Chip Recovers Power Loss Due To Solar Panel Variability

STMicroelectronics claims it’s come up with the first IC to combine key power-optimization and power-conversion functions for solar generators. According to the company, it will allow multi-panel arrays, ranging from domestic rooftop-type equipment to larger installations, to deliver more energy at a lower cost per watt.

With the SPV1020, maximum power-point tracking (MPPT) can be applied individually for each panel. MPPT automatically adjusts a solar generator’s output circuitry to compensate for power fluctuations resulting from varying solar intensity, shadowing, temperature change, panel mismatch, or aging. Without MPPT, the power from a solar panel can fall by 10 to 20% if even a small percentage of its surface is in shadow. This disproportionate decrease may restrict the choice of site, or force the use of a smaller array to avoid shadows. In some cases, it can challenge the viability of the project.

The SPV1020 also enables distributed MPPT (DMPPT), which compensates each panel individually, in contrast to a centralized MPPT scheme that applies a “best-fit” compensation to all of the array’s panels. DMPPT is the most promising technique to improve the energy productivity of photovoltaic systems, because it maximises the power extracted from each panel regardless of adjacent module performance, even if a module has failed.

Implementing DMPPT usually requires a network of discrete components for each panel in an array. The SPV1020 replaces this network with a single chip, and integrates the dc-dc converter to step-up the panel’s low-voltage dc output to a larger dc voltage that produces line-quality ac power. By integrating MPPT and the dc-dc converter, the SPV1020 simplifies design and reduces part count, making DMPPT economical for solar generators across a range of power ratings and price points.

ST integrates all of the required functions in a monolithic chip via its 0.18-micron BCD8 multi-power process technology. BCD8 holds the key to combining power and analog functions for the dc-dc converter on the same chip—it’s the digital logic that performs the MPPT algorithm. This technology enables a smaller, more reliable, and longer-lasting solution than one built with discrete components. The IC’s advanced dc-dc converter architecture minimises the size and number of external passive components needed.

The SPV1020 comes in a 36-pin PowerSSO (PSSO-36) package. Engineering samples and evaluation kits are available now, with volume production scheduled for November.

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