Licensed C-10 Electrical Contractor #989290 · Novato, CA
(415) 419-5960
Residential · Pillar Guide · PSPS-ready
Backup power that actually starts when PG&E doesn't.
PSPS events, atmospheric rivers, transformer failures — Marin has gotten used to its lights going out. A properly sized and installed standby generator turns a multi-day inconvenience into a quiet four seconds. Here's everything you need to specify, install, and live with one.
A standby generator is a permanently-installed, automatic system on a pad — fundamentally different from a portable generator. It runs on your existing natural gas or a dedicated propane tank, and starts within 10-15 seconds of an outage.
Sizing is the most consequential decision, and the most commonly wrong one. A 'whole-home' generator that's actually undersized for your loads will surge-trip in real-world use; an oversized one wastes capital and burns more fuel.
The Automatic Transfer Switch (ATS) is the brain of the system. It isolates your home from the utility, starts the generator, and reconnects when utility power is stable — all without you doing anything.
Marin's PSPS events have changed the math on residential generators. Multi-day outages have become routine in the dry season, and standby fuel supply (natural gas vs. propane) is one of the biggest planning factors.
Permits, gas hookup coordination, and AHJ inspection are all required; this is not a job for a handyman or a generalist contractor.
01 — OverviewWhat a whole-home backup generator actually does.
A whole-home backup generator — properly called a residential standby generator — is a permanently-installed system that sits on a concrete or composite pad outside your home, connects to your existing natural gas line or a dedicated propane tank, and provides automatic backup power within seconds of a utility outage. It's controlled by an Automatic Transfer Switch (ATS) wired between your main electrical panel and the utility meter. When the ATS detects an outage, it disconnects your home from the utility, signals the generator to start, and reconnects your home to generator power once it's stable. When utility power returns, the ATS reverses the process and shuts the generator down.
This is fundamentally different from a portable generator. A portable runs on gasoline (which goes bad in storage and is increasingly hard to acquire during emergencies), requires manual setup with extension cords or an inlet box, can't safely power critical home circuits without a transfer switch, and produces dangerous carbon monoxide if used indoors. A standby is professionally installed, professionally permitted, automatic, and is treated by code as part of the home's permanent electrical system.
The case for a standby has changed dramatically in Marin over the last five years. PSPS events — PG&E's Public Safety Power Shutoffs during high fire risk — have become routine in the late summer and fall, and multi-day outages are now an expected scenario for most of the county. Add the atmospheric river events that knock out transformers across the North Bay in winter, and a typical Marin household experiences multiple multi-hour outages per year and at least one multi-day outage every couple of years. For homes with medical equipment, work-from-home setups, food storage, or simply a strong preference for not living without power, a standby has shifted from luxury to durable infrastructure.
Definition
A residential standby generator is a permanently-installed backup power system, fuel-connected to natural gas or propane, controlled by an Automatic Transfer Switch (ATS), and sized to power either the whole home or a designated set of critical circuits during a utility outage.
Standby vs portable — why the choice is binary.
A portable generator is a tool you operate. A standby is infrastructure that operates itself. For Marin homes with multi-day PSPS exposure, a portable is an emergency stopgap; a standby is the right long-term answer. They serve different problems and shouldn't be confused.
Why sizing dominates every other decision.
An undersized generator that says 'whole-home' on the box but can't actually start a heat pump under load is the most common bad outcome in this whole category. Correct sizing — done by a C-10 against your actual measured loads, with inrush current accounted for — is non-negotiable.
Backup generators are deceptively simple — pick a kilowatt rating, hook up gas, done — and that simplicity hides a lot of decisions that matter for years. This pillar is the hub for everything: sizing, brand selection, transfer-switch logic, fuel choices, PSPS-readiness, and the install process. The deep guides below cover the cornerstone topics.
02Sizing — the decision that determines whether it works.
Generator sizing is not 'pick the biggest one you can afford.' It's a real engineering calculation against your specific loads, your inrush current (the startup surge from motors and compressors), and the way you actually use the home during an outage. Get it wrong and you have a generator that surge-trips when the AC kicks in; get it right and you forget you have one.
Here's how the sizing tiers map to real Marin homes.
14 kW — Essential circuits only
Fridge, lighting, internet, a few outlets, a small HVAC zone. Fits homes that want power continuity for medical equipment or food storage but accept some manual switching. ~$5,500–$8,500 installed.
18 kW — Most single-family homes, single AC/heat pump
Whole-home with one HVAC running at a time, normal kitchen loads, and EV charging at reduced amperage. ~$8,000–$12,000 installed.
22 kW — Larger homes, multiple HVAC zones, full EV charging
Two zones of HVAC simultaneously, well pump, hot tub, full EV charging during outage. Most common scope on Marin custom homes built since 2010. ~$11,500–$15,500 installed.
All HVAC zones simultaneously, full EV charging, electric range, water heater. Estate-class wiring with potential for a sub-panel architecture. ~$14,500–$19,500 installed.
We size against your specific loads — not a guess from a square-footage table.
Generator installation is a 3-to-6-week project from first call to first start. The on-site labor is concentrated in a 2-to-3-day window, but the calendar time is dominated by permit issuance, gas-utility coordination, and the pad cure (if poured). Here's the realistic picture.
The Problem
Homeowner experiences a multi-day PSPS event, decides 'never again,' and starts calling around. They get wildly different quotes — $6,500 from one installer, $14,200 from another — for what they think is the same job. The variance is mostly: pad work scope, ATS sizing, gas-line distance, and whether the quote includes the AHJ permit at all.
The Solution
We come out, measure the actual loads (sometimes with a clip-on amp meter on critical circuits to capture peak draw), check the gas service capacity and pressure, walk the pad location for setbacks (NEC and local fire-code clearances from windows, eaves, and combustibles), and produce an itemized estimate. The size, brand, ATS type, pad scope, gas-line scope, and permit are all listed separately. No surprise change orders.
The Resolution
Install runs 2-3 days on-site (pad prep day, set-and-connect day, commissioning day) over a 3-5 week elapsed timeline driven by permits and gas coordination. The generator is set, the ATS is installed in line with the meter, the gas line is run and pressure-tested, the AHJ inspects, the unit is commissioned with a manufacturer-witnessed first-start, and we walk the homeowner through the monitoring app. From here it self-tests weekly without you doing anything.
04Natural gas vs propane — the fuel decision.
For most Marin homes with existing natural gas service, NG is the right answer — no tank, no refills, no run-time limit. For homes without gas service (most of West Marin, parts of Sonoma corridor, some hillside Tiburon and Belvedere properties), propane is the answer and the tank sizing becomes a key consideration. The right choice depends on what the home already has and how you think about supply during multi-day events.
Natural gas — when it's available
Connect to existing PG&E natural gas service via a dedicated regulator. Unlimited runtime as long as gas keeps flowing (which during PSPS-type events, it generally does — PG&E's gas system is independent of the electrical grid). Lower per-hour fuel cost. No tank visual or footprint.
Propane — when NG isn't available, or for runtime certainty
Dedicated propane tank, typically 250-500 gallons buried or above-ground (subject to local fire-code setbacks). Independent of utility infrastructure (which can matter in severe events). Tank sizing should target 7-10 days of expected runtime at peak load.
05A realistic 30-60-90 from quote to commissioning.
Generator projects run longer than EV installs and shorter than full panel upgrades. The dominant variables are permit timing and (for new propane installs) tank delivery. Here's the typical breakdown.
Days 1–30
Site walk, sizing, permits
Load measurement on-site, written estimate, deposit, AHJ permit application filed, gas-utility ticket opened (PG&E for NG; propane company for tank install if needed).
Days 31–60
Pad work and gas coordination
Pad set or cured if poured (typically a composite pad or 4-inch concrete with rebar), gas-line stub installed, propane tank installed and filled if applicable. Materials staged.
Generator delivered and set on pad, ATS installed in line with main panel, gas connected and pressure-tested, electrical connections terminated, AHJ inspection, manufacturer-witnessed first-start, homeowner walkthrough.
06Brand comparison — Generac vs Kohler vs Cummins.
Three brands dominate the Marin residential standby market: Generac (largest market share, broadest dealer network), Kohler (premium build quality, often spec'd by builders), and Cummins (commercial-grade reliability in residential form factor). They're all good. The choice is about specific trade-offs.
Brand
Best for
Strengths
Considerations
Generac
Most Marin homes; broad sizing range
Largest dealer/service network in the Bay Area, broadest parts availability, strong monitoring app (Mobile Link), best price-to-capability for typical residential
Some homeowners feel the build is slightly less refined than premium brands
Kohler
Builder-spec'd homes; premium quality preference
Excellent build quality, quieter operation at idle, longer-stroke engine generally lower wear over time
Higher upfront cost; service network smaller than Generac
Cummins (Onan / RS-series)
Estate-class; runtime-critical applications
Commercial-grade engines in residential package, exceptional durability, best for very long runtime scenarios
Highest cost; service network limited in Marin (most service through Sacramento/Sonoma dealers)
Briggs & Stratton / Champion
Cost-sensitive smaller installs
Lower entry-level cost
Smaller dealer networks, lower long-term parts availability — we generally recommend the three above instead
07Maintenance — what you actually have to do.
Standby generators are designed to be set-and-forget, but 'forget' means 'we maintain them on a schedule,' not 'nobody ever looks at them.' Here's the realistic maintenance cadence and what we recommend.
Annual service — required for warranty
Oil and filter change, spark plug check, air filter inspection, battery test, full load-bank test, monitoring system verification. Typically $350-$550 per visit. We offer annual maintenance contracts that cover all manufacturer warranty requirements.
Weekly self-test — automatic
All major brands self-test once per week for 5-15 minutes (you choose the time). The unit runs, the controller verifies all systems, and any fault gets logged. With cellular monitoring, you get notified of any issue in near-real-time. We recommend the monitoring add-on on every install — it's the difference between knowing your generator works and assuming it does.
08Choosing a generator installer — the questions to ask.
Generator installation crosses three trades (electrical, gas, sometimes concrete) and three permitting authorities (AHJ electrical, AHJ gas if separate, sometimes county fire). The contractor coordinating all of that needs to be the C-10 of record. Here's what to verify.
Are they a factory-authorized installer for the brand?
Generac, Kohler, and Cummins all certify installers and dealers. Factory-authorized installers can register the warranty correctly, source parts faster, and access manufacturer technical support. We're a factory-authorized installer for the major residential brands.
Who pulls each permit?
Electrical permit is the C-10's job. Gas permit (if separate from electrical) varies by jurisdiction — sometimes it's pulled by the gas company; sometimes by the contractor. Fire code review for propane tank setbacks is another permit in some Marin AHJs. The right contractor has all of these mapped from day one.
Frequently Asked Questions
What size generator do I actually need for my Marin home?
Sizing is the most consequential decision in a generator project and the most commonly miscalculated. The right answer is determined by a real load analysis against your specific home — not a square-footage table. We measure peak load on critical circuits, account for inrush current from motors (HVAC compressors, well pumps, refrigerator compressors), and add the simultaneity factor based on how you actually use the home during an outage. For most Marin single-family homes with one HVAC system and standard kitchen/laundry loads, an 18-kilowatt generator is appropriate. Larger homes with two HVAC zones, EV charging, or a well pump typically need 22 kilowatts. Estate-class or all-electric homes with multiple zones and multi-EV households often need 26 kilowatts. Going under-sized is the worst common mistake: an undersized generator surge-trips on real loads and gives the homeowner the worst-of-both-worlds outcome. We size honestly — if you need 22 kW, we tell you 22 kW, and we show you the math.
How much does a whole-home standby generator installation cost in Marin?
All-in installed cost for a residential standby generator in Marin in 2026 ranges from $5,500 for a 14-kilowatt essentials-only setup to $19,500 for a 26-kilowatt estate-class install. The most common scope — an 18-to-22-kilowatt whole-home install with automatic transfer switch and natural-gas hookup — typically lands between $9,500 and $14,500 installed. That price includes the generator unit, the pad (composite or poured), the gas line, the automatic transfer switch, the electrical work to integrate with the main panel, the AHJ permits, the gas-utility coordination, the inspector visit, and the manufacturer-witnessed first-start. Propane installs run $2,500-$5,000 higher because of the tank, the trench, and the fire-code setbacks. Variables that move the price within those ranges: gas-line distance from meter to generator location, pad complexity, ATS type (service-rated vs non-service-rated), and any sub-panel work needed to consolidate critical circuits. We quote each scope specifically — no flat-rate estimators.
How long does a standby generator install take, start to finish?
From first call to first start, expect 3 to 6 weeks. The on-site work is concentrated in a 2-to-3-day window (pad day, set-and-connect day, commissioning and inspection day). The calendar time is dominated by permit issuance from your AHJ (typically 5-10 business days for residential generator permits in Marin), PG&E or propane-company coordination for the gas side, and — if the pad needs to be poured — the concrete cure window (typically 5-7 days minimum). For propane installs, tank delivery from the supplier can add 1-2 weeks. We schedule the calendar work from the moment we have a signed estimate, so the permitting and pad work happen in parallel with the equipment order. For PSPS-driven urgent installs in dry season, we sometimes accelerate by working with propane companies on expedited tank delivery and AHJs on permit prioritization — but no contractor can compress the gas-pressure-test or AHJ-inspection windows below what they actually require.
Do I need a permit for a residential backup generator in Marin?
Yes, in all Marin jurisdictions, for every residential standby generator installation. The permit is pulled with the AHJ for the electrical work, and a separate permit or fire-code review may apply for the gas-line work and (for propane) the tank setback. The fees are itemized on our estimate. We pull every permit in-house; homeowners don't fill out forms. After installation, the inspector visits to verify the electrical work (ATS wiring, grounding, panel labeling), the gas-line installation (pressure-tested and code-compliant), and the unit setbacks from windows, eaves, vents, and combustibles per local fire code. The permit becomes part of the home's permanent record, which matters at resale and for insurance verification. Some Marin AHJs additionally require county fire-marshal review for propane tank installs above certain sizes; we handle that coordination as part of the project.
Will my generator work during a PSPS event?
Yes, and this is one of the most important questions homeowners ask. A properly-installed standby generator is fully independent of the utility electrical grid — it starts and runs without PG&E, and the Automatic Transfer Switch keeps your home safely isolated from the grid for the duration of the outage. For natural gas units, the question becomes whether the gas supply stays available during the event. In Marin, PG&E's natural gas distribution system is generally independent of the electrical grid and remains pressurized during typical PSPS events. However, in severe wildfire conditions, gas service can be intentionally shut down in specific areas as a safety measure. For homes where this is a concern — generally hillside and rural properties — propane is the more PSPS-resilient choice because the fuel supply is on-site in your tank. We help every homeowner think through this trade-off based on their specific neighborhood's PSPS and gas-shutoff history, and we recommend propane tank sizing that targets 7-10 days of runtime at peak load.
Natural gas or propane — which should I choose?
If your home already has natural gas service, NG is usually the right answer. You're already paying for the gas line, the supply is continuous, you don't need a tank, and the per-hour fuel cost is lower than propane. The exception is when PSPS-or-fire gas shutoff risk is meaningful for your specific location — hillside, rural, or fire-prone — in which case propane provides supply independence. If your home doesn't have natural gas service (most West Marin, parts of the Sonoma corridor, some hillside Tiburon and Belvedere properties), propane is your only option and the question becomes tank sizing. We recommend tanks sized for 7-10 days of runtime at expected peak load, which for most Marin homes means a 500-gallon tank (above-ground or buried). The tank cost varies based on size and whether it's buried, and there are fire-code setback requirements from your home, neighboring properties, and ignition sources that affect placement. We walk every property in person for propane installs to confirm tank placement before quoting.
What's the difference between automatic and manual transfer switches?
An Automatic Transfer Switch (ATS) is the brain of a standby generator system — it monitors utility power continuously, signals the generator to start within seconds of an outage, and transfers your home from utility to generator power without you doing anything. When utility power returns and stabilizes, it transfers back and shuts down the generator. A Manual Transfer Switch (MTS) requires a homeowner to flip the switch themselves to engage generator power, which means standby generators with MTSs only work if you're home and awake during the outage. For whole-home backup, an ATS is almost always the right answer. MTSs are appropriate in two narrow scenarios: portable-generator setups (where you connect the generator manually), and certain commercial installations where the customer specifically wants a human in the loop. ATSs add $400-$1,500 to the installed cost depending on amperage and whether they're service-rated, but for the use case — automatic backup during PSPS or storm events when you may not be home or awake — the value is dramatic. We default to ATS on every residential install unless a homeowner specifically requests otherwise.
What maintenance does a standby generator require?
Standby generators require regular maintenance to stay reliable and to keep their factory warranty valid. The annual service visit — typically $350-$550 — includes oil and filter change, spark plug check, air filter inspection, battery test, full load-bank test (running the unit at rated load to verify all systems perform under stress), and verification of the monitoring system. Beyond the annual, the unit self-tests weekly for 5-15 minutes (the test time is configurable). Every major brand has a recommended maintenance interval that you must meet to maintain the warranty: Generac is generally 200 hours of runtime or annually (whichever comes first), Kohler is similar, Cummins is sometimes longer. We offer annual maintenance contracts that include the scheduled service plus priority dispatch if anything goes wrong, which we recommend on every install. The biggest mistake homeowners make is buying a generator and never maintaining it — at year 5 it doesn't start during the PSPS event, and the post-mortem usually shows the maintenance was skipped.
Can my generator power an EV charger during an outage?
Yes, but the sizing math gets specific. An EV charger pulls 32 amps continuous at 240 volts, which is about 7.7 kilowatts of continuous load — meaningful for a generator that's also running HVAC, refrigerator, lights, and well pump. For a typical 18-kilowatt generator on a typical Marin home, you can charge an EV during an outage if you reduce charger amperage (most modern chargers support throttling — set to 16A or 24A continuous instead of 32A). For 22kW or 26kW generators, full-amperage EV charging is feasible alongside the rest of the home. We do this load analysis as part of every sizing conversation when EV charging is on the home — it changes the answer. For two-EV households or estate-class homes, we sometimes recommend smart load management that throttles the EV chargers automatically when the generator is the power source. This is one of the reasons we run a real load calc with you, not just a square-footage estimator.
How do I find a qualified generator installer in Marin?
Three things to verify before signing any quote. First: California C-10 electrical contractor license — the same baseline that applies to any residential electrical work. Verify the license number on the CSLB lookup, confirm it's active, and check that there's no recent disciplinary history. Generator-specific HVAC or gas-fitter licenses may also apply depending on the scope; the C-10 should coordinate those if required. Second: factory-authorized status for the brand you're considering. Generac, Kohler, and Cummins all certify dealers and installers; an authorized installer can register the warranty correctly, source parts faster, and access manufacturer technical support that non-authorized installers can't. Third: real installation experience in Marin specifically. Generator installs are AHJ-dependent and PG&E-dependent; a contractor who's done 50 installs in San Diego doesn't have the Marin AHJ relationships or the PG&E coordination experience you want. Towery Electric is C-10 #989290, factory-authorized for major residential brands, and has completed 150+ standby generator installs across Marin since 2014.
How We Reviewed This Page
All cost ranges reflect actual 2026 Towery Electric quote data from Marin County standby generator installs — not industry-average estimators.
Sizing recommendations reference NEC Article 702 (Optional Standby Systems), Generac/Kohler/Cummins manufacturer sizing guidance, and the load calculation methodology in NEC Article 220.
PSPS-readiness guidance draws from PG&E's published PSPS history for Marin County, current as of mid-2026.
Fuel and runtime calculations use manufacturer datasheets for the 14, 18, 22, and 26 kW units across the three major residential brands.
Technical review by Alex Towery, founder and C-10 #989290 holder, with 150+ standby generator installs completed in Marin since 2014.
Permit and inspection process reflects current AHJ practice in Novato, San Rafael, Mill Valley, and unincorporated Marin County as of mid-2026.
This guide reflects Towery Electric's professional standards as a California-licensed C-10 electrical contractor and is for general information. Site conditions, panel configurations, code amendments, and permit-authority requirements vary; final scoping, sizing, and code compliance for your specific address are determined on a paid site assessment. We follow California Electrical Code (Title 24, Part 3) and applicable NFPA 70 (NEC) editions adopted by your AHJ.
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