Concentration of CO2 in the Atmosphere

Sonnen Batteries

This recent sonnen battery installation in New Hampshire is an ECO-12. It provides continuous 8,000 watt output along with 12kWh of standby capacity. It can be charged by the home’s 7.8 kilowatt AC solar array, the grid, or a back-up generator. Photo courtesy of Granite State Solar.

By George Harvey

In a way, the sonnen battery story started in 1997, with a decision by the roughly 2,500 people of Wildpoldsreid, a town in Bavaria, Germany, to produce their own renewable power. Organizations and individuals in the community began to install renewable generating plants based on all sorts of technologies. They included solar photovoltaic (PV) systems, wind turbines, bio-digesters, and small hydro projects. They supplied electricity, gas, and heat to households, businesses, and municipal offices.

The experiment was so successful that within fourteen years, Wildpoldsried was producing over 320% of the energy it needed, and exporting several million euros worth of electricity each year. Since the people of the town had made the investments into renewable energy, they found themselves entering a new era of prosperity.

In 2010, two people, Christoph Ostermann and Torsten Stiefenhofer, founded a new business in Wildpoldsried to make batteries. Sonnen GmbH makes batteries. (Nouns are always capitalized in German. Since the name is purposely un-capitalized, and therefore not a noun, we can assume it means “solar.” I will capitalize it at the beginnings of sentences.)

Sonnen brought their batteries to market first in Europe, and began selling them in markets of the United States and Australia shortly before Hurricane Maria struck Puerto Rico. The company helped after the disaster, installing battery support for a number of microgrids. It did this especially in the island’s interior and other areas seemed to be ignored by the federal government and some large corporations.

We should focus, however on the sonnen battery itself. Because it is based on LiFePO4 chemistry, the sonnen battery is somewhat like the RELiON batteries covered in the April issue of Green Energy Times article, “RELiON Lithium Batteries.” There are some important differences however. To learn more about sonnen’s batteries, we contacted Erik Shifflett, who runs Granite State Solar, of Bow, New Hampshire, together with partner Alan Gauntt, to install systems in New Hampshire and Vermont.

Granite State Solar is a company with some pride in its expertise and abilities. The systems it installs are designed to provide the best engineered solutions to meet each customer’s individual needs. For example, it has partnered with AllEarth Renewables so it can install tracking systems where that is the best option. It does not subcontract work, and instead provides year-round employment to about thirty employees.

Shifflett said that a couple years back he set out on a search for the best possible batteries for customers. His own solar company was growing, but the entire battery business was evolving rapidly, and he spent a lot of time and energy assessing the various offerings. He looked at the Tesla battery, of course, and such others as the Aquion battery, which was based on a nearly non-toxic chemistry.

What he found was that sonnen’s batteries stood out in ways that made it unique. Among these is the battery’s interesting designs that tie it to grid electricity and solar panels. The sonnen battery is the first battery with a charge controller and transfer switch built in. It has a built-in ability to be AC coupled. This engineering has an interesting implication. It can be charged by any AC power source. That includes not only the grid, but solar panels equipped with micro-inverters and even the old gas-powered generator.

Some of its design is as simple as it is impressive. The battery can reset the micro-inverter at a solar panel by a brief, very minor change in frequency. This can get the panels going if their micro-inverters have tripped in a grid failure. Conveniently, this will happen automatically.

The sonnen batteries have an impressive 10,000-cycle guarantee, which Granite State Solar has amplified with additional coverage of its own. In the end, the customer’s guarantee is extended to 12,000 cycles or twelve years. The sonnen batteries are available in a range of sizes from four kilowatt hours to sixteen. They also qualify for tax credits.

Granite State Solar’s employees have all been trained by sonnen, and they have been accredited according to the needs of their jobs. Please do not let that statement slide by without noticing an important implication: The receptionist has been trained by the battery manufacturer.

There is much more to the sonnen battery than we have room for. You can contact Granite State Solar for more. The website is

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