If you’ve recently gone solar and noticed that your utility bill doesn’t match the numbers in your solar monitoring app (like Enphase), you’re not alone. One of the most common questions solar customers ask is: “Why does my bill say I used electricity when my system shows it produced more than that?” The answer lies in how net metering works.
What Is Net Metering?
Net metering is the billing system that tracks the exchange of energy between your solar system and the utility grid. Here’s how it works:
- When your solar system is producing energy (mostly during the day): That energy is used immediately to power your home. Any extra solar energy that your home doesn’t use is sent to the grid. These are called excess generation credits.
- When your system isn’t producing enough (like at night or during winter): You draw electricity from the grid. That usage is tracked as net consumption.
At the end of each billing cycle, your utility subtracts the excess generation from your net consumption to calculate how much grid energy you used overall. If you sent more to the grid than you used, the leftover becomes a credit that carries forward.
Why Your Bill Doesn’t Match Your Solar Production
Your solar monitoring platform (like Enphase) shows total solar production—that’s how much energy your panels generated. But your utility bill shows your net usage—how much electricity you had to buy from the grid after using your solar in real-time.
So even if your system produced 500 kWh in a month, you might still see 100 kWh of usage on your bill. Why? Because:
- You might have used some power at night (when the sun’s down).
- You could be charging an electric car or running large appliances overnight.
- Your system’s excess generation during the day wasn’t enough to fully offset your nighttime use.
The Seasonal Credit Cycle (and Why It Resets in March)
Oregon utilities like PGE operate on an annual net metering cycle that ends each March. This is often called the true-up.
Here’s how it works:
- In the summer, your system produces more than you use. You build up a bank of energy credits.
- In the winter, when production drops, you use those credits to cover your needs.
- In March, the credit bank resets to zero. If you have any leftover credits, they’re donated to programs that support low-income households.
Why You Might Have a Bill in Winter—Even If Your System Was Designed for 100% Offset
This is one of the most common points of confusion for new solar customers. Your system may have been designed to cover your annual electricity usage, but your billing is still tracked monthly until you reach your first full true-up in March.
If your system was turned on in late summer or fall, you only caught the tail end of the high-production season. That means you didn’t have time to build up a full bank of credits before winter arrived. So while your system may be producing exactly what it should on paper, you’re still dependent on the grid in the winter because the credit bank simply didn’t have enough stored up to get you through.
This often results in one or two bills in the late winter months—even for systems designed to offset 100% of your energy usage. It’s a timing issue, not a system performance problem.
The good news is that after your first full cycle (spring through the following March), the pattern smooths out. You’ll build credits all summer, draw on them in the winter, and the system will balance out as intended over the year.
Realistic Example: How It All Adds Up
Let’s say over the course of a year:
- Your system produces: 10,800 kWh
- Your home uses: 12,000 kWh
- You export to the grid: 6,000 kWh (excess generation)
- You import from the grid: 7,200 kWh (net consumption)
The utility will subtract the 6,000 kWh you gave them from the 7,200 kWh you took, leaving 1,200 kWh that you’re billed for across the year. If your solar system was designed to offset 90% of your usage, this is exactly what you should expect.
Why Grid Charges Still Show Up
Even if your system is performing perfectly, you may still see small utility charges:
- Time-of-day usage: Solar doesn’t cover your nighttime needs.
- Late-year startup: No time to build summer credits before winter hits.
- High usage: Electric vehicles, hot tubs, or electric heating systems can push your usage higher than what solar was designed to offset.
Final Thoughts
Your solar system might be producing exactly as expected—or even better—but utility bills don’t show solar production. They only show how much energy you drew from the grid after using your own solar power. That’s why they rarely match up.
Understanding how net metering and credit banking works—especially the March reset—can clear up a lot of confusion.
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