SMA BU-STRT-US-50 Transfer Switch

SMA BU Transfer Backup Start Module for Manual Backup

SMA BU Transfer supports SMA Backup Secure operation during a grid outage. It enables manual backup power from a Sunny Boy inverter. This module supports a 120Vac backup outlet circuit. It can deliver up to 1.9kW when conditions allow. The installer must provide a separate switch and outlet.

Product Features

This backup start module is designed for select SMA inverters and supports the Backup Secure feature. Previously labeled as SPS, it helps provide limited daytime power during outages. Intended for a dedicated backup receptacle circuit, it is not a whole-home backup system. It does not include an automatic transfer switch, nor does it energize a main service panel. The device is designed for manual activation by a user and requires correct wiring by a qualified installer.

Key terms associated with this product include inverter accessory, manual transfer, PV system, grid-tied solar, and Backup Secure. These terms reflect the typical use case and common electrical planning needs. Always verify local code requirements before installation to ensure compliance.

This solution simplifies a basic emergency power setup. It operates with properly configured solar inverters and supports a separated load circuit. This reduces confusion during an outage and supports clear labeling for safer use. Safety heavily depends on a correct system design. A lockable disconnect may be required. The dedicated outlet must be identified solely as backup power. Overcurrent protection should be sized correctly, and grounding must follow the NEC and local rules.

How SMA BU Transfer Works

The module works with compatible SMA inverter firmware, enabling an isolated backup outlet circuit. This outlet is used only during an outage. It is not intended for exporting power and supports limited essential loads only. During normal grid operation, the system operates as grid-tied solar. When the grid fails, the inverter stops exporting power, and the user initiates manual backup mode. This module supports that manual start function and allows the inverter to energize the dedicated outlet circuit.

The available backup power depends on sunlight and PV production. Output is limited to about 1.9kW at 120Vac. Motor loads may surge above this limit. Sensitive electronics should use proper power supplies. Users should avoid overload conditions to maintain safe operation.

The device does not include energy storage and does not provide nighttime power without batteries. It is intended for daytime, sun-dependent use only. For longer backup, consider additional storage solutions and confirm compatibility before specifying equipment. Use clear operating instructions and keep the backup outlet accessible. Label the outlet as Backup Secure power. Keep cords and adapters rated for the load and avoid backfeeding premises wiring from the outlet.

Applications of the SMA BU Transfer Module

This backup start module is commonly used in residential PV systems that require minimal backup power. It supports essential loads such as phone charging and internet equipment. It also handles small fans or lights but is not designed for electric heating loads. In light commercial PV sites, it supports critical plug loads like network switches and small office devices. It can also power security equipment. Load selection must always remain within the 1.9kW limit to ensure safe operation.

The product is useful where a full transfer switch is not planned. It supports a simple backup outlet strategy, reducing project complexity. This can lead to fewer added equipment needs but still requires careful design and inspection. Common planning considerations include circuit routing and labeling, confirming a suitable location near the inverter, conduit and conductor sizing, required protection devices, and ensuring the installer provides the switch and outlet components.

For related products, visit the Portlandia Electric Supply collection. This internal resource is helpful for selection support. Solar and inverter accessories collection.

For additional research, review public resources and model references. Use this search to find third-party listings. Google search for SMA BU-STRT-US-50.

Specifications of SMA BU Transfer

Specifications of SMA BU Transfer below reflect available product data. No datasheet was provided for this request. Dimensions and weight are not confirmed. Verify details before ordering or installing. Always confirm compatibility with the target inverter model.

Installation of SMA BU Transfer must be performed by qualified personnel. Follow NEC requirements and local amendments. Confirm conductor ratings and enclosure requirements. Verify grounding and bonding methods, and test operation with the specific inverter model before use.

This backup solution is ideal for essential, low-power plug loads. Keep loads simple and well-documented. Avoid multi-outlet power strips whenever possible. Use only listed cords and connectors. Turn off loads before changing operating modes for safety.

This module provides a practical backup outlet option. It supports basic resilience during daytime outages. The system remains dependent on PV availability and is not a substitute for batteries. It should be specified with accurate site expectations for reliable performance.