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Tom, Yes, but if you use individual 2V cells, you can pull one failed cell out of the string and get by just fine by adjusting setpoints down by 8% (11/12ths). You'll lose 8% of capacity until a cell is replaced; or, if the failed cell is the first to go at end-of-life, just live with the remaining 22V bank while collecting funds for the replacement set ("You have been setting aside some money each year for that set, haven't you?"). Using two strings is fine, but if the smaller strings are made up of 4V or 6V cases, you no longer can remove just one cell. Rather, you must disconnect one string and live on 50% capacity (or 67% with two out of three strings) until a replacement is secured. Based on the above, I'd usually go with a single string of the best batteries I can find. Personally, I like what Chris Worcester wrote: My one string of 1476 AH IBE 2 V cells went 19 years before retiring them to a neighbor’s off grid system, where they are now working. One string has my vote! as I just put that exact size of IBE 2V cells in my own home. Here's hoping I get another 18 years and 10 months out of them.Allan
Allan Sindelar
al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com On 5/31/2011 5:36 PM, Tom Elliot wrote:
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