[RE-wrenches] Off-Grid Sizing Case
Windsun@wind-sun.com
windsun at wind-sun.com
Thu Dec 3 10:18:52 PST 2009
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.
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Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
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----- 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
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From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Windsun at 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.
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Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
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