A C-46 contractor is preparing an estimate for a residential PV system. The client has specifically requested a system that can provide partial power during grid outages without relying on batteries. Which of the following inverter types would be MOST suitable for this requirement?
- AMicroinverter
- BGrid-tied inverter with secure power supply (SPS) or PV-direct backup
- COff-grid inverter
- DStandard grid-tied (string) inverter
Show answer & explanationAnswer & explanation
Correct answer: B. Grid-tied inverter with secure power supply (SPS) or PV-direct backup
A standard grid-tied inverter shuts down during grid outages. An off-grid inverter requires batteries. Microinverters, while grid-tied, also shut down during outages. A grid-tied inverter with secure power supply (SPS) or PV-direct backup is specifically designed to provide a limited amount of AC power directly from the PV array during a grid outage, even without batteries, making it the most suitable option.
Why the other options are wrong
- A. Microinverters are grid-tied and also shut down during grid outages (anti-islanding).
- C. Off-grid inverters require a battery bank to function and provide power during outages.
- D. Standard grid-tied inverters are designed to shut down during grid outages for safety (anti-islanding).
Secure Power Supply (SPS) Inverter
A Secure Power Supply (SPS) or PV-direct backup feature in a grid-tied inverter allows for a dedicated outlet to provide limited, non-battery-backed AC power directly from the PV array during a grid outage, as long as the sun is shining.
- Provides emergency power during grid outages without batteries.
- Power is available only when the sun is shining.
- Typically limited to a single dedicated outlet or small load center.
- Does not provide whole-home backup.
Memory trick: Solar Power During Shutdowns? Secure Power Supply is the Smart Solution.