Rooftop solar photovoltaic electrical generation could provide 56% of Maine’s peak power

By Unity College | Mar 28, 2014
With its solar array and design, TerraHaus at Unity College is one of the most energy efficient college residence halls in the United States.


By Steve Kahl, Scott Graham, Bill Behrens, and Nicole Cyr

A recent editorial by the Bangor Daily News said that ‘Maine needs solar’ (March 8-9, BDN).  We agree.  Putting more solar photovoltaic electric panels on rooftops in Maine could save Mainer citizens big money according to a recent study by James Sewall Company of Old Town and ReVision Energy of Liberty and Portland.  LD 1252 recently passed by the legislature would extend incentive rebates for solar power, and we urge the Governor to sign this bill.  Maine is falling behind the rest of New England due to a lack of financial investment from the state to leverage the current federal tax credit. This hurts job creation in renewable energy and the growth of our state economy.

There is huge potential in solar power.  The amount of solar energy that falls on the earth each month is equivalent to the total known planetary reserves of oil, gas, and coal.   And unlike all fossil fuels, including natural gas, the price of sunlight is now and will forever be zero.  The earth intercepts 23,000 terawatts (a terawatt is 1 trillion watts) from the sun per year, compared to total annual planetary energy use of about 18 terawatts.  Forward-thinking countries like Germany and China have invested heavily in solar power for many years, despite their available sunlight being less than in Maine.

Solar photovoltaic (PV) panels convert solar energy directly to electricity.  While PV has been around for about 75 years, including powering space missions to the moon, the cost of PV equipment has plummeted in recent years, making solar PV similar in cost to grid electricity.  An upfront investment in solar equipment will generate electricity for decades, with no cost for fuel.  A recent study demonstrated that 40 year old solar panels were still producing more than 75% of their original wattage.

The solar industry already employs several hundred people in Maine today.  ReVision Energy alone has installed over two megawatts of solar PV which generates 2,400 MWH of electricity every year, equivalent to the power needs of 350 homes, annually offsetting 2.2 million pounds of carbon dioxide, and employing 65 professional staff at higher than state average wages.  Nationally, employment in the solar industry grew at nearly 20% last year, far greater than the rest of the economy.

ReVision has installed a number of solar arrays on schools and colleges, including Unity College, at no cost to the institution because they can then sell power back to the customer.  Unity’s Strategic Plan includes a net zero carbon emissions goal by 2019, and solar power is central to this goal.  Maine needs more of this type of creative use of solar power and needs the incentives to make it happen.   

Sewall and ReVision were funded in 2012 by the Maine Technology Institute to develop an automated mapping process that can identify the solar potential of buildings for rooftop solar installations.   This software, combined with aerial photography data, can determine the suitability of a home or business for solar power, and estimate the annual production in KWH. 

The project estimated the total potential of rooftop solar in Maine and the answer was consistent with estimates from other regions while also being startlingly large: 56% of the peak power needs of the state could be met with rooftop solar.  The reason that solar has this potential to offset peak power is simple: peak demand on the grid occurs on the hot, sunny, windless days of summer, exactly when solar PV is also peaking.  Moreover, the price per KW for peak power is typically 10 times the cost of non-peak power, and it is generated in the dirtiest, CO2 emitting, power plants.  And yet the sunlight is free.  The more solar power penetrates the market, the more costs will be lowered for consumers, the cleaner our air will become, and less CO2 will be emitted.

The output from this software analysis will provide solar installers with key information for expanding their businesses.  This project is an example of how renewable energy will grow Maine’s economy while reducing CO2 emissions, increasing the resilience of the electrical grid, and decreasing our national reliance on expensive and non-renewable fossil fuels.  Maine should be a leader in alternative energy development because the state that leads the nation in renewable energy will be the economic leader of the next century.


Steve Kahl is Director of Sustainability at Unity College; Scott Graham is Vice President at Sewall Company in Old Town; Bill Behrens is President and co-founder of Revision Energy; Nicole Cyr is Geospatial Manager at Sewall Company.

Comments (1)
Posted by: Susan Mondabaugh | Mar 29, 2014 07:33

I was heartened to see that our local representatives Ed Mazurek and Joan Walsh supported LD 1252.  There seems to be a common misconception that solar doesn't work in Maine, which is totally unfounded.  The information presented above is right on target.  Not only does solar power work well, it does so much more unobstrusively than wind turbines in terms of noise, harm to wildlife (birds), and changing the panoramic landscape of this beautiful state we live in. 

Let's encourage our senators and representatives and Governor LePage to pass bill LD 1252 and support this clean, quiet form of alternative energy.

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