Bypass devices replace junction box Shottky diodes

15th October 2015
Barney Scott

Microsemi has announced the LX2410A IDEAL solar bypass device, designed to provide a bypass path in PV module applications. Featuring the company's patented CoolRUN technology, the LX2410A reduces the cost and increases the reliability of photovoltaic solar modules by replacing the Schottky diodes in junction boxes with an under the glass, higher performance solution.

“Our LX2410A IDEAL solar bypass devices provide unique advantages over competing products, including thinner packaging and better lightning strike protection capabilities,” said Shafy Eltoukhy, vice president and business unit manager at Microsemi.

High current PV module applications require a bypass path as a protection mechanism to enable the array to produce power when one part of the array may be shaded or damaged. In addition the device is required to protect the array from lightning strikes.  Microsemi’s LX2410A is the industry’s only bi-directional surge protection device designed to handle up to 500A of surge protection in the forward and reverse direction, maximising lifetime robustness and reliability of the device.

The thin package of the LX2410A with 0.7mm maximum thickness is designed for mounting inside solar PV panels to shrink the junction box and reduce expensive copper wiring to and from the box. This minimises system expense and enables higher power PV modules with smaller junction boxes and less copper losses for higher efficiency. The pads of the package are 2.6mm apart to meet the IEC61730-1 and IEC61730-2 creepage and clearance requirements.

REC, the largest European brand of solar panels, has evaluated active bypass devices like the LX2410A in its next-gen solar panels. According to the company’s engineering team, the thin package and high efficiency of the LX2410A allow them to be installed under the front glass of REC’s solar panels, reducing system costs by eliminating the need for a large junction box and excessive connection wires. REC has produced more than 15m panels and is a PV technology leader with integrated manufacturing of polysilicon wafers, cells, panels and systems.

Unlike a Schottky diode, the LX2410A is an active device that has an extremely low voltage drop and reverse leakage current, resulting in increased PV module power output, negligible heat generation and temperature rise during operation. Its patented CoolRUN technology’s non-hiccup control eliminates EMI radiating from PV module strings.

“Active bypass devices will replace Schottky diodes for improved efficiency and robustness in the next-gen PV module designs,” said Dr. Heribert Schmidt of the Fraunhofer-Institute ISE, Germany, a leading research institute for solar energy systems. “The devices also optimise module construction for lower overall system cost.”

According to market research firm IHS, 57GW of PV power capacity is forecasted to be installed in 2015 worldwide, reflecting a 48% market growth since 2013. With each solar panel estimated at 250W and using three bypass devices, the total addressable market for these products is forecasted to be greater than 600m devices in 2015. Microsemi’s LX2410A is in production now.

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