Solar in our Midst

Pole Mounted Solar for the backyard

A friend in Flourtown really wanted to go solar, except that she had a tiny roof and two beautiful gigantic spruce trees near her house which made it difficult.  However, she also lived at the end of a street and her backyard faced a field with trees in the distance. She decided to put up a 12 panel solar array mounted on a pole.  With the assistance of a solar installer, she worked through all the details including trenching the cable back to the house, and she now has a very large, and to some, beautiful, structure in her backyard. It is invisible to the street.

The system is rated for 3.5 kW (kilowatt), which means at peak sunlight she would get more power than she currently needs, even with the planned electric car and the high efficiency heat pump she hopes is in her future. Over  the course of the year she should see a net contribution to the utility grid with a check from PECO, our local power company,  to pay her for that extra power that has gone from her house to power other people’s houses.

On October 5th, 2016 she turned on her own personal electrical power plant. This is similar to solar on a rooftop, but feels more substantial when it sits in the back yard. The panels, US made by CertainTeed, are wired in series and lead into a giant inverter on the back of the pole with a meter showing power generation.  

On December 13th at 9:30 AM, when this picture was taken, it was generating 492 watts as the sun rose over the trees, increasing to 860 watts by 10 AM on a grey day.   Note that this was very near the winter solstice — in other words, hardly optimal “sun” time. 

There is an “eye” on the top of the panels that is watching the sun and it will tell the mechanism behind the panels to adjust the panels so they are at an optimal angle to the sun. This system does bidirectional tracking (east/west plus more/less tilted to the sky). This cost for this about $2200 more, but should increase output by 33%, estimated to generate about 4690 kWh the first year. 

In June, expect to see sunflowers planted along the walkway, that have known how to track the sun for eons. The solar panels reset to the southeast every night, ready for the sun to come up the next day.

This is a small system capacity by any standard, but felt enormous as we stood beside it, towering beside the decades tall spruce trees. In an effort to merge this large object with the landscape, the owner added landscaping around the panels to soften their visual impact, using only native plants, most of which will provide food to butterflies and bees, come warmer weather. Shocked by the size of the panels, the owner reached out to her neighbors to reassure them that the new plantings would mostly cover the backside of the panels, but most didn’t seem to be bothered by the visual, and instead complimented her.

The inverter, by Fronius, converts the direct current (DC) that is produced by the solar panels to alternating current (AC) that is needed for all the electrical loads inside the house.  The AC current is sent down a wire inside a conduit which goes underground then through the basement to a meter in the front of the house. 

This meter is paired with another meter that comes in from the power company. One meter calculates the energy being sent out to the power company and the other tracks the power coming into the house from the power company. There is also a very important shut off box that is needed to cut the power from the solar panels in case of a fire or other emergency.  She is working with the local fire house to figure out the best way to notify fire fighters about this box. It may be a sticker next to her “Save my pets” sign on her front door, already addressed to them.

We saw a cool tracking app made by Fronius, the company that made the inverter. This homeowner is now not only a tree-hugger but also an inverter hugger, saying she loves her Fronius! I can see why; the phone-based application shows the energy generated in the past few days, as well as the cumulative the CO2 reduction, the money saved, and equivalent trees planted. The EPA’s greenhouse gas equivalencies calculator shows that generating 4690 kWh with solar panels is like reducing 3.3 metric tons of CO2 from the atmosphere, or not driving 7899 miles driven by an average passenger vehicle, or switching 117 incandescent lamps to LEDs, or the carbon sequestered by 85 tree seedlings grown for 10 years. 

The cost of the system was just under $20,000.  She will get 30% of this back when she files her taxes because of the federal tax credit that is in place until 2019. She will also receive a small amount of money for the solar renewable energy certificates (SRECs) from the power company, a monthly savings on her electric bill since she won’t have to buy the electricity from PECO, plus an annual check for all the surplus energy that she generates.

She figures 8 to 9 years for this system to payback, but the real payback has already happened.  She loves her panels, loves her inverter and is very happy knowing she’s making her own clean power.

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