Charging Through a Grid Failure: What February 2021 Changed
Backup power for Central Texas households after Uri — what a battery actually covers, when a generator is the honest answer, and where the car fits in.
By Austin EV Charger Installers
Nobody in Central Texas needs the case for backup power explained. February 2021 did that.
What is worth explaining is what each option actually delivers, because the honest answer varies quite a lot depending on where in this metro you live.
The question people ask, and the better one
The common question is whether you can charge the car during an outage.
Practically, no. Not from the grid, and not usefully from a home battery — a vehicle pack is far larger than a residential storage system, and pointing one at the other empties the house’s reserve for a modest amount of range. That is not what a home battery is for.
The more interesting question runs the other way: can the car supply the house?
For a growing number of vehicles, yes. A full-size electric truck carries a pack several times the capacity of a typical fixed home battery, and during an outage it is sitting in the driveway doing nothing. Bidirectional charging turns that into backup.
Two honest caveats. Support is model-specific rather than brand-specific, and it needs confirming against your actual vehicle rather than assumed. And the energy leaves when you drive, which is a real limitation during exactly the sort of regional event where you might also need to go somewhere.
What to back up, which is the whole design
This is where the money is decided, and it is the same conversation whether you choose a battery, a generator or the vehicle.
Whole-home backup means sizing the system against whatever the house might draw simultaneously. In a climate where the largest load is air conditioning and the highest-risk outages come with extreme weather, that is an expensive specification and most of the capacity sits idle most of the time.
A critical-loads subpanel is the alternative. You choose the circuits that genuinely have to survive — refrigeration, enough lighting to live by, outlets for devices and any medical equipment, networking, and usually one HVAC zone rather than the whole system. The system is sized against that list.
The result is smaller, cheaper, and runs considerably longer on the scenario you were actually worried about. The subpanel decision affects the final bill more than the choice of hardware does.
Battery or generator, by where you live
The deciding factor is runtime, and it splits this service area cleanly.
Inside the city and the closer suburbs — Austin, Round Rock, Pflugerville, Cedar Park — outages tend to be shorter. A well-designed battery covers them silently, needs no fuel, and requires nothing of you.
Out on the Hill Country acreage — Dripping Springs, Driftwood, Spicewood, Wimberley, Liberty Hill, Lago Vista — properties sit at the end of long distribution runs and restoration after a regional event takes longest. The failure mode being planned for is days rather than hours, and a generator runs as long as the fuel does.
There is a second factor out there that tips it further: well water. A great many rural properties draw from a well, which means losing power means losing water pressure. That changes the calculation materially, and the well pump has to be in the sizing rather than remembered afterwards.
For generators on the acreage, propane is usually the fuel since mains do not reach, and the tank needs sizing for a multi-day event rather than for a heating appliance.
Heat is a design constraint here
Batteries have an operating temperature range and cell life degrades faster at the top of it. A unit mounted where it takes direct afternoon sun through a Central Texas summer spends months in the least favourable part of that band.
So siting is a design decision on this job rather than a default: a shaded elevation, a garage interior, or conditioned space where the product allows it. It costs nothing to get right at installation and cannot be fixed cheaply later.
Interconnection, and six utilities
Anything that can operate alongside the grid needs your utility’s agreement about how it behaves — particularly that it separates properly during an outage so it cannot energise lines that crews believe are dead.
Six providers serve the cities on this site with six sets of requirements. Austin Energy, Georgetown and San Marcos are municipal; Pedernales and Bluebonnet are cooperatives; Oncor is a delivery utility. We establish which one serves your meter before quoting a timeline, because on these projects the approval usually sets the schedule rather than the installation.
Designing it alongside the charger
If you already have a charging circuit, or are planning one, design the two together against a single load calculation.
A charger, a battery, possibly solar and possibly a generator on one service is an integration problem. Solving it once at the start is substantially cheaper than solving it three times as each piece arrives.