Dirty Panels Effect
Do Dirty Solar Panels Affect Your PG&E Bill? Here’s the Truth for Fresno Homeowners
If you’re a Fresno homeowner who’s gone solar, you’re likely enjoying the perks: lower PG&E bills, energy independence, and a cleaner footprint.
But lately, you may have noticed something frustrating:
“Why is my PG&E bill creeping back up?”
One of the most common — and overlooked — reasons is dirty solar panels.
In this guide, we’ll explore:
How dirt and debris reduce solar performance
Why it leads to increased PG&E charges under NEM 3.0
How much money you could be losing every month
And what Fresno homeowners can do to prevent it
☀️ Your Panels Aren’t Just Dirty — They’re Underperforming
Solar panels rely on unobstructed sunlight to generate electricity through photovoltaic (PV) cells. Even a thin layer of dirt, dust, or pollen can reduce the sunlight reaching these cells, directly lowering the system's efficiency.
In Fresno’s dry, agricultural environment, panels accumulate grime much faster than in coastal regions. If your panels haven’t been cleaned in 6 months or more, you could be producing 15–25% less power than your system is capable of.
That shortfall in production means your household will rely more on PG&E’s grid — defeating the purpose of going solar.
💡 How PG&E Bills Rise With Dirty Panels (NEM 3.0 Breakdown)
California’s Net Billing (NEM 3.0) system means you now save the most by using your solar energy in real time, rather than selling it back to the grid.
But when your panels are dirty:
They produce less power, especially during the afternoon peak
Your household pulls extra electricity from PG&E
You export less excess power, resulting in fewer credits
You lose savings on both sides: less generation and more consumption
This combination often leads to confusion for solar users: "Why am I still paying PG&E if I went solar?"
Dirty panels are frequently the cause.
🧾 The Real Cost of Dirty Panels in Fresno
Let’s run a basic estimate for a Fresno homeowner with a 7 kW solar system:
Expected production (clean): 1,050 kWh/month
Dirty panels reduce efficiency by 15% = 893 kWh/month
Energy shortfall: 157 kWh
PG&E peak rate: ~$0.30/kWh
Extra PG&E charge: $47/month, or $564/year
That’s over $500 a year in lost savings — simply because of dirt, bird droppings, and ash.
🏜️ Why Fresno Solar Panels Get Dirty Faster
Fresno’s Central Valley environment creates ideal conditions for rapid buildup:
1. Agricultural Dust
Dust from local farms and fields travels on the wind and settles on rooftops — including your panels.
2. Wildfire Ash
During fire season, even if you’re miles away from the flames, your panels can still collect a fine coating of gray ash that’s sticky and acidic.
3. Bird Droppings and Pollen
Spring and early summer bring an influx of both. Tree pollen builds up quickly, and birds nesting under or around panels leave droppings that can corrode surfaces and block entire cells.
4. Low Rainfall
Fresno only gets around 11 inches of rain per year. That’s not enough to naturally rinse panels — and when it does rain, it often just creates streaks.
🧰 Why Professional Cleaning Beats DIY
Cleaning your own panels sounds simple — but doing it wrong can lead to injury or costly damage. Here’s what to consider:
🧗 Safety Risks
Getting onto a hot rooftop with a hose and brush is dangerous. Sloped surfaces and slippery tools can lead to falls.
🚿 Hard Water Issues
Fresno’s tap water is mineral-rich. When sprayed on panels, it can leave white spots that reduce performance and require even deeper cleaning later.
❌ Wrong Tools Can Void Warranties
Using abrasive sponges, window cleaner, or high-pressure washers can scratch the surface and damage internal components — potentially voiding your warranty.
✅ What One Sun Solutions Does Instead:
Uses deionised water (no minerals, no streaks)
Soft-bristled, solar-safe brushes
Roof-safe protocols and proper harnesses
Visual inspection of mounts, wiring, and sealants
Optional system performance check
🔍 How to Know If It’s Time to Clean
Use Your Monitoring App
Check your energy production. If it’s significantly lower than the same period last year (and weather conditions are similar), dirt may be the cause.
PG&E Bill Rising?
If your PG&E bill is going up without major changes in energy use, check your solar output.
Visual Cues
From the ground, you may be able to see a cloudy film, droppings, or dark smudges on your panels. These are signs of blocked sunlight — and lost efficiency.
Rule of Thumb
In Fresno, clean your panels every 6 months minimum. Homes near farms, trees, or dusty roads may need quarterly cleaning.
✅ Final Word: Don’t Let Dirty Panels Drain Your Solar Savings
You installed solar to save money and take control of your energy future — but that plan only works if your system is running at full capacity.
Dirty panels can:
Reduce energy production by 15–30%
Cause you to rely more on PG&E
Shorten panel lifespan through overheating and corrosion
Void warranties if improperly maintained
