You know we’re getting somewhere when record-shattering solar power efficiency marks are popping up faster than zombies at your local Comic Con, so let’s hear it for the California-based innovator Amonix, which has been setting records practically since it first started up in 1989. In the latest development, Amonix has just achieved a 35.9 percent rating for its concentrator photovoltaic module, under a standard rating system recently established through the National Renewable Energy Laboratory. So, let’s take a look inside and see what makes this module tick.
Measuring Solar Cell Efficiency
Before we get into the nitty-gritty, let’s take a quick look at solar cell efficiency in general. Measuring solar efficiency is a tricky business, especially when you want to compare a conventional photovoltaic (PV) cell to a concentrator photovoltaic (CPV) module .
The National Renewable Energy Laboratory has been working with a number of solar companies, including Amonix, to develop accurate measurements for CPV efficiency. The latest iteration comes under the rubric of the International Electrotechnical Commission Concentrator Standard Test Conditions, consisting of outdoor testing on 1000 Watts per square meter at a 25 degree Centigrade cell temperature over a period of time.
The Amonix test took place earlier this year, from February to April, with the world record of 35.9 percent being the result.
Inside The Amonix CPV Module
The Amonix 7700 modules were originally designed with silicon solar cells in mind. The new PV cells incorporate III-V multijunction technology, which combines several materials into one solar cell.
Solar Junction, which was spun off from research developed at Stanford University, shattered a world record of its own last fall with an efficiency rating of 44 percent for its solar cell based on “A-SLAM™” (Adjustable Spectrum Lattice Matched) materials.
Semiconductor Today has a detailed rundown of the propriety A-SLAM architecture, which includes an indium gallium phosphide top layer and a ‘dilute-nitride’ bottom cell of antimony-doped gallium indium nitride arsenide.
Solar Junction and Amonix formalized their agreement in March of this year. At the time, Amonix CEO Pat McCullough predicted a very short R&D period, stating that “The results of this collaboration, and its lower levelized cost of electricity (LCOE), will be revealed soon.”
More Than Just Efficient
The raw numbers of solar cell efficiency are important, but let’s also keep the bigger picture in mind. To bring the price of solar power down to parity with fossil fuels, there has to be a balance between high efficiency and low cost, including manufacturing and installation costs.
Water scarcity is another critical (and growing) issue for conventional ground-mounted CPV installations, which typically depend on water as a coolant. No matter how efficient your CPV module is, you’re going to face some daunting obstacles for site selection in the increasingly dry and fire prone western US.
Amonix achieved a workaround by developing a cooling system based on ambient air. The only water required for operation is a relatively small amount for routine surface cleaning, which could be trucked in rather than having to build new water supply infrastructure.
Also noteworthy is the module’s pole-mounted structure, which minimizes its land footprint.