Methodology → Battery Recharge Cost
How Battery Recharge Cost Is Estimated
This page explains how PriceOfElectricity.com estimates the electricity cost to recharge a home battery from the grid.
Overview
Recharge cost is estimated from battery capacity and the local electricity price. The site uses standard example battery sizes common for residential backup systems. Charging losses increase the total electricity required from the grid.
Formulas
Baseline cost (ignoring losses):
baselineRechargeCost = batteryCapacityKwh * rateDollarsPerKwh
With charging losses (typical round-trip efficiency ~90%):
rechargeCostWithLosses = (batteryCapacityKwh / 0.9) * rateDollarsPerKwh
The factor 0.9 approximates charging efficiency; actual efficiency varies by battery type and conditions.
Standard battery sizes
The site uses common residential backup battery capacities (e.g., 10 kWh, 13.5 kWh, 20 kWh) as examples. These are usable capacity values, not nameplate ratings.
Scope
This methodology estimates electricity cost only. It does not include battery purchase price, installation, maintenance, inverter losses, or degradation over time.