For your latitude, you see the same max. average yearly peak sun regardless of your fixed array tilted at latitude or latitude -15 degrees.
See http://rredc.nrel.gov/solar/pubs/redbook/PDFs/OH.PDF. Being taught old school we always used latitude, but now I use latitude - 5 degrees for optimal fixed tilt. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner _____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Drake Chamberlin Sent: Monday, January 04, 2010 8:30 AM To: RE-wrenches Subject: [RE-wrenches] Best angle - direct grid tie Hello Wrenches, My Solar Pathfinder Assistant (SPA) claims that the optimum tilt angle for the solar modules is latitude. I'm skeptical. The system being designed is a direct grid tie, ground mount. It seems to me that an angle of latitude will give a balanced angle for both summer and winter charging. Since there is far less energy available in the winter, is this balance really the best. Also, a flatter angle in the summer should gain more hours of sun, since the sun goes N of the E-W axis. With ballasted systems, the 15 degree angle is supposed to work just fine, due to better summer charging. Does anyone have an answer to what really is the optimum tilt angle for a direct grid tie system? Is the SPA geared toward off grid systems, or is latitude really the best? Thank you and best wishes for the New Year, Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648
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