Utility-Scale DC Optimizer System

Ampt optimizer Ampt String Optimizers perform MPP tracking at higher granularity than central inverters, which improves energy harvest.

Image Courtesy Ampt

Ampt is a founding member of the HDPV Alliance, a solar equipment manufacturer association with the goal of developing lower-cost and higher-performing PV systems. The company’s Ampt String Optimizers are dc-to-dc converters developed specifically for large-scale PV applications. From an eBOS perspective, this design approach has a compelling value proposition, one that has gained traction in residential and commercial applications. I interviewed Mark Kanjorski, the company’s director of marketing, to learn more about deploying dc optimizers at scale.

SP: What are the basic components of an Ampt-optimized system? What are the benefits of this design approach?

MK: Ampt String Optimizers are dc-to-dc converters that put voltage and current limits on each PV string. This allows system designers to double their string lengths and reduce the number of combiners, disconnects and homeruns by 50%, which provides savings on materials, shipping and installation costs. The current limits allow installers to use smaller-gauge wire, which further reduces costs. Ampt String Optimizers also deliver full array power at a voltage that is near the maximum system voltage, so inverters can narrow their operating range and deliver more power, which effectively reduces the inverter cost per watt.

SP: How does an Ampt-optimized PV system compare to a conventional 1,500 V system?

MK: As an industry, we can lower the cost of solar energy by reducing the system cost or by increasing energy production from a given system. Both 1,500 V systems and Ampt-optimized 1,000 V systems reduce total system costs, but only the Ampt-optimized approach increases lifetime energy production. While 1,500 V systems increase the string length by half to remove 33% of the eBOS components, Ampt doubles the string length to remove 50% of the eBOS components. So Ampt not only removes more eBOS but also allows developers to keep using lower-cost 1,000 V–rated components. Using string optimizers in PV systems increases the MPPT resolution to increase lifetime energy production. That extra production results in higher project revenues.

SP: Can you describe Ampt’s field deployments to date and its path to a broader market?

MK: Most of our deployments are in North America, Europe and Asia. Our large-scale systems range in size from 1 to 2 MW to multiple tens of megawatts. In general, the qualification process for Ampt is similar to that of any supplier that serves the large-scale PV market. You need to have differentiated value to get in the door. Then you must demonstrate product quality and reliability, as well as strong pre- and post-sales support. Looking forward, we expect the market to increasingly deploy 1,500 V systems as the price premiums for 1,500 V modules and other barriers disappear. As that happens, Ampt will further optimize 1,500 V systems by eliminating another 50% of eBOS components and providing even more inverter savings.