Dear Editor:

You, like a friend of mine, may be wondering what’s the story with all of these new solar PV systems that have remained largely “snowed under” for a few weeks. Are they producing power? Would it be more economical to install solar on the ground versus rooftop, so that the snow slides off the more vertically installed panels?

While I have lived in Maine with rooftop PV solar power for more than 25 years, I decided to consult an expert and friend, Paul Kando (Paul writes the Energy Matters column for several Midcoast papers and has been in the solar energy field for decades.).

Paul looked at the figures for his own two-year old, roof-mounted PV system and calculated that in Maine a typical solar system annually produces about 1,131 kWh of electric power per kW system size (the typical 5 kW system installed for New England households produces about 5,655 kWh annually); 70 percent (789 kWh) of the total electric power is produced from April through September.

In January and February there is little power produced — about 4 percent of the annual total. At CMP’s standard offer rate of $.15/kWh (which includes delivery and surcharges), this amounts to just $3.15/kW per month per kW system size or $15.75/month for a typical 5kW system. Paul suggests this is perhaps a loss that we solar PV system owners just have to accept rather than risk damage cleaning off our roof-mounted panels.

But what about roof-mounted versus ground-mounted systems, which are installed more vertically and by nature stay clearer from snow? Bottom line is roof-mounted systems are considerably less costly. The installed cost for the roof system (without any discounts or incentives such as the 30 percent federal solar tax credit, which Congress recently extended three more years) is currently $3,800 per kW or about $19,000 for a 5kW system. You would need to add another $960 per kW or $4,800 (5kW system) to pay for a ground-mounted system, nearly 25 percent above the cost for roof mounting. And it would take about 25 years to make up the cost difference just to have your panels naturally cleared.

So, don’t despair as March is just around the corner and roof-mounted solar PV systems will once again be generating abundant clean power from the sun, which we gladly share with neighbors through the power grid.

Anne D. (Andy) Burt

Volunteer with Wiscasset Sun CATs

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