The inverter converts DC electricity from batteries into AC power used by most household devices. Correct inverter sizing is essential for stable operation and safe system performance.
Continuous watts vs surge watts
Inverters are rated in two important ways:
- Continuous power: The steady load the inverter can support.
- Surge power: Short bursts of higher output for motor startup or compressor loads.
Motors, refrigerators, pumps, and power tools often require higher startup power than their running watt rating.
Pure sine wave vs modified sine
- Pure sine wave: Smooth AC output, compatible with sensitive electronics and modern appliances.
- Modified sine wave: Lower cost, but not ideal for sensitive or inductive loads.
For most modern systems, pure sine wave inverters are preferred.
Efficiency and idle draw
Inverter efficiency determines how much battery energy is converted into usable AC power. Even when no loads are connected, inverters consume a small amount of power (idle draw), which affects overall system runtime.
System voltage
Inverters are built for specific DC input voltages (12V, 24V, 48V). System voltage selection influences wiring size, efficiency, and scalability. Higher voltages generally reduce current and wiring losses in larger systems.
Planning inverter size
To select the correct inverter:
- Calculate total continuous load in watts.
- Identify highest surge loads.
- Confirm battery discharge capability.
- Review complete load calculations in solar system sizing.
Battery capacity must support inverter demand. See solar batteries and storage for storage fundamentals.