Re: [RE-wrenches] Evergreen

[Allan Sindelar]

Title: Re: [RE-wrenches] Fw: Evergreen

Dana, Thank you for this information. I would like to clarify what you wrote. We have long accepted that trackers may be expected to increase daily output by about 35-40% in the summer and 10-15% in the winter, due to the differences in the sun's seasonal elevation and the resultant length of the solar day. It sounds as if you measured the effective increase from approximately summer solstice - winter solstice and got a 32% gain. You previously got the same gain (33%) measuring from last winter solstice to summer solstice. This makes sense, as it averages winter and summer gains over two roughly equal periods, with variations (summer monsoons, etc.) being within acceptable error. And whether grid-tied, grid-tied with backup, or off-grid is irrelevant as long as you can compare and record the outputs of the two otherwise identical arrays, one tracked and one fixed. Do I understand this right? If so, it's good real-world data for design purposes. Allan Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com Dana Orzel wrote: This is for a grid tied with battery backup Outback system. The 32% increased gain for the tracker VS. fixed mount production is an average of the last 180 days and I checked it in the spring for the last 180 days [over the winter] and it was 33%. The 12 – Evergreen 180 watt modules produce about 65 -70% of our home and office’s electrical requirements. Thanks, Dana Orzel Dana, That 32% is a very useful number, and it matches with our experience as well. But I need to verify a couple of assumptions, please: Does this represent average annual production, rather than peak seasonal? And is it a grid-tied system? Thanks, Allan   Allan Sindelar

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