Off-Grid Sizing CaseThe rate of charging is not the real problem in most undersized systems, it is the fact that the batteries seldom, if ever, get fully charged. Given the ratio of PV vs battery capacity, I would suspect that their batteries have been chronically undercharged for ages. We usually recommend around 1 watt of pv per AH for a 12 volt system, 2 watts for 24 volt etc.
A generator is not usually the answer, because it may have to run for hours to get that final 5-15% of charge into the batteries. Generators are good for equalizing, not so much for general charging. .................................................................................................. Northern Arizona Wind & Sun - Electricity From The Sun Since 1979 Solar Discussion Forum: http://www.wind-sun.com/ForumVB/ .................................................................................................. ----- Original Message ----- From: Mark Frye To: 'RE-wrenches' Sent: Thursday, December 03, 2009 10:56 AM Subject: Re: [RE-wrenches] Off-Grid Sizing Case So being able to achieve C10 charging from the PV is not so important? Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com ------------------------------------------------------------------------------ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of wind...@wind-sun.com Sent: Thursday, December 03, 2009 9:51 AM To: RE-wrenches Subject: Re: [RE-wrenches] Off-Grid Sizing Case I would go with #1. The solar is obviously undersized for the battery bank he has. Another panel + MPPT should give him about 25-40% more, depending on temps etc. .................................................................................................. Northern Arizona Wind & Sun - Electricity From The Sun Since 1979 Solar Discussion Forum: http://www.wind-sun.com/ForumVB/ .................................................................................................. ------------------------------------------------------------------------------ _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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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