Usually because the tariff you were put on credits exports below retail, or because consumption rose, or because the array is producing less than projected. Asking why your electric bill went up after solar is a diagnostic job with a short list of suspects, and they can be checked in order from cheapest to hardest.
The table below runs that list in the order worth working through it.
| Possible cause | How to check it | Difficulty |
|---|---|---|
| Export credit below retail rate | Compare export credit to import rate on the bill | Read the bill |
| Time-varying rate, evening-heavy usage | Look at usage by rate period | Read the bill |
| Consumption increased | Compare kilowatt-hours to the same month last year | Read the bill |
| Fixed and program charges unchanged | Find the flat lines on the bill | Read the bill |
| Rate increase since the projection | Compare the current rate schedule to the quote | One phone call |
| Production below projection | Check the monitor against the design estimate | Check the app |
| Shading or soiling | Look at the array and the production curve | Walk outside |
| Inverter or string fault | Look for error codes and dead strings | Possibly a service call |
A Quick Note
This is general information, not financial or legal advice. Rate structures, export credit rules and fixed charges are set by your state and utility and they change. Confirm your own tariff and rate schedule with your utility. Any inspection or repair involving wiring, roof access or the inverter belongs with a licensed professional.
Quick Answer
Start with the bill rather than the roof. Compare your export credit to your import rate, check usage by rate period, compare kilowatt-hours consumed against last year, and locate the fixed charges. Only then check the monitor for production shortfall, shading, soiling or an inverter fault.
Read the Bill Before You Look at the Roof
Most of these causes are visible on a statement and cost nothing to investigate. Climbing on a roof is the last step, not the first.
The two numbers that matter most are what you are credited per exported kilowatt-hour and what you are charged per imported one. If the first is well below the second, that alone can explain a bill that never fell the way it was supposed to.
The California Public Utilities Commission describes traditional net energy metering as crediting exports at the retail rates, and its net billing tariff as crediting them at a rate reflecting the value of that generation to the grid, usually lower than the retail rate.
A projection built on the first structure does not describe a bill under the second. Our guide to Arizona net metering and solar incentives covers a state that moved to an alternative compensation model.
The Timing Problem
Under time-varying rates, a household can export plenty and still pay a lot, because the exports happened in cheap hours and the imports in expensive ones.
The CPUC has described the net billing tariff as charging customers for grid electricity based on high differential time-of-use rates that vary by time of day.
So look at usage by rate period rather than at the monthly total. Evening-heavy consumption is the pattern that produces this complaint.
The fix is load shifting before it is anything else. Our guide to whether charging an EV at home raises your bill covers the largest shiftable load most homes have.
Consumption Often Rises After an Installation
This is the cause nobody expects and it is common. A household that generates its own power tends to use more of it.
Air conditioning set a degree cooler, a second refrigerator, a hot tub, a new vehicle, a pool pump running longer. Each is small and they add up.
Compare kilowatt-hours consumed against the same month a year earlier rather than comparing dollars. Dollars mix in rate changes and confuse the picture.
If consumption went up, the array did not underperform. Your baseline moved. Our guide to how many watt hours you need covers rebuilding that baseline honestly.
The Charges That Were Never Going to Fall
Fixed charges do not respond to generation. The meter charge, the customer charge and program charges sit on the bill regardless.
The CPUC discusses charges funding public purpose programs such as low-income assistance, energy efficiency programs and wildfire hardening costs, and charges of that kind are commonly structured so generation does not avoid them.
Some utilities also apply a minimum bill, which puts a floor under a light month.
None of that is a fault, and all of it should have been in the projection. Our guide to how long solar takes to pay off covers building a payback figure that includes them.
Now Check Production
Open the monitor and compare actual monthly production against the design estimate you were given. A shortfall is a different problem from a billing structure.
Look at the shape of the daily curve rather than the total. A clean curve that is uniformly low points at soiling or degradation, while a curve with a notch points at shading.
A string or panel reading zero shows up as a step change on a specific date, which is usually easy to spot in a year of data.
Dust and pollen build up faster than people expect. Our guide to how often to clean solar panels covers that, and our guide to how much shade affects solar panels covers why one obstruction can cost more than its area suggests.
Equipment Faults Worth Ruling Out
Inverters are the component that fails most often in a solar system, and a nuisance-tripping inverter loses production quietly.
Error codes, a dark display, or repeated restarts through the day are all worth reporting rather than watching.
A failed panel-level optimizer or microinverter takes one panel out, which is a small loss that persists indefinitely.
Monitoring that only reports system totals hides all of this. Our guide to why your inverter keeps shutting off covers the diagnosis, our guide to what breaks first in a solar system covers the likely order, and our guide to signs a solar panel is failing covers the module itself.
Rate Increases Since the Quote
Utility rates move, and a projection written against an older schedule stops describing your bill. This cuts both ways.
Higher retail rates make self-consumed solar more valuable, so an increase is not automatically bad news for the economics.
What hurts is a structural change: moving from retail-rate export credit to a value-based credit, or a new peak window that no longer matches your habits.
Ask the utility for your current rate schedule and tariff name in writing. Our guide to questions to ask a solar installer covers the questions that would have surfaced this before purchase.
Working It in Order
- Compare export credit to import rate. One line against another on the same bill.
- Break usage down by rate period. Find out whether the problem is timing.
- Compare kilowatt-hours to last year. Establish whether consumption moved.
- Total the fixed and program charges. Know the floor your bill cannot go below.
- Check production against the estimate. Monthly totals, then the daily curve shape.
- Inspect for shade and soiling. The two cheapest physical causes to fix.
- Escalate faults to the installer. Error codes, dead strings and warranty claims.
For tracking any of this properly, our roundup of solar monitoring and production meters covers panel-level and whole-system options, and our guide to whether solar panels need servicing covers the maintenance that prevents slow losses.
Frequently Asked Questions
Why did my electric bill go up after solar?
The common causes are an export credit below your import rate, evening-heavy usage under time-varying rates, consumption rising after installation, fixed and program charges that generation never offsets, a utility rate increase, or production falling short from shading, soiling or a fault.
What should you check first?
The bill, not the roof. Compare what you are credited per exported kilowatt-hour against what you are charged per imported one, break usage down by rate period, and compare kilowatt-hours consumed against the same month last year.
Can the tariff alone explain it?
Often yes. The CPUC describes traditional net metering as crediting exports at retail rates and its net billing tariff as crediting at a grid-value rate that is usually lower. A projection built on the first does not describe a bill under the second.
Why would my usage have increased?
Households that generate their own power tend to use more of it. A cooler thermostat setting, a second refrigerator, a hot tub, a new vehicle or a pool pump running longer each add a little. Compare kilowatt-hours rather than dollars to see it.
How do you tell shading from soiling?
Look at the shape of the daily production curve rather than the total. A uniformly low but clean curve suggests soiling or degradation across the array, while a notch or dip at a consistent time of day suggests an obstruction casting shade.
Could the inverter be the problem?
Yes, and inverters fail more often than panels. Error codes, a dark display or repeated restarts through the day all point there. A failed optimizer or microinverter quietly removes one panel, which is a small persistent loss.
Do fixed charges mean solar was a bad idea?
No, they mean the projection should have included them. Fixed monthly charges, program charges and any minimum bill survive any amount of generation, so they set the floor your bill cannot fall below.
Is a utility rate increase bad for solar?
Not necessarily. Higher retail rates make the energy you self-consume more valuable. What hurts is a structural change, such as moving from retail-rate export credit to a value-based credit, or a new peak window that no longer matches your habits.
Sources
- California Public Utilities Commission, net energy metering and net billing
- California Public Utilities Commission, net energy metering revisit frequently asked questions
