About the system

Updated: 09/20/2009

With the advent of 2008 and the new season of This Old Shack, we have updated the battery bank to 5 group 31 (110 amp hour) batteries. We are also using only wet cell batteries now, checking the condition of each cell with a hydrometer (a turkey baster like thing with floating balls that shows you how much charge is in the battery cells) The new bank is doing very well and the solar panels are able to keep the charge at full when we are not at the shack. We're using the same batteries but have reconfigured the bank so the batteries with the lowest specific gravity are in the center of the bank. Our charging regimen is also new and has sped the charging times by 20% or so. We have three charging options. First, the solar panels, which keeps the bank topped off when we aren't at the shack. Second, the new 2.4 kw generator has a 10 amp 12 volt output. We connect  that to the weaker center battery. Then we use the Schumacher Smart Charger at 20 amps through the ends of the bank.

The batteries are connected in parallel, which keeps the volts at 12 and adds the amps of the batteries together.

Here's how a Parallel connection of batteries works.

[March 5, 2006] Points to ponder

• Keep it simple – Complexity lowers reliability and increases the need for technical support.
• Understand system availability – Achieving 99+ percent availability with any energy system is expensive.
• Be thorough but realistic when estimating the load. Many system "failures" have been the result of underestimated loads. Remember if you have 10 amp hours only 5 or 6 of them can be used!
• Check local weather sources – Errors in solar resources estimation can cause disappointing system performance.
• Know what hardware is available and at what cost. Tradeoffs are inevitable. The more you know about hardware, the better you can make decisions. Shop for bargains, talk to dealers, ask questions.
• Know the installation site before designing the system. A site visit is recommended to determine component placement, wire runs, shading, and terrain peculiarities.
• Install the system carefully – Make each connection as if it has to last 30 years—it does. Use the right tools and techniques. The system reliability is no higher than its weakest connection.
•  Plan periodic maintenance – Photovoltaic systems have an enviable record for unattended operations, but no system works forever without some care.
•  Calculate the life-cycle cost (LLC) to compare photovoltaics to alternatives – LCC reflects the complete cost of owning and operating a system. 

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