Off-Grid Battery Options

This expert advice will help you pick the best battery bank to power your property.

Photo by Adobe Stock/haitaucher39

I bought my first solar panel in 1989, a 50-watt Solarex photovoltaic module. Along with an old motorcycle battery, some DC car lights, and a small radio, I created an off-grid room in the house I was renting. When the power was out, and even when it wasn’t, I had lights and music operating on stored solar energy.

When I built my home in the 1990s, it was far enough from utility power that an off-grid system made economic sense, in part because I could do the work myself. Solar panels were more expensive back then, and the only accessible, affordable battery technology available was lead-acid. I’ve had to replace my battery bank about every seven years since, despite different brands, sizes, and configurations. Meanwhile, improvements in chargers, inverters, and PV panels have made lead-acid technology feel more antiquated.

This article compares some of the qualities of lead-acid and lithium iron battery technologies for off-grid applications.

Breaking Down Batteries

Lead-acid batteries haven’t changed much in 100 years, and they have a long history of dependability and affordability. They’re typically named according to the electrode material used, and further defined by the electrolyte used. For example, “flooded” refers to liquid electrolyte that needs to be replenished periodically by adding distilled water. Various types of maintenance-free, sealed, or valve-regulated lead-acid batteries exist.

Batteries are designed for specific purposes. Starting, lighting, and ignition (SLI) batteries used in cars are engineered to release lots of energy in a short period of time, and then quickly receive a recharge. Deep-cycle batteries have thicker plates, allowing for greater energy storage capacity and deeper discharging. In this article, I’ll focus on deep-cycle, flooded lead-acid (FLA) batteries, because they’re the most likely lead-acid batteries to be used in off-grid applications.

7/18/2019 10:08:43 AM

Have you not looked at FLA AGM batteries? My understanding is they are a sealed lead-acid batteries offering some advantages over standard lead-acid batteries that might be worth the cost. More than a standard lead-acid battery but quite a bit lower still than a LFP battery.

5/20/2019 4:15:32 PM

There is another battery option that I never see reviewed; the Edison, Nickel-iron battery. This battery is available from 'iron-edison' and is, I believe, is the best battery for off grid or standby.use. It is rated for 11,000 cycles, 30 years. So most of us will buy these only once. It can be fully discharged with no negative affects, but 80% is recommended. The life lifetime cycle cost is $0.090 per kWhr . much lower than lead-acid or lithium-ion. see,

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