Jim, I worked on the design and installation of numerous systems for the State Parks here in MN, using a variety of end loads however most consisted of the configuration you mention. We used the Mapps exterior mounted uninsulated boxes because they are vandal-proof. I know because someone tried to use a pry-bar on one of them and never broke through. We also used the AGM batteries from Interstate, so far they have exceeded our expectations. This was well over 7 years ago and as far as I know, still putting out the required power. We did design the batteries for only ~10 % discharge during worst conditions (-20F) and used an LBC to ensure protection as the Morningstar charger could not meet our requirements. I would hope with MPPT you could minimize system cost/size, don't skimp on BOS, you've got to design for the long haul.
Mario Monesterio Best Power Intl. 651.428.8397 [EMAIL PROTECTED] ----- Original Message ----- From: North Texas Renewable Energy Inc To: [email protected] Sent: Monday, October 06, 2008 10:40 AM Subject: [RE-wrenches] Off grid outdoor lighting Wrenches a general contractor working on upgrades to a VA hospital has come up with the big idea to use a series of lighted directional signs and landscape lights along the driveway and walkways leading to the building complex. To come up with a design to power these standalone natural stone monuments to government overspending and using the GCs choice of 12 VDC, 24 W lamps, http://www.greenenergymgmt.com/t8.html , I began with my years old off-grid sizing worksheet. It dawned on me that simply scaling the design factors down by a factor of ten might not give the efficiency results like a full sized off-grid house would. I'm going on the assumption that off-grid design has become more fine tuned considering the choices of MPPT and other controller technology helping to extend battery life. Anyway, the entire BOS will be outdoors and battery housing will probably not be insulated from temperature extremes, considering that they may be in full sun all summer, I want ample ventilation. Probably will use 2-6V AGMs to power the 4 lamps through a Morningstar 10 A 12V controller. I looked for pre-manufactured DC lighting kits but came away with little that appealed to me. Unless someone can point me toward a very reliable kit I will go with a scratch built system, battery box on a short PV pole style. Any tried & true design advice would be much appreciated. best regards Jim Duncan North Texas Renewable Energy Inc 4029 Aragon Drive Fort Worth, Texas 76133 817.917.0527 [EMAIL PROTECTED] Serving North Texas since 1994. For more information www.ntrei.com References? http://www.findsolar.com/ ------------------------------------------------------------------------------ _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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