How to Tell If Your Solar System Is Actually Underperforming

Once a solar system is turned on, it’s natural to wonder whether it’s doing what it’s supposed to do.

A cloudy week. A higher-than-expected bill. A dip in the monitoring app.

Not every concern means there’s a problem. In fact, most “underperformance” worries come from normal seasonal changes or billing timing—not system issues.

Here’s how to tell the difference between expected variation and a system that actually needs attention.

First: What Isn’t Underperformance

Before looking for problems, it helps to rule out what’s normal.

Your system is not underperforming just because:

• Production is lower in winter than summer

• Daily output changes from one day to the next

• Your first few bills still show utility charges

• Cloudy or rainy weeks reduce output
  
  

Solar production is variable by nature. A healthy system doesn’t produce the same amount of energy every day—or even every month.

What “Underperforming” Actually Means

A solar system is underperforming when it consistently produces significantly less energy than it was designed to, without a clear seasonal or environmental reason.

Key word: consistently.

Real underperformance shows up over time, not overnight.

Step 1: Look at the Right Timeframe

The biggest mistake homeowners make is evaluating performance too quickly.

Instead of daily or weekly numbers, focus on:

• Monthly production

• Year-to-date production

• Annual trends
  
  

If your system tracks reasonably close to projections over several months, it’s doing its job—even if some weeks look worse than others.

Step 2: Compare Against Expectations, Not Best Days

Every system is designed with:

• Historical weather data

• Roof orientation and tilt

• Shading considerations

• Utility rules and usage patterns
  
  

That means production estimates already assume:

• Winter lows

• Cloudy periods

• Seasonal swings
  
  

Underperformance isn’t about missing a perfect sunny-day number. It’s about missing reasonable, long-term expectations.

Step 3: Check for Real Red Flags

There are situations that deserve attention.

Extended Zero Production

If your monitoring shows zero output for multiple consecutive days during normal sunlight conditions, that’s worth investigating.

Sudden, Permanent Drops

A noticeable drop that never recovers—outside of seasonal change—can indicate equipment or connection issues.

No Credits Appearing Over Time

If production is visible in monitoring but net metering credits never appear after multiple billing cycles, clarification may be needed.

Utilities like Dominion Energy and Appalachian Power Company apply credits on specific schedules, so short delays are normal—but long-term absence isn’t.

Step 4: Separate Solar Production From Utility Bills

This is where many homeowners get tripped up.

Solar monitoring shows energy produced.

Utility bills show energy purchased from the grid, after credits and fees.

Because billing cycles lag production:

• A strong production month may not show up immediately

• A low bill doesn’t always match a high-production period

• A high bill doesn’t mean solar failed
  
  

Bills are part of the picture—but not the whole story.

Step 5: Account for Usage Changes

Sometimes the system didn’t change—the home did.

Common causes include:

• New appliances

• Electric vehicles

• Heating or cooling changes

• More people at home
  
  

If usage increases, solar may still be performing exactly as designed—it’s just offsetting a larger load.

When to Ask Questions (Without Panicking)

It’s reasonable to ask for clarification if:

• Monitoring data doesn’t make sense over multiple months

• Production is far below projections with no explanation

• Utility credits don’t appear after ample time
  
  

Asking questions is part of being an informed homeowner. Panic usually comes from looking at the wrong data in isolation.

The Big Picture

A well-functioning solar system is boring—and that’s a good thing.

It quietly:

• Produces energy when the sun is available

• Adjusts naturally to seasons

• Delivers results over time, not overnight
  
  

True underperformance is rare. Confusion is common.

Understanding the difference makes solar far easier to live with.

VirginiaSolar.org was created to give Virginia homeowners clear, unbiased information about solar—so decisions are made with confidence, not pressure.

Our Help Desk and resource library are here whenever you want to go deeper or ask questions.