Common-area backup paid for by resident batteries

The starting point

• Common-area electricity was the association's fastest-growing expense with no lever to control it.
• A diesel generator covered only the fire pump and one elevator, and failed its last two load tests.
• Residents were installing chargers ad hoc, threatening garage service capacity.

The build

1. Phase 1

   Garage subpanel rebuild

   Ad hoc charger runs were replaced with a managed subpanel so every bay shares capacity instead of racing for it.

2. Phase 2

   Owner opt-in terms

   Residents set a reserve floor and receive a monthly common-charge credit for capacity made available to the association.

3. Phase 3

   Common-area dispatch

   Aggregated capacity is dispatched against house-meter peaks before any export, cutting demand charges on both services.

4. Phase 4

   Backup mode

   Elevators, fire pump, hallway lighting and dock power transfer to stored capacity automatically when the grid drops.

Results

Measured outcomes

Measured against a twelve-month pre-V2G baseline at Lighthouse Point Residences.

Key project metrics

Annual value

$29,900 avoided demand charges plus retired generator service

Capital required

$0 special assessment — funded from reserve offset

Payback

21 months against reserve contributions

Time to value

16 weeks including garage subpanel rebuild

"The generator only ever covered the minimum. Resident batteries now carry the elevators and the hallways, and the board's power bill went down doing it."