Solar power

Now I can charge my car with the sun.

One of our other major summer projects was the installation of a solar-panel tracker from Solaflect Energy – a local company from Norwich, VT that designs, builds, and installs its custom solar-tracker system in households and small businesses around the Upper Valley. We’ve been interested in going solar for years, and finally decided to take the plunge. As an added bonus, it (indirectly) serves to fuel my new Tesla. Read on!

The Tesla can now be charged by Solar power.

Although today was foggy all morning and cloudy for much of the afternoon – this 6kW unit managed to reach close to its full-power output when the sun came out around midday. The tracker patiently follows the sun from sunrise to sunset, potentially supplying our house with all its needed power; if there is an excess, it is fed back into the electric grid to provide others with power (and rewinding our electric bill). The tracker is connected to the Internet (of course!) so we can monitor its status and power production at any time; below is a plot of the power production today.

x-axis is time; y-axis is power production in Watts; horizontal gridlines are at 1500, 3000. 4500, 6000 W.

As you can see, our first full-day of operation was not particularly productive; nonetheless, we still managed to produce 6.86kWh. Although my Tesla battery holds 75 kWh, I expect it will be a rare day when I need to top it up with more than a dozen kWh.

Our installation began a bit over two months ago, when a crew showed up to dig a hole and drop in a heavy concrete footing, then erect the tracker tower. (See the gallery for more.)

From there, a pair of underground cables connect the tracker to the house: one carries the power from the panels to the house, and the other carries an Internet connection. This connection allows Solaflect to monitor our unit for performance and for remote maintenance; it also allows us to track our power production on the Fronius app or website.

The local real-estate boom has incurred a severe shortage of skilled contractors, such as electricians, so there was a seven-week delay before the next crew arrived to install the solar panels on a rainy day in late October.

Installing the panels on our Solaflect tracker.

Yesterday, the local power company finally arrived to swap out our electric meter – replacing it with a meter that can count backward(!) as we power the grid from our panels. With the equipment now all installed, we were finally able to flip the switch and enable the tracker.

We turn on the flow of solar power to the home.

The tracker uses astronomical algorithms to remain orthogonal to the sun between sunrise and sunset, returning to a neutral vertical position to rest overnight. (Vertical helps to avoid snow accumulation!) An anemometer allows the tracker to monitor the wind – if strong winds or severe gusts are detected, it lowers into a horizontal position to ride out the storm.

Solar panels in snowfall.

We look forward to the next step: the installation of a battery storage system in the basement, which will allow us to store enough energy to power the household through hours-long outages on the grid. That installation has also been held up by a shortage of electricians. We’ll let you know when it’s ready! Meanwhile, here’s a sunset picture from two weeks ago, to give you a sense of its size and location; notice the panels’ backside is white.

The tracker follows the sun; at the end of the day we see the white backside.

See the gallery for more photos.

Author: dfkotz

David Kotz is an outdoor enthusiast, traveller, husband, and father of three. He is also a Professor of Computer Science at Dartmouth College.

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