Active diode reduces photovoltaic junction box temperature by 50 degrees C

Texas Instruments Inc. has introduced a smart bypass diode in a standard surface-mount package with 15-A current handling capability and what it claims offers the industry’s lowest power dissipation.

In a typical application, each SM74611 lowers power dissipation by 80 percent and reduces the operating temperature inside the junction box by 50 degrees C when compared with a similar box using three conventional Schottky diodes, according to TI.

When a photovoltaic (PV) solar panel is shaded, the SM74611 active diode provides an alternate low-resistance path for string current to prevent hot spots that can damage the panel. The SM74611 protects the panel and improves PV solar panel reliability by boosting efficiency, and the reduced thermal dissipation enables more compact junction boxes with smaller heat-sinks.

Key highlights:

• 80-percent lower power dissipation than Schottky diodes reduces ambient temperature inside the junction box by 50 degrees C, improving the current rating of existing junction boxes, as well as enabling smaller boxes with improved current rating.
• Current handling up to 15 A with no avalanche effect.
• Reduced leakage current in both forward and reverse operation increases energy harvesting yield in PV arrays compared to traditional arrays using Schottky diodes.
• D2PAK package is a drop-in replacement for conventional surface-mount Schottky diodes.

Availability, packaging and pricing

The SM74611 smart bypass diode is available in volume now from TI and its authorized distributors. Offered in a two-terminal D2PAK package that measures 10.2 mm by 9 mm by 4.5 mm, the SM74611 is priced at $1.50 in 1,000-unit quantities.