Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake TPX IMAGES OF THE DAY

A solar panel is shown during installation on a residential roof in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Workers lift a solar panel onto a roof during a residential solar installation in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

A solar installer carries a solar panel during an installation at a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Workers lift a solar panel onto a roof during a residential solar installation in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Multiple homes with solar panels are shown in Scripps Ranch, San Diego, California, U.S. October 5, 2016. Picture taken October 5, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Solar installers from Baker Electric place solar panels on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

A solar installer from Baker Electric installs a solar panel on the roof of a residential home in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

A DC to AC solar converter is shown during the installation of a residential solar power system in Scripts Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

A DC to AC solar converter is shown during the installation of a residential solar power system in Scripps Ranch, San Diego, California, U.S. October 14, 2016. Picture taken October 14, 2016. REUTERS/Mike Blake 

Multiple homes with solar panels are shown in Scripps Ranch, San Diego, California, U.S. October 5, 2016. Picture taken October 5, 2016. REUTERS/Mike Blake 

Multiple homes with solar panels are shown in Scripps Ranch, San Diego, California, U.S. October 5, 2016. Picture taken October 5, 2016. REUTERS/Mike Blake 

Multiple homes with solar panels are shown in Scripps Ranch, San Diego, California, U.S. October 5, 2016. Picture taken October 5, 2016. REUTERS/Mike Blake 

Multiple homes with solar panels are shown in Scripps Ranch, San Diego, California, U.S. October 5, 2016. Picture taken October 5, 2016. REUTERS/Mike Blake 

File photo shows a general view of solar panels used to produce renewable energy at the photovoltaic park, the biggest in Europe, during its official inauguration in Cestas, France, December 1, 2015. REUTERS/Regis Duvignau/File Photo 

File photo show a general view of solar panels to produce renewable energy at the photovoltaic park in Cestas, France, June 19, 2015. REUTERS/Regis Duvignau/File Photo

High tension transformers are seen next to solar panels used to produce renewable energy at the photovoltaic park, the biggest in Europe, during its official inauguration in Cestas, France, December 1, 2015. REUTERS/Regis Duvignau/File Photo 

File photo shows a general view of solar panels used to produce renewable energy at the photovoltaic park, the biggest in Europe, during its official inauguration in Cestas, France, December 1, 2015. REUTERS/Regis Duvignau/File Photo 

Belgian scientists Marjolein Vanoppen and Sebastiaan Derese demonstrate the use of a machine that turns urine into drinkable water and fertilizer using solar energy, at the University of Ghent, Belgium, July 26, 2016. REUTERS/Francois Lenoir

Belgian scientists Marjolein Vanoppen and Sebastiaan Derese (R) demonstrate the use of a machine that turns urine into drinkable water and fertilizer using solar energy, at the University of Ghent, Belgium, July 26, 2016. REUTERS/Francois Lenoir TPX IMAGES OF THE DAY

A 20-megawatt photovoltaic solar power generation facility owned by SunEdison is shown in Hemet, California April 5, 2016. REUTERS/Mike Blake

Surrounded by high fencing a 20-megawatt photovoltaic solar power generation facility owned by SunEdison is shown in Hemet, California April 5, 2016. REUTERS/Mike Blake

A SunEdison employee closes a gate to the companies 20-megawatt photovoltaic solar power generation facility in Hemet, California April 5, 2016. REUTERS/Mike Blake

A SunEdison employee enters the companies 20-megawatt photovoltaic solar power generation facility in Hemet, California April 5, 2016. REUTERS/Mike Blake

A sign on the entrance gate warns of possible venomous snakes and insects at the 20-megawatt photovoltaic solar power generation facility owned by SunEdison in Hemet, California April 5, 2016. REUTERS/Mike Blake

A 20-megawatt photovoltaic solar power generation facility owned by SunEdison is shown in Hemet, California April 5, 2016. REUTERS/Mike Blake

A SunEdison employee closes a gate to the companies 20-megawatt photovoltaic solar power generation facility in Hemet, California April 5, 2016. REUTERS/Mike Blake

A locked gate controls access to a 20-megawatt photovoltaic solar power generation facility owned by SunEdison in Hemet, California April 5, 2016. REUTERS/Mike Blake

A locked gate controls access to a 20-megawatt photovoltaic solar power generation facility owned by SunEdison in Hemet, California April 5, 2016. REUTERS/Mike Blake

A sign on the entrance gate warns of possible venomous snakes and insects at the 20-megawatt photovoltaic solar power generation facility owned by SunEdison in Hemet, California April 5, 2016. REUTERS/Mike Blake

A 20-megawatt photovoltaic solar power generation facility owned by SunEdison is shown in Hemet, California April 5, 2016. REUTERS/Mike Blake

A gate controls access to a 20-megawatt photovoltaic solar power generation facility owned by SunEdison in Hemet, California April 5, 2016. REUTERS/Mike Blake

Solar panels are seen on the roof of a car park in Mountain View, California April 7, 2016. REUTERS/Noah Berger TPX IMAGES OF THE DAY

A tower belonging to the Abengoa solar plant is seen at the "Solucar" solar park in Sanlucar la Mayor, near the Andalusian capital of Seville, southern Spain March 4, 2016. REUTERS/Marcelo del Pozo TPX IMAGES OF THE DAY

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. REUTERS/Eugene Tanner/Pool 

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. REUTERS/Eugene Tanner/Pool 

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. REUTERS/Eugene Tanner/Pool 

The Solar Impulse 2 airplane, flown by test pilot Markus Scherdel, flies off the coast of Oahu during a test flight from Kalaealoa Airfield in Kapolei, Hawaii, March 3, 2016. REUTERS/Eugene Tanner/Pool 

A field with heliostat mirrors are seen during the construction of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

Heliostat mirrors reflect their surroundings in a field at the construction site of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen TPX IMAGES OF THE DAY

A general view picture shows the foundations of a 240 meter (787 feet) solar-power tower, which is under construction in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

A vacuum lifter and crane moves a heliostat mirror during the construction of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

A worker is silhoutted as he works on the construction of a boiler at the building site of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

Heliostat mirrors reflect the sky in a field at the construction site of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

Construction workers install heliostat mirrors during the construction of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

Construction workers use a vacuum lifter and crane to move heliostat mirrors during the construction of a 240 meter (787 feet) solar-power tower in Israel's southern Negev Desert, February 8, 2016. The world's tallest solar-power tower is being built off a highway in the Negev Desert in southern Israel, its backers hoping the technology will gain a foothold in the solar market even if it remains a small player for now. Picture taken February 8, 2016. REUTERS/Amir Cohen 

A solar panel is placed on rubble along a street in the Douma neighbourhood of Damascus, Syria February 9, 2016. REUTERS/Bassam Khabieh 

Bricks are placed behind a fence near a closed brick factory on the outskirts of Beijing, China, January, 18, 2016. On the outskirts of Beijing, the disused factories of Chaomidian show the impact of China's drive to shut down thousands of small firms causing big pollution. Amid scrapheaps and idle machinery, the community has clean air these days - and no jobs. Picture taken January 18, 2016. REUTERS/Jason Lee

Dmitry Baikalov, a duty engineer, inspects equipment at the Abakan solar electric station in a suburb of the Siberian town of Abakan, Khakassia Republic, Russia, December 17, 2015. Owned by EuroSibenergo company of the En+ Group, the solar electric plant in Siberia with a generating capacity of 5.2 megawatt (MW) will be in operation on December 21, according to the official representative of the company. Picture taken December 17, 2015. REUTERS/Ilya Naymushin 

A general view shows solar panels used to produce renewable energy at the photovoltaic park during its official inauguration in Cestas, southwestern France, December 1, 2015. The solar farm of Cestas, the biggest in Europe, consists of 1 Million solar modules covering an area of 2,5 km2 of land and representing 300 MW of power. REUTERS/Regis Duvignau 

An electrical power pylon for high-tension electricity power lines is seen near a photovoltaic park in Cestas, southwestern France, December 1, 2015. REUTERS/Regis Duvignau 

An electrical power pylon for high-tension electricity power lines is seen near a photovoltaic park in Cestas, southwestern France, December 1, 2015. REUTERS/Regis Duvignau 

A general view shows solar panels used to produce renewable energy at the photovoltaic park during its official inauguration in Cestas, southwestern France, December 1, 2015. The solar farm of Cestas, the biggest in Europe, consists of 1 Million solar modules covering an area of 2,5 km2 of land and representing 300 MW of power. REUTERS/Regis Duvignau 

A general view shows solar panels used to produce renewable energy at the photovoltaic park during its official inauguration in Cestas, southwestern France, December 1, 2015. The solar farm of Cestas, the biggest in Europe, consists of 1 Million solar modules covering an area of 2,5 km2 of land and representing 300 MW of power. REUTERS/Regis Duvignau