Battery Storage and San Diego Power Outages

Why Outages Keep Happening Here

California's grid is under pressure from three directions at once, and San Diego County sits in the path of all three.

• Public Safety Power Shutoffs — in dry, windy conditions utilities de-energise lines to prevent ignition, taking whole neighbourhoods offline for planned periods.
• Heat-wave demand — extended high temperatures drive air-conditioning load to levels that strain generation and transmission.
• Ageing infrastructure — equipment installed for a smaller, less electrified demand profile.

SDG&E customers carry some of the highest electricity rates in the country while dealing with this. That combination — expensive power that is also not fully dependable — is the practical case for storage.

Solar Without a Battery Shuts Off During an Outage

This surprises most people, and it is worth being blunt about. A standard grid-tied solar array stops producing the moment the grid goes down.

It is a safety requirement, not a fault. If your system kept exporting into lines that utility crews believe are dead, it would put those crews at risk. The inverter is required to disconnect.

A battery with the right islanding equipment changes that. It separates your property from the grid and keeps your circuits running from stored energy, with the solar array able to recharge it through the day.

How It Works Across a Normal Day

• Daytime — the array powers the building and charges the battery with what is left over.
• Evening peak — the property draws from the battery instead of buying at the most expensive hours of the rate schedule.
• Overnight — the battery covers what it can; anything beyond that comes from the grid at off-peak rates.
• During an outage — the system disconnects from the grid and runs your designated circuits from storage, recharging from solar each day.

The second point is where a battery earns money in a normal month. Under time-of-use pricing the gap between peak and off-peak rates is what makes stored energy worth more than exported energy.

What a Battery Realistically Covers

Runtime is a function of how much capacity you install and what you ask it to carry. That is a design decision, not a product specification, and it is the first thing worth being honest about.

A system sized for essentials — refrigeration, lighting, networking, medical equipment, a few outlets — will run far longer than one asked to hold whole-building air conditioning through a heatwave.

For a commercial property the question is usually different again: not comfort, but which operations cannot stop. Refrigerated stock, servers, access control, life-safety systems. We size from that list rather than from square footage.

Where the Tax Position Stands in 2026

This changed significantly and a lot of material still online has not caught up.

Tax treatment depends on your circumstances and nothing here is tax advice. We design and install the system and work alongside your accountant on how the credit applies.

What We Look At Before Quoting

• Twelve months of SDG&E bills, to see your real consumption shape rather than an average.
• Your rate schedule, because peak-to-off-peak spread determines what stored energy is worth to you.
• The circuits that genuinely need to stay live, agreed with you rather than assumed.
• Main panel capacity and where the equipment can physically and safely go.
• Whether storage is best installed with the array or added later, which changes both cost and tax treatment.