28 November 2011
In 2003, the flames of the Cedar Fire engulfed the city of Alpine, located on the outskirts of San Diego County in Southern California. Many homes were lost, but today many have been rebuilt. Jim Manns’ home is now what is called “rebuild,” but instead of building it back just the way it was, the Manns went solar.
The large, two-story Ranch-style home also had a large energy bill. The Manns’ grown children moved back in with a baby, so the growing household’s electricity bills could be as high as $350 a month. Not only did solar fit in with their highly energy efficient rebuild, but they saw solar as a way of reducing those bills, and with the great amount of roof space, they envisioned being able to “run the metre backward,” and receive some credit for the energy their panels produced.
It was because of the micro-inverters that they could design the array to match the shape with the house.
Bruce Bosworth’s company, San Diego Solar Install was chosen for the job, which Bruce said he started by removing all the concrete tiles on the southern facing roof. “I used the south facing roof, and needed so much of it that we reroofed the whole side with composition shingles and then put solar arrays on them.” The array design took 700 square feet of roof area.
Bosworth chose to use 36 240W Phono Solar modules with 36 Enphase M190 micro-inverters for a 6.8 A/C system. He said the Phono modules work well with the Enphase micro-inverters “They are a perfect match”. In fact, he said that he’s seen this system turn on under a bright moon. “No kidding,” he said. “At night when the moon is really bright, I’ve gone to my live monitoring system and sure enough, all 36 modules are registering a half a watt. That’s a total of 18 watts, no real production, “ but he added that, “it gives you an idea of the sensitivity.”
He went with the Phono 240 Mono modules simply because he thinks it looks better than the Polys, “although production is very similar ,” he added.
He mounted 25 modules in a row all on a Unirac SolarMount I, which he said is quick and cost effective, efficient in time and installation, plus flexible in design. What makes it especially quick and easy to use is the simple way it joins together, Bosworth said. He said that he was able to keep the modules “straight as an arrow”. It was because of the micro-inverters that they could design the array to make match the shape with house.
The system is currently generating credit and is able to sell back to the grid. The Manns, who own the system (it is not leased), receive a net metering credit after 1 January, 2012. They’ll receive a Federal Tax Credit of 30% off the total cost of the system when they do their taxes in April, and they got a state rebate upfront of 64 cents a watt (or $4,700). Unfortunately he noted that the California rebate will likely be exhausted in the next six months with the price drop in modules. “But the Federal credit is good until 2016.”
Bosworth, never short on enthusiasm, said he learned how effective the monitoring system is with the Enphase micro-inverters on this job. He was able to pinpoint shading problems and pinpoint module mismatch. "Some modules are rated for 240 but only do 235 on the best day or maybe 245. But because Enphase has a computer in every one, it helps you narrow down the module mismatch.” The other great thing about this installation the Manns’ house is that it is so obvious, Bosworth said. “It’s a big, long yellow house that absolutely everyone sees as they drive down South Grade Road on the way to the 8 Freeway.” And now that big yellow house is greener than ever.
Written by Anne Fischer, Managing Editor, Solar Novus Today. Follow me on Twitter @solarnovusanne.
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