Concentration of CO2 in the Atmosphere

Grid Tied with Battery Storage

Twenty-nine panels sitting on the roof. Photos courtesy of David Abjornson.

George Harvey

New Hampshire resident, David Abjornson, has had a desire to reduce his carbon footprint for a long time. He did not want to jump into a big system, however, and wanted to start off with a smallish one, just so he could find out what he was getting into.

Three years ago, he was ready to make his first move. Having looked around at the renewable energy businesses operating in his area, he decided to hire Granite State Solar to build a small solar array on a west-facing part of his roof. He wanted solar panels that were the highest efficiency he could get, and he wanted the best warranty he could get, so he decided to go with SunPower Solar 327-watt panels with integrated 320-watt micro-inverters. Eight of these were installed giving him a grid-tied system of 2,560 watts.

Abjornson was impressed by the quality of Granite State Solar’s work and the professionalism of its employees. He was also very pleased with the solar addition on his roof. In less than a year, he decided to go further.

The next step in his growing system was twenty-one more panels of the same model. This time, they would be installed facing south. He was so pleased with his experience with Granite State Solar, he again hired them to do the job. With twenty-nine solar panels in the system, it had grown to have 9,483 watts of capacity.

Abjornson learned a lot making these steps, and one thing especially stood out to him, something that is not obvious to many people. The fact that you have solar power does not mean you will automatically have electricity when the grid goes down. “If you have solar, you can’t use it without battery backup if the power is out,” he said.

Part of this is obvious. Solar panels do not produce much power when it is cloudy, and none at night. But even during a sunny day, the panels do not produce the type and amount of power most people want. The conversion of varying amounts of DC power to independently varying demands for AC power requires two things, a battery system and its support circuitry. Of course, Granite State Solar was able and willing to install the battery system.

Abjornson decided to get a Sonnen ECO-16 battery. This is an impressive system. It can produce 8,000 watts of power, which is probably more than most people would need. More to the point, it can produce 16 kilowatt-hours (kWh) of electricity. This is enough for a small family in a power outage to go for a full day or more, with moderate conservation. With strict conservation, the family could go much longer. Given the combination of 9,483 watts of solar power and 16 kWh of storage, Abjornson could, in theory, just keep going through almost any outage.

Charging a Tesla from the sun at home.

The way this works in practice is actually rather smart. The battery system has an internet connection and watches the weather to see what sort of conditions will come up. If it sees that bad weather is coming, it starts to prepare for an outage. When the electric grid stops producing power, the battery system does not come on immediately, but delays for about a minute. While this makes uninterruptible power supply for computers a good idea, it reduces safety concerns. The system similarly can know when the power is about to be restored.

Abjornson said, “It’s fabulous. I did it to save the planet, a little bit at a time.”

One might think that David Abjornson’s story was over, because his dream goal had been met. Such, however is not the case. One minor detail had to be completed to get the appropriate attention, the addition of one thing – a Tesla. Yes, he got it. Yes, he loves it. And yes, Granite State Solar was able to install a home charger, so Abjornson’s Tesla runs on solar power.

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