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Old 01-30-13, 01:10 PM   #8
gasstingy
Journeyman EcoRenovator
 
Join Date: Feb 2010
Location: Arab, AL
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Trevor,

As you haven't built the garage yet, be sure to site it true south when you build it. If there is to be any roof penetrations, be sure it {they?} are not on the south facing side of the roof. Also, if I was using the roof for solar panels, I would make the pitch of the roof match the latitude since I wouldn't be doing a seasonal adjustment to the tilt. Sorry, it may seem like I am talking down to you and I don't mean it that way, just wanted to be sure. You might also want to have fairly large overhang sized for passive solar and an appropriate number of windows. These add very little to the building cost and can make a huge difference in the temperatures in the building, both summer and winter.

The standing seam roof premium over a corrugated metal roof would probably pay for itself in a couple of ways (I have a metal roof with the screws visible on my house).

First off, the savings in racking materials only benefits you with standing seam, not corrugated metal because of the clamps used to pinch the seams on a standing seam roof.

Second, a few of the screws on my metal roof have somehow backed themselves out. That put me on the roof fixing them. If those screws were located under your solar array, you might not notice the problem until the water dripped off the underside of your roof. And you would almost certainly need to remove panel(s) to repair it.

All that said, I have two solar arrays in my backyard, both ground mounted. The first is 1050 watts of 6 Sharp 175w panels. I built it in two increments, 4 panels with Enphase micro inverters and then 2 more panels to fill the rack I built with more Enphase micro inverters. The first part was built in early 2009 when I bought American made Enphase inverters with the cast aluminum housings. When I added the last 2 panels in the fall of 2010, the Enphase inverters were made in China, but I had no choice for this small array. Last Spring {2012}, I had a bad inverter that Enphase made up under warranty. It was one of the newer inverters manufactured in China.

When I built the second array, 5760 watts, I went with 24 Sharp 240w panels on a DPW designed ground mounted rack running to an SMA Sunny Boy 5000 inverter. My solar designer recommended against the 6000w inverter because he said it would drop off more at the lower end of my array output.

The comparisons I have done on output say the small Enphase array does better on the really nice solar days. They have produced in excess of the panel rated wattage in really cold, for Alabama, weather. I have not observed the Sunny Boy go past 5111 watts. Typically the Enphase hits about 92% of module rated wattage where the Sunny Boy stops at 89% of module rated wattage.

My personal preference is to buy American, and I may not make quite as much power this way as if I'd gone with Enphase inverters. Twenty four separate Enphase inverters and the Enphase monitoring unit would have cost more than the Sunny Boy did also.

Whatever you decide, I'm glad you are considering solar.

Just my two cents worth,

Mark
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