A single Tesla Powerwall stores 13.5 kWh of energy. That's enough to keep the lights on and the refrigerator running in a typical home for several hours during an outage. But for large residential properties — the kind with guest houses, pool equipment, wine cellars, EV chargers, home offices, security systems, and landscape lighting — a single battery doesn't come close to covering the load. And stacking three or four batteries without rethinking the system architecture creates its own set of problems.
This is where estate microgrids come in. Rather than bolting batteries onto a conventional residential electrical system, a microgrid is a fundamentally different approach to powering a property — one that treats the entire estate as an integrated energy system.
What makes an estate a microgrid candidate
Not every large home needs a microgrid. But certain characteristics make a property a strong candidate:
- Multiple structures: A main house, guest house, ADU, pool house, or detached garage each with its own electrical sub-panel.
- High critical loads: Wine storage, medical equipment, home offices that generate income, security systems, and water pumps that can't tolerate extended outages.
- Large electrical loads: Pools, spas, EV chargers (especially multiple Level 2 or DC fast chargers), and commercial-grade HVAC systems.
- Remote or fire-prone locations: Properties in Marin County, Napa Valley, the East Bay hills, or other areas where PG&E's Public Safety Power Shutoff (PSPS) events can mean multi-day outages.
- New construction or major renovation: The best time to design a microgrid is before the walls go up, when conduit runs, panel placement, and load distribution can be optimized from the start.
How an estate microgrid differs from stacked batteries
The simplest approach to residential energy storage is adding one or more batteries behind your main electrical panel, with a transfer switch that disconnects from the grid during outages. That works fine for modest loads. But for large properties, this approach has significant limitations.
The stacking problem
Simply adding more batteries doesn't solve the fundamental challenge of a large estate. A 200-amp main panel feeding a main house, a sub-panel feeding a guest house, and another sub-panel feeding pool equipment all need coordinated management. Stacked batteries behind one panel can't intelligently manage loads across multiple structures or prioritize critical circuits during extended outages.
An estate microgrid addresses these limitations through integrated design. Rather than adding storage as an afterthought, the microgrid controller manages the entire property's energy flow — solar generation, battery storage, grid connection, and load distribution — as a single coordinated system. Key differences include:
- Centralized intelligence: A microgrid controller monitors and manages energy flow across all structures and circuits, making real-time decisions about generation, storage, and load management.
- Load prioritization: During extended outages, the system automatically sheds non-critical loads (landscape lighting, pool heating) to extend runtime for critical loads (security, refrigeration, home office, medical equipment).
- Distributed generation: Solar arrays can be placed on multiple roof surfaces or ground-mounted locations, with production aggregated and managed centrally.
- Seamless islanding: The transition from grid-connected to island mode (and back) happens automatically and virtually instantaneously — no flickering, no rebooting, no manual intervention.
Designing for real-world scenarios
The most important phase of an estate microgrid project is the design phase. We work through a series of scenarios with each client to ensure the system performs when it matters most:
Scenario 1: Short outage (2–4 hours). The most common grid disruption. The microgrid maintains full property operation with no load shedding, using battery reserves supplemented by solar production.
Scenario 2: Extended PSPS event (24–72 hours). This is the scenario that drives most estate microgrid projects in Northern California. The system prioritizes critical loads, manages battery charge cycles with available solar, and can sustain essential operations for days.
Scenario 3: Daily optimization. Most of the time, the grid is available. During normal operation, the microgrid optimizes energy costs by maximizing solar self-consumption, managing time-of-use rates, and minimizing grid dependence — reducing monthly utility bills significantly.
Scenario 4: EV charging integration. With many estate properties now housing two or three EVs, charging management becomes critical. The microgrid coordinates EV charging with solar production, battery state-of-charge, and grid rates to avoid demand spikes and minimize charging costs.
What a typical estate microgrid looks like
Every property is different, but a representative estate microgrid for a large Marin County or Napa Valley property might include:
- 15–30 kW of solar across multiple roof surfaces or a ground-mount array
- 40–80 kWh of battery storage (multiple units, potentially distributed across structures)
- A microgrid controller with automated islanding and load management
- Integrated EV charging management for 2–3 vehicles
- A monitoring dashboard accessible from any device, showing real-time generation, consumption, storage state, and grid status
Total installed cost for a system of this scale typically ranges from $80,000 to $200,000 before incentives, depending on the property's complexity and the specific equipment selected. The federal Investment Tax Credit (30%), California's SGIP rebate, and ongoing utility savings often reduce the effective cost by 40 to 60 percent.
Working with your architect and builder
For new construction and major renovation projects, we collaborate directly with your architect and general contractor to integrate the microgrid into the project from the design phase. This coordination ensures optimal conduit routing, panel placement, equipment siting, and aesthetic integration — avoiding the compromises and added costs that come with retrofitting.
The properties where we see the best outcomes are the ones where we're brought in early — during schematic design, not after the drywall is up. Early involvement means better performance, cleaner installation, and lower total cost.
For existing properties, a microgrid retrofit is absolutely possible and often makes excellent sense, particularly for properties in PSPS zones. The design process starts with a comprehensive site assessment and load analysis to understand the property's energy profile and identify the optimal system configuration.
Getting started
If your property has the characteristics described above — multiple structures, high loads, fire-zone location, or simply a desire for energy independence — an estate microgrid consultation is the logical first step. We'll visit the property, review your electrical infrastructure and utility history, discuss your priorities, and develop a preliminary design and cost estimate.