Off-grid and Backup Power
Choose and size batteries, chargers, inverters and a UPS for a home that loses the grid, and prove the night and the outage with a test run.
Batteries and BMS, chargers, inverters, home UPS, brownouts, the off-grid template and its exam.
Before you start: House Wiring Basics or the first steps of Solar PV Systems
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Module 1: 1 · Cells, packs and internal resistance
Extra practice:
Module 2: 2 · Charging
Extra practice:
- Single 18650 charger with LED charge indicator
- Single 18650 charger with a 3-LED charge indicator (green 80–100 %, yellow 40–79 %, red below 40 %)
Module 3: 3 · Lead-acid against LiFePO4
- Lead-acid against LiFePO4: usable capacity, voltage and life
- Economics: payback, and what a battery really costs per kWh
Module 4: 4 · Building the bank
- 100 Ah 12 V LiFePO4 battery (4S17P, 32700 cells) with charger
- 200 Ah power station on a 12.8 V LiFePO4 battery: 2 × 12 V, 3 × USB, mains charger
Extra practice:
- 50 Ah 12 V LiFePO4 battery (4S9P, 32700 cells) with charger
- 200 Ah power station from four 3.2 V prismatic LiFePO4 cells: 4S BMS, 2 × 12 V, 3 × USB, mains charger
Module 5: 5 · Inverters and the home UPS
Extra practice:
- Home UPS on 8 × 3.2 V LiFePO4 cells + BMS: charger, inverter, changeover relays, two 220 V outputs
- Router DC UPS
Module 6: 6 · Living through a brownout
- Sari-sari store freezer through a brownout: battery, inverter and hours
- 1 HP inverter aircon on a 3.6 kW hybrid at night: what the battery sees
Extra practice:
- Why a 1.5 HP non-inverter aircon trips a 3 kW inverter at start-up
- Grid-tie solar in a brownout: why the lights go out even at noon
Module 7: 7 · Small off-grid systems
Extra practice: