Battery SOC Stuck at 100% But House Still Pulls From Grid

Why this matters

A homeowner who paid for storage expects the battery to power the house, so a battery sitting at 100 percent state of charge while the meter keeps importing grid energy reads as a broken battery. It usually is not. The battery is full and healthy; the issue is in how the system is configured to DISCHARGE it - operating mode, reserve settings, CT sensing, or a power limit. Replacing or RMAing a full, working battery for this is a costly miss. This tree walks the discharge logic from mode to metering to power limits and finds why a charged battery is not feeding the home.

Symptom presentation

The battery app or gateway shows SOC pinned at 100 percent (or at the customer's set reserve) and not discharging, while the utility meter or home-energy monitor shows the house importing from the grid at the same time - lights, HVAC, and loads running on grid power despite a full battery. The customer reports "the battery is full but I'm still buying electricity." This often appears right after commissioning or after a settings/firmware change.

Quick checks

Read the battery operating mode and reserve first in the app (Tesla Powerwall, Enphase IQ Battery, or the inverter's storage settings):

• Mode is Backup-Only (or "backup reserve" at 100 percent): the battery is intentionally holding full charge for outage backup and will NOT discharge into normal loads by design. That is the configured behavior, not a fault. Change to Self-Consumption/Self-Powered if the customer wants daily cycling.
• Mode is Self-Consumption but battery still will not discharge: continue to the CT/metering and power-limit branches.
• Backup reserve set to 100 percent in any mode: the system treats the whole pack as reserve and never discharges. Lower the reserve to the customer's desired backup floor.

Then confirm the home-load CTs/metering are reading actual house consumption, because the battery only discharges when it SEES a load to serve.

Isolation tree

Branch A - Operating mode / reserve (the usual cause). Backup-Only mode or a 100 percent backup reserve keeps the battery full on purpose. Confirm the mode and reserve in the app. Self-Consumption (Tesla) / Self-Powered / Self-Consumption (Enphase) with a low reserve is the mode that discharges into household loads. Remedy: set the intended mode and a sensible reserve (e.g., a 20 percent backup floor) per the customer's priority of daily savings versus outage protection.

Branch B - CT / consumption metering fault. The battery system decides when to discharge based on what its CTs report the house is consuming. If a home/consumption CT is reversed, on the wrong conductor, unplugged, or reading zero, the system thinks there is no load to serve and stays idle while the grid actually feeds the house. Confirm: the app's home-consumption reading is implausibly low or zero while loads clearly run, or it reads negative. Remedy: correct CT orientation/phase/seating per the manufacturer and re-commission so consumption reads true.

Branch C - Time-based control / utility schedule. Time-of-use or a utility export/charge schedule (or a VPP/grid-services program) may be holding the battery full to discharge during a later peak window, or charging it to 100 percent on a schedule. Confirm: the app shows a TOU/advanced schedule or program enrollment governing discharge timing. Remedy: adjust the schedule to the customer's intent, or explain the deliberate peak-shift behavior.

Branch D - Power / current limit reached. The battery's continuous power rating may be below the instantaneous house demand (e.g., HVAC compressor inrush, EV charger, electric range), so it supplies what it can and the grid covers the remainder, while a brief full-SOC reading persists. Confirm: import occurs mainly during high-power loads and the battery IS contributing up to its rating. Remedy: this is a capacity limit, not a fault; size expectations to the pack's continuous kW, or add capacity.

Branch E - Grid-tie/islanding configuration or fault. A storage system that has not fully commissioned its grid profile, or that is in a fault/standby state, may sit charged but inert. Confirm: gateway/system status shows a fault, not-commissioned, or standby state rather than normal operation. Remedy: complete commissioning, clear the fault, and verify the system is in normal grid-tied operation.

Confirming diagnosis

The deciding read is operating mode + reserve + consumption-CT reading together. Backup-Only or 100 percent reserve fully explains a non-discharging full battery (Branch A) - set it to Self-Consumption with a lower reserve and confirm it begins serving load. If the mode is already correct, a zero/negative home-consumption reading in the app while loads run confirms a CT fault (Branch B). If consumption reads correctly and the battery DOES discharge but the grid still covers high-power moments, that is a power-limit reality (Branch D), not a defect. A system status of fault/standby points to commissioning (Branch E). The battery's own SOC and health screens confirm the pack itself is fine - a full, healthy pack is the premise of this whole tree.

Remediation

Set the operating mode to the customer's intent (Self-Consumption/Self-Powered for daily cycling) with a backup reserve floor that matches their outage tolerance. Correct any reversed or mis-clamped consumption CT and re-commission the metering so the system sees true household load. Tune TOU/program schedules to the desired behavior or explain deliberate peak-shifting. Set expectations against the pack's continuous power rating for large instantaneous loads, and add capacity if the customer needs it. Complete commissioning and clear any standby/fault state. After changes, watch a real evening: the battery should discharge into household loads and the grid import should drop accordingly until the reserve floor is reached.

References

• NEC Article 706 - Energy Storage Systems (battery system configuration and disconnect context).
• NEC Article 705 - Interconnected Electric Power Production Sources (storage interconnection, metering).
• Tesla Powerwall and Enphase IQ Battery operating-mode documentation (Self-Consumption/Self-Powered vs Backup-Only, backup reserve, CT/metering commissioning).
• UL 9540 - Energy Storage Systems and Equipment, and IEEE 1547 (grid-interactive storage operation and commissioning).