Costs have dropped, so more and more homeowners are interested in installing photovoltaic solar power on their rooftops. While the up-front investment is still significant, the “pay-back” time has dropped considerably. Many people are in the “clear” in as little as 10 years.
It is worth evaluating the decision to go solar from another perspective. When one installs a solar array, the decision creates demand for the manufacture of solar panels, the frames that hold them, and a variety of incidental connections. All these are made from materials extracted in mines and made in factories that use energy, often natural gas or electricity from traditional sources that emit carbon dioxide to the atmosphere. So, one might logically ask how long it takes to pay back the “carbon debt” to the atmosphere as a result of the installation of a new solar panel on your rooftop.
Several assessments are available with a wide range of answers depending on the type of photovoltaic that one chooses, where it is made, how it is displayed, and where you live. The manufacture of some panels, for example mono-crystalline silicon, is more energy intensive that others. The production facilities in some countries are more efficient than others. And, of course, where you live affects the amount of solar energy that you receive, the energy you generate, and the length of time it takes to pay off the “carbon debt.” The energy payback time for mono-crystalline silicon panels is about 1.7 to 2.7 years, whereas the carbon debt for some types of thin-film panels is paid off in as little as 0.7 years. Energy payback times have dropped considerably during the past decade, reflecting more efficient manufacturing processes and the benefits of volume.
So, from the perspective of the atmosphere, your decision to go solar is beneficial in about 2 years—less than the time it takes to pay back the monetary cost your initial investment. Last year, we installed 6.2 kW of panels at our house in Maine, and we have not been disappointed.
Garbinet, S., S. Belboom and A. Leonard. 2014. Life-cycle analysis (LCA) of photovoltaic panels: A review. Renewable and Sustainable Energy Reviews 38: 747-753.
Peng, J., L. Lu, and H. Yang. 2013. Review on the life cycle assessment of energy payback and greenhouse gas emissions of solar photovoltaic systems. Renewable and Sustainable Energy Reviews 19: 255-274
Stoppato, A. 2008. Life cycle assessment of photovoltaic electricity generation. Energy 33: 224-232.