How Often Does Going Solar Require a Main Panel Upgrade? 24,491 Installs in Unincorporated LA County, 2020–2026
About one in ten. Of 24,491 solar installs on existing homes in unincorporated Los Angeles County from 2020 to August 2026, 9.6% listed a main panel upgrade in the solar permit itself. Counting upgrades filed on a separate electrical permit within four months of the solar permit, 23% — about 1 in 4 — went with a new main panel. Since net billing began for new applications in April 2023, systems with a battery listed an upgrade far more often (14%) than systems without one (5%).
A main panel upgrade (MPU) replaces the home’s main electrical panel, usually with a larger busbar, so the solar breaker fits within the electrical code’s limit on how much power can feed the panel. It adds cost and weeks to a project, and estimates of how often it is needed vary widely. Los Angeles County publishes every permit in its EPIC-LA system, and solar permits there usually describe the work, so the records show how often an upgrade actually came with the solar.
Year by year
Solar installs on existing homes by the year the permit was filed.
| Year filed | Solar installs | Listed in the solar permit | Including separate permits |
|---|---|---|---|
| 2020 | 2,324 | 8.7% | 21.7% |
| 2021 | 3,689 | 8.5% | 26.1% |
| 2022 | 5,813 | 10.8% | 26.5% |
| 2023 | 5,004 | 8.1% | 24.6% |
| 2024 | 3,605 | 12.4% | 21.9% |
| 2025 | 2,719 | 9.6% | 16.4% |
| 2026 | 1,337 | 7.3% | 12.3% |
| Recent years are incomplete on the separate-permit side: an upgrade filed after the data cutoff is not yet visible. | |||
https://cali-energy.com/research/solar-main-panel-upgrade-how-often-la-county. Aggregated data are free to use under CC BY 4.0 with a link to this page.By battery, tariff period and permit path
| Group | Solar installs | Listed in the solar permit | Including separate permits |
|---|---|---|---|
| No battery, filed before April 15, 2023 | 12,648 | 9.1% | 26.1% |
| With battery, filed before April 15, 2023 | 1,256 | 9.1% | 19.2% |
| No battery, filed from April 15, 2023 | 4,179 | 4.6% | 16.3% |
| With battery, filed from April 15, 2023 | 6,408 | 14.0% | 22.1% |
| Express permit path | 6,339 | 12.7% | 21.1% |
| Standard permit path | 18,152 | 8.5% | 23.7% |
| April 15, 2023 is when the Net Billing Tariff replaced NEM 2.0 for new applications; the date here is the county permit filing date. | |||
Since April 2023, when most new systems began to include storage, batteries made the biggest difference: 14% of battery systems listed an upgrade in the solar permit, three times the 5% of solar-only systems. A battery and its backup gateway add equipment to the service and can call for a new panel or a reconfigured one. Solar-only systems needed fewer upgrades after April 2023 than before (16% against 26% counting separate permits).
By system size
Where the permit states the size in kW.
| System size | Solar installs | Listed in the solar permit | Including separate permits |
|---|---|---|---|
| under 5 kW | 5,733 | 6.9% | 16.2% |
| 5–8 kW | 7,306 | 11.1% | 25.7% |
| 8–12 kW | 5,466 | 10.4% | 26.2% |
| 12 kW or more | 2,166 | 8.9% | 25.4% |
Small systems needed an upgrade least: 7% of systems under 5 kW listed one. A small inverter’s breaker is more likely to fit within the existing panel’s limit. Above 5 kW the share is roughly flat, largely because the panel limit, not the array size, decides: a 200 A panel with a 200 A main breaker can take a modest solar breaker, and beyond that the options are an upgrade, a derated main breaker or a supply-side connection.
Alternatives to a new panel
Derate the main breaker
A smaller main breaker frees room for the solar breaker when the load allows. See derate the main breaker, not the panel.
Supply-side connection
Tapping ahead of the main breaker avoids the busbar limit where the utility allows it.
A load calculation
Sometimes the numbers show no change is needed. See the derate that was not needed.
A bigger busbar
When the panel must go, a higher-rated busbar leaves room for solar and more. See a new panel with a bigger busbar.
The rule behind it and how to check your own panel: do you need a main panel upgrade for solar; other routes: solar without a panel upgrade and smart electrical panels.
Methodology
- Installs
- LA County EPIC-LA solar permits (roof-mounted residential and express solar, with or without storage) in unincorporated areas, filed January 2020 – August 2026, classified as a new system on an existing home by the method of our county solar permit study; one install per parcel per year. 24,491 installs.
- Upgrade listed
- The solar permit’s description names a main panel, main service panel or service upgrade or replacement (including MPU, MSP upgrade, a new main panel of a stated size), and does not negate it (“no MPU”, “existing MSP to remain”).
- Separate permits
- An electrical permit on the same parcel, filed within 120 days of the solar permit, whose description names a main panel or service upgrade. Such an upgrade may also have been done for an EV charger, an ADU or an old panel, so this is an upper estimate.
- Checks
- We read samples of the descriptions by hand: about 95% of flagged solar permits did describe a main panel upgrade, and a random sample of unflagged ones showed none missed after the rules were widened.
- Limits
- Unincorporated LA County only; cities with their own building departments, including the City of Los Angeles, are not covered. Home age and panel rating are not in the records.
Sources: LA County Public Works, EPIC-LA case history (open data), January 2020 – August 2026.
Frequently asked questions
How often does solar require a main panel upgrade?
In unincorporated LA County, 9.6% of solar permits for existing homes listed a main panel upgrade, and 23% of installs had one when separate electrical permits filed within four months are counted.
Do batteries make a main panel upgrade more likely?
Yes. Since April 2023, 14% of solar permits with a battery listed an upgrade, against 5% without one.
Does a bigger solar system need a panel upgrade?
Systems under 5 kW listed an upgrade least often (7%); above 5 kW the share was about 10% regardless of size.
Can I avoid a main panel upgrade for solar?
Often. A derated main breaker, a supply-side connection or a load calculation can keep the existing panel; see solar without a panel upgrade.
Is it true that 20–30% of solar installs need a panel upgrade?
It is close to the wide count in county records (23%), which includes separate upgrade permits. Counting only upgrades written into the solar permit gives 10%.
More research
Next steps
Not sure your panel can take solar?
Prepared by Cali Energy, October 15, 2026. Figures describe public permit records and are not a guarantee of what any specific roof will produce; orientation, tilt, shade, equipment and weather change results. Not engineering, financial or utility advice. See our Content Disclaimer.