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Can your solar rooftop put a dent in climate change?

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At the United Nations climate talks currently underway in Paris, the focus is on energy – and rightfully so: more than 70 percent of the world’s greenhouse gas emissions come from energy-related sources like electricity production, heating, and transportation.

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More than 70% of the world’s greenhouse gas emissions (GHG) come from energy-related sources. (World Resources Institute, 2015)

Among strategies to combat climate change, low-carbon energy sources like solar and wind are indispensable. Making electricity with solar panels, for example, entails 91% less CO2 pollution than using natural gas, and 96% less CO2 than coal. Not to mention the sun won’t run out of fuel for another 5 to 7 billion years.

Going solar is the simplest and biggest action a home or organization can take to reduce its carbon footprint. It’s already cheaper for an energy customer to buy solar power instead of buying grid power in many places. The logic behind solar as an effective weapon against climate change, however, lies in its scale: the exponential growth of solar adoption in the last five years is a testament to what is possible.

Even considering this phenomenal growth, can solar power move the needle on climate change? And can distributed solar in particular – installed in places like residential rooftops, commercial buildings, and community-sized solar arrays – add up to meaningful reductions in CO2?

Solar power has the momentum to cut CO2 pollution at scale

Analysts anticipate that solar will be integral to an energy future that supports a healthy planet. The International Energy Agency has outlined how solar panels (a.k.a. photovoltaics, or PV technology) could generate up to 16% of the world’s electricity by 2050; investment bank UBS puts that number at 25% in a “high solar” scenario; researchers from Stanford University envision an even brighter future, in which more than 50% of countries’ electricity comes from solar.

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Solar PV has the momentum to become an integral part of world energy supply. By the end of 2015, global solar capacity will exceed 200 gigawatts – enough to power the entire state of California (the 8th largest economy in the world). Chart from REN 21.

Simple math suggests that solar power could solve a meaningful chunk of the CO2 pollution problem — the leading cause of global warming. Consider a major-emitting country, like the US or China, where roughly 40% of CO2 emissions come from the electricity sector. Were the country to shift to getting one fourth of its electricity from solar power, it would effectively cut 10% of the country’s CO2 pollution. Combine that with nine similarly large-scale climate solutions– from any of an array of technologies and innovations – and you start to halt global warming.

While solar is most obviously a tool to decarbonize our electricity supply away from coal and natural gas, the convergence of solar power and electric vehicles can likewise move the needle on climate change – by reducing the transportation sector’s oil-driven CO2 emissions.

Distributed solar power is shaping up to be a major part of solar’s growth

Alongside large-scale solar power plants, how big of a role can distributed solar power have in reducing CO2 emissions?

In many countries, it accounts for half or more of a country’s installed solar photovoltaic capacity. And market research suggests that over the next decade, more distributed solar PV will be installed globally than utility-scale PV.

Today in the US, distributed solar represents roughly half of installed solar power capacity. In leading solar countries like Germany and Japan, the proportion of distributed generation is even higher. India aspires to increase its solar power capacity twentyfold by 2022, and is aiming to install 40% of it on rooftops. Other emerging economies, from Kenya to Bangladesh, are ramping up distributed solar to provide low-carbon grid power and also to expand off-grid energy access.

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The surface area of US rooftops, if covered by solar panels, is large enough to meet 60% of the country’s electricity needs in 2050.

Distributed generation can also help communities adapt to climate impacts that are inevitable based on yesteryear’s global warming pollution. That’s because distributed systems can be designed to provide local backup power in case of grid failure, such as after unusually intense storms. Moreover, solar power systems (both distributed and large-scale) can help regions adapt to climate change effects like drought conditions: all things considered, solar PV technology uses a trivial fraction (as little as 1/200th) of the water used at a typical power plant.

Realizing solar power’s full potential to cut CO2 pollution is a matter of choice and policy

Solar power’s global momentum is good news for curbing climate change – it’s a low-carbon solution that we know works, that creates jobs, and that can be deployed at scale.

It’s concerning that a number of utilities in states like sunny California and Nevada want to stifle distributed solar power. Instead of innovating to develop the grid of the future, dozens of utilities are fighting policies that fairly compensate energy customers for contributing clean power to the electric grid. It’s a clear case of utilities seeking to protect their profits, rather than protecting than the planet or the interests of their customers.

We need policies and business models that embrace all forms of low-carbon energy – and that create opportunities for everyone to adopt clean power. It’s critical that we have the right policies in force on the ground today – in US states and beyond – that allow clean energy to grow at a pace that matches the urgency of the problem it’s solving.

Because with every solar rooftop, we all advance that much closer to solving the climate challenge.

Note: Calculation that today’s global solar PV capacity is enough to power California, is based on 200 gigawatts of global PV capacity, an assumed 15% capacity factor, and state-level data on annual electric consumption.