaded and producing less current, it drags down the entire string of panels.

Modern systems with microinverters (Enphase) or power optimizers (SolarEdge) mitigate this by allowing each panel to operate independently. But even with optimized systems, shading still reduces your production.

How to check: Look at your roof from the ground during different times of day. Take note of any shadows falling across your array. If a tree is casting shadow, consider selective pruning. If a roof edge or chimney is the problem, unfortunately, your options are limited — relocation is usually not cost-effective.

Cause #2: Dirty Panels (Soiling)

Dust, pollen, bird droppings, leaves, and debris can accumulate on your panels and reduce output by 5-25% depending on the amount of soiling. This is especially problematic in dry climates where rain doesn't naturally wash panels clean.

A simple visual inspection will tell you if soiling is the issue. Look at your panels from the ground with binoculars — if you see dust or dirt buildup, that's your problem.

The fix is straightforward: clean your panels. For roof-mounted systems, hire a professional solar cleaning company (typically $200-400). For ground-mounted systems, you can often do it yourself with a soft brush and deionized water. After cleaning, your production should noticeably improve within days.

Cause #3: Inverter Problems or Configuration Issues

Your inverter is the device that converts DC electricity from your panels into AC electricity your home can use. If it's not working properly, production suffers. Common inverter issues include:

• Isolation faults — electrical leakage to ground from moisture damage or degraded insulation
• AC overvoltage — the grid voltage is too high, causing the inverter to shut down
• Overtemperature — the inverter is running too hot and throttling output
• Offline status — the inverter has lost connection to the grid or its monitoring system

How to check: Open your inverter monitoring app and look for error codes or warnings. Even if everything looks "normal," dig deeper — check that your inverter is actually online and not in a reduced-power state.

Cause #4: Panel Degradation or Internal Damage

Solar panels degrade at roughly 0.7-0.8% per year — this is normal and expected. However, if degradation is happening faster than normal, something might be wrong.

Cracked panels, delamination (layers separating), or internal corrosion can all accelerate degradation and reduce output. These issues often can't be seen from the ground but will show up as progressively declining production over months.

If you suspect panel degradation, a professional solar technician can perform an infrared scan of your array to identify damaged panels.

Cause #5: Incorrect System Configuration

Sometimes low production is due to installation errors. Your panels might be tilted at the wrong angle for your location, wired incorrectly, or not pointing in the optimal direction.

This typically shows up immediately after installation rather than developing over time. If your production has always been low, talk to your installer about whether the system design is right for your location.

How to Diagnose the Actual Problem

The fastest way to identify the cause of low production is to compare your actual output against what your system should theoretically produce for your location and weather conditions.

PVWatts is a free NREL tool that estimates solar production based on system size, location, tilt angle, and panel type. But it requires you to manually input data and do the math each month.

A better approach: use SolarDoctor. Connect your SolarEdge account and we automatically compare your actual production to what it should be, then give you a health score from 0-100. The score tells you instantly whether underperformance is a minor concern or a red flag that needs professional attention.

When to Call a Professional

If you've ruled out shading and soiling, and your monitoring app shows error codes, it's time to call a professional. A certified solar technician can:

• Use specialized equipment to test panel output and wiring
• Identify isolation faults with a megohmmeter
• Perform an infrared scan to detect failed or damaged panels
• Check inverter firmware and configuration settings

A typical diagnostic visit costs $300-500 but will save you thousands in lost production if it identifies a fixable problem.