Azuray PV power optimizers target shading

Azuray Technologies is launching two solar power optimizers at Solar Power International: the AP260 DC-DC power optimizer and the AC160 solar module performance monitor. Robert Batten speaks with Debra Vogler about the best ways to compensate for shading and other mismatches in the installation.

October 11, 2011 — Azuray Technologies has announced that it will introduce its AP260 DC-DC power optimizer and AC160 solar module performance monitor at Solar Power International. The products target the industry?s need for ?smart? shading solutions that monitor and optimize an entire array, while allowing installers the ability to provide shade compensation only on the solar modules that require it. The AC160 can be mixed with the AP260 when there is shade present on a PV array. The products can be used on both new and existing solar power systems to increase the solar energy production where output is impacted by shade, soiling and mismatch.

The AP260, based on Azuray’s AP250 power optimizer, supports real-time energy-output monitoring and safety shut-off features when used in conjunction with the ACM300 communications gateway.

The AC160 is a cost-effective monitoring and safety device that provides full system-level monitoring. The AC160 can be mixed with the AP260 to create a cost-effective power optimizer, monitoring, and safety environment when shading is present.

“We believe that shading is a common but underreported problem for the solar industry,” said Robert Batten, applications engineer, Azuray, in a podcast interview with ElectroIQ.com (listen below). “We have data from a report prepared for the California Energy Commission (by KEMA Inc., www.energy.ca.gov/2005publications/CEC-300-2005-019/CEC-300-2005-019.PDF) that shows that 87% of systems surveyed had some power production impact from shade. Over 40% would benefit from our optimizer.” Costs are decreased for end users because — unlike other products that require an optimizer to be placed on every module — the Azuray product only needs to be placed on the modules that experience shading.  



Batten further explained how the increase in solar energy harvest can be as much as 25%. ?We put a DSP on each optimizer that allows fast, accurate, local control of the optimizer and therefore provide fast and accurate tracking of the maximum power point over various irradiance changes, shading changes, weather conditions, etc.,? said Batten. And because the dynamic power optimization acts so quickly, it enables a higher power harvest in real-world applications, he noted. . The new optimizer compensates for mismatches between modules using the same principle whether it?s a mismatch because of soiling, or temperature differences, debris, manufacturing variations, etc. ?We?re still doing the same function?we?re taking the maximum power point current and voltage, and changing the voltage and current while maintaining the maximum power, and matching the output current of the optimizer to the ideal string current.? 

Batten explained that if a cloud passes in front of the sun, the irradiance can change by ~70-80% in a couple of seconds. Because the Azuray technology is mounted on the panel, it?s only measuring the behavior of one module, so the response is much faster. Conversely, because inverters look at the entire PV system, and can only track an average maximum power point, they can?t respond fast enough to system changes.

Both of the new products use automotive-grade components, are rated to 85°C and are designed to handle 25 years of operation in the harsh temperature environments where extreme thermal cycling is common (see the figure). The company says the new products are compatible with all major solar inverters and solar modules.

Operating Temperature
85°C Part 125°C Part
70 0.38 0.038
80
0.73 0.074
90
1.8 0.14
100
5.38 0.25
110
12.55 0.45
120
28.15 0.77
Figure. Temperature failure rate graph. Failure rate calculations are based on MIL-STD-217, component derating and over-stress predictions as calculated using QuARTPro software. SOURCE: Azuray Technologies.

The new AP260 and AC160 will be on display at the Azuray Technologies booth in Hall B, #1455 at Solar Power International in Dallas, TX, October 18-20 along with the AP250 and the AP300 smart junction box.

The AP300 is a certified smart junction box that integrates Azuray’s maximum power point tracking (MPPT) power optimization technology into a junction box provided by Renhe Photovoltaic Technology. Renhe Photovoltaic Technology will exhibit the AP300 in its booth 1450 at Solar Power International.

Azuray Technologies Inc. makes distributed solar electronics products for the PV industry. For more information, visit www.azuraytech.com.

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