David, Windy's system sizing spreadsheet was first developed in the 1990s or so, when PV was expensive and lead (and copper) were relatively cheap. In those days, "one panel per battery" was a standard rule of thumb -but panels were seldom more than 55 watts, so 110 watts (6 1/2 A) was about standard for a pair of golf carts. That's a C/34 charge rate, max.
This past spring Windy and I revised that spreadsheet to reflect modern sizing and economics. It now works with any module cell count, for example. Contact me off list if you'd like a copy. (Be patient for the reply as I'm currently traveling.) > On Sep 15, 2015, at 6:04 PM, "Dave" <d...@independentpowerllc.com> wrote: > > The AEE catalog battery sizing template works well as it allows you to dial > back the days of autonomy needed. As I remember the old Dankoff Solar battery > sizing method pushed the watt hour size of battery banks to large, and > expensive, levels. > > The collective experience of this group, and others, has emphasized designing > off grid pv system's where the primary consideration is ample PV array sizing > and where the storage battery is sized in the C/10 range. With lower module > prices this has been practical for a few years now and it has been > demonstrated that smaller watt hour battery banks have proven to be not only > cost savers but also perform well for years as they live in a system where > they are very likely to be fully charged on a regular basis. > > Even here in northern Vermont where we experience late fall and winter daily > peak sun hours in the 1 hr/day average range, designing large battery banks > has been frowned on for many years out of my shop. Oversize the pv array and > run the generator when needed. > > David Palumbo > Independent Power LLC > 462 Solar Way Drive > Hyde Park, VT 05655 > 802-371-8678 cell > > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On > Behalf Of Chris Mason > Sent: Tuesday, September 15, 2015 5:39 PM > To: RE-wrenches > Subject: Re: [RE-wrenches] Battery bank calculator > > Homer can do it but it is expensive. > http://www.homerenergy.com > > On Sep 15, 2015 9:31 AM, "RE Ellison" <reelli...@gmail.com> wrote: > I don't think it can be done accurately with a sizing tool i've actually > never heard of a tool at least not that I can remember > > There's far too many variables. > Everything from loads to solar isolation as well as the habits of the > individual occupants and the appliance selection in the home > > The old joke used to be calculate what you needed for three days and then > double it as far as battery bank size > > Just a few thoughts, batten five dollars will get your cuppa coffee and a lot > of convenient stores > > Bob Ellison > > > > > On Sep 15, 2015, at 9:21 AM, gary easton <g...@arp-solar.com> wrote: > > > > anyone have a suggestion for a battery bank sizing tool? > > > > -- > > Sent from Gmail Mobile > > _______________________________________________ > > List sponsored by Redwood Alliance > > > > List Address: RE-wrenches@lists.re-wrenches.org > > > > Change listserver email address & settings: > > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > > > List-Archive: > > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > > > List rules & etiquette: > > www.re-wrenches.org/etiquette.htm > > > > Check out or update participant bios: > > www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org >
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