Efficiency formula
AC output = DC input × (efficiency ÷ 100). Loss watts = DC − AC. Size batteries for DC input including losses.
Sizing tip
When sizing backup, divide load watts by efficiency before converting to Ah. Pair with Home Backup Sizing for bank capacity.
Frequently asked questions
Q: Why is efficiency below 100%? A: Switching losses and heat in the inverter. Q: Does efficiency change with load? A: Yes—often lowest at very light load.