How should I wire solar panels for longer outage backup time?

Wire your solar array to match the voltage and current window your inverter and battery are designed for, often using series or series-parallel strings sized by an engineer. A properly designed configuration reduces losses and helps your battery recharge more quickly during limited daylight in extended outages.

Can I mix series and parallel wiring in one solar array?

Yes, many residential systems use a series-parallel layout where groups of panels are wired in series and then combined in parallel to balance voltage and current. This approach handles roof layout constraints or shading while still meeting the inverter's required voltage range.

What happens if my solar wire gauge is undersized?

Undersized wire can overheat, waste energy as heat, and create fire hazards — especially in high-heat areas like Sonoma County. It may also cause voltage drop that reduces system performance and can lead to code or warranty issues if it does not meet National Electrical Code requirements.

When is an AC-coupled battery better than a DC-coupled battery?

AC-coupled batteries are often the better choice when adding storage to an existing solar system because they tie into the AC side with fewer changes to array wiring. They also provide flexibility for future expansion, even if their round-trip efficiency is typically a bit lower than DC-coupled systems.

How many kilowatts of solar do I need for a 10 kWh battery in Sonoma County?

Pairing a 10 kWh battery with roughly 3–5 kW of solar can allow a full recharge in a single sunny day, assuming typical household use and good orientation. Final sizing is adjusted for climate, shading, and usage patterns.

Do I need a special inverter for battery backup?

Yes, whole-home or partial backup systems typically use a hybrid inverter or a dedicated battery inverter that can isolate critical loads when the grid fails. This equipment must be compatible with your wiring configuration, battery chemistry, and local interconnection rules.

How does wildfire smoke and heat affect solar wiring and batteries?

High temperatures can reduce panel efficiency and increase stress on wiring and connectors, while smoke can lower production and extend recharge times after an outage. Designing for proper wire gauge, ventilation, and realistic energy budgets helps maintain reliable backup during wildfire season.

Can I expand my battery or add more panels later?

Many systems are designed with extra inverter and wiring capacity so you can add more storage or panels in the future. Planning for expansion up front helps avoid costly rewiring and keeps your system flexible as energy needs change.

Federal Solar Tax Credit 2026: Sonoma County Guide

The 30% federal Residential Clean Energy Credit (Section 25D) expired on December 31, 2025, after President Trump signed the One Big Beautiful Bill Act (OBBBA) into law on July 4, 2025. Sonoma County homeowners who installed solar before that date can still claim the credit on their 2025 tax return using IRS Form 5695. Those installing in 2026 no longer qualify for the federal credit but have access to California’s SGIP battery rebate and other state-level incentives.

The 30% federal solar tax credit (Section 25D) is gone for homeowners as of January 1, 2026
If your system was installed by December 31, 2025, you can still claim it on your 2025 federal return via IRS Form 5695
Unused 2025 credit carries forward indefinitely until fully claimed, no expiration on carryforward amounts.
Solar leases and PPAs still benefit indirectly from commercial tax credits through installer pass-through savings.
Sonoma County homeowners in PG&E High Fire Threat District Tier 2 or 3 zones may qualify for SGIP battery rebates up to $1,000/kWh
California’s property tax exclusion for solar systems remains in effect through end of 2026.

If you installed solar panels on your Sonoma County home before December 31, 2025, you are eligible for a 30% federal tax credit worth thousands of dollars, but the window to act on it through your 2025 tax return is now. For homeowners planning a new installation in 2026, the federal credit is gone. This guide explains who can still claim it, how to file correctly, and what solar incentives remain available in Sonoma County right now.

Did the 30% Federal Solar Tax Credit Expire in 2026?

Yes. The Section 25D Residential Clean Energy Credit expired for expenditures made after December 31, 2025. The One Big Beautiful Bill Act, signed July 4, 2025, terminated this credit immediately without a phase-down period.

For a decade, Section 25D gave homeowners a 30% credit on the full installed cost of solar panels, battery storage, and related equipment, with no dollar cap. The Inflation Reduction Act had previously extended it through 2034. That extension was overturned by the OBBBA.

Key facts about the expiration:

No phase-down: the credit went from 30% to 0% in a single step after December 31, 2025
Applies to solar panels, solar water heaters, geothermal heat pumps, and battery storage
The IRS has updated its official guidance, the credit is no longer available for 2026 installations
IRS Form 5695 Instructions for 2025 confirm: “You can’t claim residential clean energy credits for expenditures made after December 31, 2025”

Who Can Still Claim the 30% ITC in 2026?

If your solar system was installed and placed in service by December 31, 2025, you can still claim the credit, even if you file your return in 2026.

Claiming is done on your 2025 federal tax return. The “expenditure made” rule refers to when your system was installed and operational, not when you paid or when you file.

Eligibility checklist for Sonoma County homeowners:

System was installed and operational on or before December 31, 2025
You own the system (purchased with cash or a loan, not a lease or PPA)
The home is your primary or secondary U.S. residence
You owe federal income taxes (the credit is non-refundable)
System was brand new at time of installation (used equipment does not qualify)

What about carryforward credits? If your 2025 credit amount exceeds what you owe in taxes this year, the unused balance carries forward to 2026, 2027, and beyond. The carryforward provision under Section 25D(c) was not changed by the OBBBA.

How to File IRS Form 5695 for Your Solar Installation

File IRS Form 5695, Residential Energy Credits, with your 2025 federal tax return to claim the 30% solar credit.

This is the only form needed. Most tax software handles it with step-by-step prompts. If you installed solar in 2025 and have not yet filed your return (or filed an extension), complete these steps:

Step	What to Do
1	Confirm installation was completed by December 31, 2025
2	Locate your final invoice showing the total installed system cost
3	Complete IRS Form 5695, Part I (Residential Clean Energy Credit)
4	Enter total system cost on Line 1; your 30% credit calculates on Line 6b
5	Enter your final credit amount from Line 15 onto Schedule 3 (Form 1040), Line 5a
6	If credit exceeds tax owed, carry the remainder forward to next year’s return via Line 16

Eligible costs include solar panels, inverters, mounting hardware, labor for installation, and wiring. Do not include loan interest or general roof repair costs.

Figures may vary. Verify with a licensed tax professional before filing.

What Solar Incentives Are Still Available in Sonoma County in 2026?

Sonoma County homeowners installing solar or battery storage in 2026 have three meaningful programs available: SGIP, California’s property tax exclusion, and indirect savings through solar leases or PPAs.

The federal residential credit is gone, but California has not stepped back. Here is what remains active:

California SGIP (Self-Generation Incentive Program)

SGIP is now the most significant remaining solar incentive for California homeowners. It covers battery storage systems through PG&E, which serves Sonoma County.

SGIP Tier	Rebate Amount	Who Qualifies
General Market	~$150/kWh	All PG&E residential customers
Equity	$850/kWh	Households below 80% of area median income
Equity Resiliency	$1,000/kWh	Income-qualified + Tier 2/3 HFTD or 2+ PSPS events
RSSE (AB 209)	$1,100/kWh	Income-qualified; currently waitlisted

Much of Sonoma County falls within PG&E’s Tier 2 or Tier 3 High Fire Threat District zones, which means many local homeowners qualify for the $1,000/kWh Equity Resiliency rebate. On a 13.5 kWh battery system, that equals $13,500 in rebates.

California Property Tax Exclusion

Solar installations in California are excluded from property tax reassessment under the Active Solar Energy System Exclusion. Adding solar will not increase your property taxes. This exclusion is set to expire after 2026, so installations completed this year still benefit.

Solar Lease and PPA Pass-Through Savings

Homeowners who do not purchase their system outright can still access indirect incentive savings. Installers using third-party ownership structures can claim commercial credits, and competitive deals typically pass a portion of those savings to customers through lower monthly payments.

Is Solar Still Worth It in Sonoma County Without the Federal Credit?

Yes, for most Sonoma County homeowners, solar still delivers strong long-term savings, especially when paired with battery storage under NEM 3.0.

California is now operating fully under NEM 3.0, which reduced export compensation to the grid by roughly 75% for new solar-only systems. This makes battery storage central to the financial case for solar.

Why solar still makes sense in 2026:

PG&E rates in Sonoma County continue to rise; solar locks in your energy cost
Battery paired with solar lets you self-consume your production instead of exporting at low rates
SGIP offsets battery costs significantly for eligible homeowners
Solar’s property tax exclusion means no added tax burden through at least 2026
Payback periods without the federal credit are longer, but still favorable given rising utility rates

Frequently Asked Questions

Can I still claim the 30% solar tax credit if I installed in 2025 but have not filed my taxes yet?

Yes. If your system was installed and operational by December 31, 2025, you can claim the credit on your 2025 federal return using Form 5695, regardless of when you file.

Does Sonoma County have its own solar rebate program in 2026?

No county-specific solar rebate exists for Sonoma County. The primary programs available are the state-run SGIP through PG&E and California’s property tax exclusion. Contact Suntegrity Solar to verify current program availability for your address.

Can I carry forward unused solar tax credit from 2025 into 2026 or later?

Yes. The carryforward provision under Section 25D(c) was not changed by the OBBBA. If your 2025 credit exceeds your tax liability, the unused amount carries forward indefinitely until fully used.

Does the federal solar tax credit apply to solar leases or PPAs?

No. The Section 25D credit only applied to homeowner-owned systems purchased with cash or a loan. Lease and PPA customers do not qualify for the residential credit directly.

What is the SGIP rebate and how do I apply in Sonoma County?

SGIP is a California battery storage rebate administered through PG&E. Rebates range from approximately $150/kWh up to $1,000/kWh for homes in high fire threat zones. Your installer handles the application. Request a free quote from Suntegrity Solar to find out what tier your home qualifies for.

Conclusion

Sonoma County homeowners who installed solar by December 31, 2025 should file IRS Form 5695 with their 2025 tax return, there are thousands of dollars on the table. For new installations in 2026, the federal credit is gone, but SGIP battery rebates, California’s property tax exclusion, and strong long-term savings from battery-paired solar still make the investment worthwhile.

Get solar assessment from Suntegrity Solar to see exactly what today’s incentives mean for your home.