High-Voltage Solar Cell Sparks New Uses For Photovoltaics

Exploiting the properties of its silicon-on-insulator (SOI) semiconductor technology, Clare has developed a solar cell that produces a floating source voltage up to 7.5 V. With this capability, the CPC1810 can serve new applications where standard solar cells with a 0.6-V output cannot be used. For instance, Clare's solar cell could provide trickle charging for batteries. Or, it could be used as a light-detector in unpowered applications.

Clare, an IXYS company known for building solid-state relays, took advantage of SOI's low-leakage properties to integrate multiple p-n diodes on a single piece of silicon. That feat cannot be readily accomplished with standard junction isolation technology because of the leakage currents that result. But with SOI technology, diodes can be strung together, and these strings may be paralleled to scale the solar cell's output voltage and current. Following the introduction of this first 7.5-V, 12-µA output solar cell, the company will introduce a family of products with voltages ranging from 2 to 30 V and currents ranging from 12 to 200 µA.

Beyond device scaling, the technology also will enable the development of mixed-signal ICs that combine solar cells with related functions. Now sampling, the CPC1810 costs $0.75 each in 10,000-unit lots.