Solar in Sonoma County

What you get paid for exported power, and why design changed

For the PG&E-connected majority of the county, the rules are the CPUC's. Under the Net Billing Tariff, compensation for exported generation is applied "at a rate reflecting the value of this generation to the grid," the earlier net metering tariffs are "closed to new enrollments," and onsite generation "is first used to serve onsite load."

Strip the jargon and one design consequence falls out. A kilowatt hour you consume the moment you make it is worth what you would otherwise have paid for it. A kilowatt hour you send back is worth what the grid says it is worth at that instant, which on a sunny Sonoma afternoon is not much, because everyone else's array is producing too.

That reorders the design questions:

Those last two are different projects. A battery sized to trim an evening peak and a battery sized to keep a well pump, a refrigerator and a heat pump alive through a multi-day outage are not the same piece of equipment. Sizing for one and expecting the other ends in disappointment with a system that is working exactly as specified.

Where the permit is genuinely fast, and where it is not

State law has been steadily removing local discretion from solar permitting, and this county now shows the full range of results.

The baseline is Government Code 65850.5, which requires every city and county to "adopt an ordinance...that creates an expedited, streamlined permitting process for small residential rooftop solar energy systems," to publish "a checklist of all requirements," to deem a conforming application complete, and to "allow for electronic submittal of a permit application and associated documentation."

SB 379 went further. Per the California Energy Commission, it "requires most California cities and counties to implement an online, automated permitting platform that verifies code compliance and issues permits in real time" for a residential system "no larger than 38.4 kilowatts alternating current." The CEC publishes a dashboard of which jurisdictions have done it.

Rohnert Park is a good example of what that looks like in practice, and of its limits. The city offers automated permits for residential rooftop solar including storage, but states that "automated solar permits are only available for rooftop systems located on single-family homes and duplexes" and that "other types of solar projects must submit for an Electrical permit through the City's eTRAKiT system." So a rooftop array on a single-family house may be issued in real time, while a ground mount on the same parcel drops back to an ordinary electrical permit. That is a meaningful difference on a rural lot where the ground mount was the better design anyway.

Outside the nine incorporated cities, Permit Sonoma has jurisdiction, and it "reviews, permits, and inspects" development throughout the unincorporated area. Its building and construction permits section publishes dedicated guidance for solar permits and, separately, a back-up generator checklist for a unit connected to your electrical panel, which is worth being aware of if storage and a generator are both under consideration.

Two things streamlining does not do. It does not remove the permit, and it does not touch the interconnection. Permission to operate runs on the utility's clock, not the building department's, and the gap between a finished installation and a legally producing system is set far more by that sequence than by anything a crew does on a roof.

What the county's own geography does to a design

Sonoma County is the largest area we cover and the least uniform, and the variation is not really about sunshine.

Inland heat aligns production with load. Santa Rosa, Rohnert Park, Windsor and the Sonoma Valley run genuinely hot summer afternoons, which is when an array produces most and when a heat pump works hardest. That alignment is the strongest argument for solar in this county and it gets stronger as households electrify heating.

West county trades sun for canopy. Toward Sebastopol, Occidental and the lower Russian River, redwood and fir cover changes the calculation from orientation to shading, and shading has to be measured on the roof rather than estimated from an aerial image. Tree growth also means a model built on today's canopy reads optimistic in five years.

Rural parcels change the whole scope. A long service drop from the road, a detached shop or barn on its own feed, a well pump that has to keep running, and frequently enough open ground that a ground mount beats the roof outright. On these properties the property sets the design, not the house.

Older town cores set the electrical constraint. On the pre-war streets of Petaluma, Santa Rosa and Sonoma we routinely find services sized for a much shorter appliance list and panels with nothing left to give. That is the step that turns a solar quote into a solar-and-panel quote, and it is the same electrical work whichever way the array is laid out.

The air district line runs through this county, and it changes what you electrify next

Solar rarely arrives alone. It usually arrives alongside a heat pump, a heat pump water heater or a charger, and in Sonoma County the rules for those are not the same countywide.

The county publishes the split on its air quality districts page. The Bay Area Air Quality Management District "extends throughout the southern portion of Sonoma County including Bloomfield, Cotati, Glen Ellen, Graton, Kenwood, Penngrove, Petaluma, Rohnert Park, Santa Rosa, and Sonoma," while the Northern Sonoma County district covers the northern and coastal region including Cloverdale, Geyserville, Guerneville, Healdsburg, Jenner and The Sea Ranch. Windsor, Sebastopol, Occidental and Valley Ford are each partly in both.

Inside the Bay Area portion, the district's building appliance rulemaking phases zero-NOx standards in on three dates: 2027 for small tank-type water heaters up to 75,000 BTU per hour, 2029 for furnaces below 175,000 BTU per hour, and 2031 for larger tanks and tankless units. It governs sale and installation of new equipment, and the district states its amendments "do not mandate retrofitting of existing appliances." North of the line those dates do not apply, and the northern district publishes no equivalent residential rule of its own.

The practical point for a solar customer is sequencing. If a heat pump is coming after the array, the panel work is best sized once for both rather than twice.

What the number is built from

The roof first. Age and remaining life, covering type, pitch, how many usable planes it has, and how much of it is lost to vents, chimneys and skylights. Tile has to be lifted and reset around every mount. An array on a roof with a few years left is a cost paid twice, because removing and reinstalling it later is far cheaper to schedule than to discover.

The service second. Panel capacity, busbar rating, available breaker space, and whether the interconnection lands as a load-side breaker, a busbar-rated arrangement or a connection ahead of the main. This is the item that most often changes the scope.

Then storage, if it is in the design. Battery count, where it can legally and sensibly sit, and whether a critical-loads subpanel is needed, which it usually is if the goal is riding out an outage rather than trimming a bill.

Then access and distance. Two-story with limited setbacks, a long conduit run from a detached structure, a trench across a driveway that has to be restored.

And the permit route, which in this county can mean a real-time automated issuance or an ordinary electrical permit depending on the city and the mounting type.

An array fails quietly

Nothing on a roof announces a fault. A failed optimizer, a string that dropped offline, a rodent nest under the modules, a slowly shading branch: none of them make a noise, and none of them show from the ground. The system simply makes less, and the bill creeps up in a way most households attribute to rates.

So monitoring is the maintenance, and reading it seasonally rather than glancing at it is the actual discipline. Compare this June against last June, not against May.

The rest is short. Winter rain does most of the panel cleaning in this county, though not all of it and not in a dusty summer. Keep battery firmware current and the warranty registered, and remember that a battery which has never been asked to discharge is not evidence that it will. On the installation side, we fit critter guards at the outset, since in the wooded parts of the county rodents get under most arrays, and we flag a roof near replacement age before the system goes on, because installing on a new roof is far cheaper than lifting an array off an old one. Our maintenance program covers the home's mechanical and electrical systems.

Where we work across the county

Everything is dispatched from the Petaluma headquarters at the county's southern end. We cover the incorporated cities and the unincorporated areas between them, from Petaluma and Cotati up through Rohnert Park, Santa Rosa, Windsor and Healdsburg to Cloverdale, west through Sebastopol toward the coast, and east into the Sonoma Valley.

The wider county picture is on the Sonoma County service area page, and the other trades have their own county views: heating and cooling, plumbing and electrical. Our county-wide solar work covers Marin and Napa as well.

How to choose a solar contractor here

Ask who holds the license and who will be on your roof, because in this trade the two are often different companies. Ask whether the electrical scope is in house or subcontracted, since the service work is where the surprises live. Ask who files the interconnection application and who chases permission to operate. Ask what happens if the load calculation says the panel needs work, and whether that is inside the quoted price or outside it. Ask whether the design assumes a PG&E interconnection, and if your address is in Healdsburg, ask again.

Then ask who answers the phone in year six. We hold the C-10 electrical, C-20 HVAC and C-36 plumbing classifications, and we are Diamond Certified with a BBB A+ Rating. A family business working here since 1932 is a reasonable answer to that last question.