Flat roof solar on a mid-century home can work well, but it raises questions a typical pitched-roof house doesn't. The roof is thin and low-slope, its edge is a defining line of the house, and on many post-and-beam homes the ceiling inside is the underside of the roof deck. Where the panels go, how they are attached and how the roof under them is built all matter more than usual.
The billing rules have also changed. This guide covers getting the roof ready, placing panels so they suit the architecture, where batteries can go, how California solar billing works as of November 4, 2026, and what to ask when you buy or sell a home that already has solar.
Start with the roof
Solar panels usually stay on a roof for many years, so it makes sense to deal with the roof first. The National Register nomination for Palo Alto's Greenmeadow tract describes a relatively thin roof structure with exposed beams, originally finished with tar and gravel. It notes that Eichler roofs have no attics and that the underside of the redwood tongue-and-groove roof decking is the ceiling, so roof attachments pass through the same boards you see from inside.
Palo Alto's Eichler design guidelines list roofing with a plain appearance as appropriate, including tar and gravel, single-ply, foam and composite shingles. They encourage owners to explore insulated roofing materials to improve energy efficiency, and they do not encourage standing-seam metal roofing on Eichlers. If you plan to add solar within a few years, ask your roofer how panel mounts will be flashed and sealed into the new roof, and ask a structural engineer or the solar designer to confirm the roof can carry the added load. For more on planning a reroof with other projects, see our Eichler renovation guide.
A City of Long Beach permit checklist based on the 2022 California Residential Code adds two roof rules that are easy to overlook: roof penetrations must be flashed and sealed, and the solar array must have the same fire classification as the roof assembly.
Placement, looks and fire access
Palo Alto's guidelines offer practical placement advice that works for mid-century houses in any city:
Install panels and skylights in ways that minimize their visual impact.
Whenever possible, place panels on the existing roof slopes so they don't interrupt the original roof form as seen from the street.
Choose panels that don't rise substantially above the existing roof.
On a flat roof, consider installing panels flat, or as far to the rear of the roof as possible.
Keep new skylights low in profile and on roof slopes that don't face the street.
The guidelines also note that once panels are installed, state law protects their access to sunlight. The sections they cite, Public Resources Code 25980 to 25986, are titled the Solar Shade Control Act, and they limit shading of installed solar collectors by trees and shrubs on another property. Our mid-century modern design guidelines page covers other rules that may apply to visible changes.
Firefighter access pathways. The residential code requires clear pathways through rooftop solar arrays on many roofs. The Long Beach checklist, written for the 2022 code, skips the pathway requirements when the roof slope is 2 units vertical in 12 horizontal (about 17 percent) or less. On steeper roofs it calls for at least two pathways at least 36 inches wide on separate roof planes, running from the lowest roof edge to the ridge. That matters for mid-century houses: flat and very low-slope roofs may avoid pathways, while gable roofs, which Palo Alto's guidelines say are often pitched at 3:12, may need them. The 2025 California codes took effect January 1, 2026, so confirm current requirements with your building department.
Where batteries can go
Some owners add a battery to store daytime solar power for the evening. A City of Monte Sereno handout on residential energy storage systems, based on the 2022 California codes, summarizes the location rules:
A permit is required before installation.
Allowed locations include detached garages and accessory structures, attached garages with the required separation from living space, exterior walls at least 3 feet from doors and windows that open into the home and not below sleeping-room escape openings, and enclosed utility closets or spaces lined with 5/8-inch Type X gypsum board.
Batteries are not allowed in sleeping rooms, in closets or spaces that open directly into a sleeping room, or in other habitable spaces.
Individual units are limited to 20 kWh, and combined ratings are capped by location, for example 40 kWh in utility closets, 80 kWh inside attached garages and 100 kWh on or within 3 feet of exterior walls.
Batteries in a spot where a vehicle could hit them need vehicle impact protection, such as bollards.
On a house with an open carport, wood siding and walls of glass, the allowed spots can be limited, so plan the battery location with your installer, and confirm the current 2025-code limits with your building department, before you sign a contract.
Solar billing rules as of November 4, 2026
PG&E customers. The California Public Utilities Commission adopted its Net Billing Tariff in Decision D.22-12-056 on December 15, 2022, as the successor to net energy metering. It applies to customers who submit an interconnection application on or after April 15, 2023, and a November 30, 2023 resolution made minor modifications. PG&E calls it the Solar Billing Plan. Under it:
Power you send to the grid earns an export credit that reflects its value at that time and varies by time of day, day of the week and season.
Residential customers are automatically enrolled in PG&E's Electric Home time-of-use rate and receive an annual True-Up statement.
Energy is typically more expensive from 4 to 9 p.m., and PG&E says the plan was designed in part to encourage battery storage.
An earlier PG&E FAQ on the plan says that if you connect a system by 2027, the value of your export credits is set for nine years.
City of Palo Alto Utilities customers. Palo Alto runs its own program. The city says it reached its first net metering cap on December 31, 2017, and that later systems are served by its NEM 2 program, which credits exported power at its Export Electricity Compensation (EEC-1) rate. The city's net metering page says the CPUC's tariff applies only to utilities the CPUC regulates, such as PG&E, and that the city currently has no plans to change its NEM 2 policy. Policies and rates can change, so owners in Palo Alto's mid-century neighborhoods should check the city's current NEM 2 terms and EEC-1 rate before sizing a system.
Federal tax credit. The IRS says the 30 percent Residential Clean Energy Credit covered qualified property installed from 2022 through December 31, 2025, and is not available for property placed in service after that date. Ask a tax advisor about your situation.
Buying or selling a home with solar
PG&E's FAQ says the 20-year legacy net metering rules are tied to the system, not the owner. If the original owner has used 15 of the 20 years, a buyer inherits the remaining five. When the legacy period ends, the account moves to the Solar Billing Plan at its annual True-Up. Expanding an older system beyond the tariff's limits, which PG&E's FAQ describes as 1 kW or 10 percent of system size, also moves it to the new plan. The same FAQ says customers who buy a building with an existing solar system aren't eligible for the plan's Energy Export Bonus Credit.
Useful questions for either side of a sale:
When was the system approved to operate, and which billing plan is it on?
Is the system owned, leased or under a power purchase agreement?
Were the panels, any battery and the roof work permitted and finaled?
How old is the roof under the panels, and what will it cost to remove and reinstall them at the next reroof?
Are recent True-Up statements available?
This is general information, not legal or tax advice. Check contracts with a real estate attorney, tax questions with a tax advisor, and code questions with your building department and a licensed contractor.
Frequently asked questions
Can you put solar panels on a flat Eichler roof?
Yes. Palo Alto's guidelines suggest installing panels flat or as far to the rear of a flat roof as possible to limit their visual impact. Plan the roof work and panel mounts together so the attachments are flashed and sealed into the new roofing.
Do flat roofs need firefighter pathways around solar panels?
A city permit checklist written for the 2022 code skips the pathway requirements on roofs with a slope of 2:12 or less. Steeper roofs, including many 3:12 gables, may need 36-inch pathways. Confirm the current rules with your building department.
If I buy a house with older solar, do I keep its net metering plan?
For PG&E customers, the legacy rules are tied to the system, so a buyer inherits the remaining years of the 20-year period. Expanding the system beyond the tariff's limits moves it to the Solar Billing Plan.
Is there still a federal tax credit for home solar?
The IRS says the Residential Clean Energy Credit is not available for property placed in service after December 31, 2025. Ask a tax advisor about any other incentives.
Related reading
Eichler Roof Replacement: Foam, Membranes and Above-Deck Insulation
Heat Pumps for Mid-Century Homes: Going All-Electric in the Bay Area
Thinking about solar on a mid-century home you own, or buying one that already has panels? Call or text the Boyenga Team at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team.
