The Best Batteries for Your Off-Grid Battery Bank

This advice will help you choose the best battery for backup energy on your off-grid homestead.

| December 2016/January 2017

Battery Power

Battery banks can provide stored energy to renewable energy systems between charging periods.

Photo by Terry Wild Stock

Only 30 years ago, an off-grid homestead’s photovoltaic (PV) system was likely to consist of two 35-watt modules and one or two car batteries. Such a system had no inverter, as reliable inverters were still years away. The typical 12-volt system powered little more than a few low-voltage lights, a car stereo, and a few 12-volt products developed for early RVs. But for power pioneers, this kind of system was heaven-sent — a wonderful alternative to kerosene lamps and engine-powered generators.

The batteries used in early PV systems weren’t designed for the deep discharges common in home use, so they often failed to hold charge after only a year or two. As a result, early deep-cycle batteries for homestead systems were adapted from other uses. The most common batteries were originally developed for golf carts, supermarket floor scrubbers, and mine cars. Only a few people could afford to order industrial-grade batteries directly from manufacturers.

Renewable energy systems should be sized so that the total amount of daily charging energy from all sources — PV, wind, hydroelectric, or generator — exceeds a home’s total average daily load. The role of the battery bank is to provide stored energy between charging periods — nothing more. When carefully planned and executed, the batteries in a home power system will run everything in your home — but “everything” will include far less than in a typical mainstream home.

Living well on a small and finite amount of electricity starts with careful adherence to three basic principles: Shift inappropriate loads to other forms of energy, reduce waste through efficiency, and use power in proportion to the amount available.

Efficient Use of Electricity

All forms of energy are not created equal. Electricity is a specialized, high-quality form that’s best suited to specific applications: lights, electronics, and motors, plus a few other specialized uses. By matching the best form of energy to its application, total electricity consumption can be greatly reduced while enhancing comfort and convenience. Five common uses of electricity in conventional grid-tied homes won’t typically show up on an off-grid homestead: space heating, water heating, cooking, clothes drying, and air conditioning. Each of these consumes too much energy to be appropriate when the supply is finite and the task is best-served by other forms of energy.

In the early years, PV modules were much more expensive than they are today, and batteries were less expensive. Early practice was to size for a week of storage capacity, but that led to small arrays and large battery banks, resulting in chronically inadequate charging. Modern systems are often sized for only two to three days of storage capacity, as long as the system includes a backup generator. As budgets allow, users add an additional array rather than increasing battery capacity.

7/6/2017 6:26:25 PM

Very helpful comparison of battery types for off-grid - it definitely makes sense to me to begin with a less expensive set and replace with an industrial set after we get adjusted to the maintenance. I also found this article that offers a helpful overview of all components of a solar system, helped me out a lot in the process.

7/6/2017 4:27:14 AM

Well said, Energy through solar panels will cut the electrity bills. Enerzea is one of the best Rooftop solar system suppliers which can effortlessly handle KW to ME scale solar power projects across the country.

mother earth news fair


Oct. 21-22, 2017
Topeka, KS.

More than 150 workshops, great deals from more than 200 exhibitors, off-stage demos, inspirational keynotes, and great food!