A record 4,143 MW of solar photovoltaics was installed in the US in the third quarter, with 3,200 MW being utility-scale PV installations, GTM Research said Tuesday in a report commissioned by the Solar Energy Industries Association.

The previous quarterly high was in the fourth quarter of 2015, with 3,284 MW of solar installed, according to GTM.

US solar installations drove 60% of new electric generating capacity additions in Q3 2016, a record quarterly market share, GTM said.

"Between Q1 and Q3 2016, solar accounted for 39% of all new electric generating capacity brought on-line in the US, ranking second only to natural gas as the largest source of new capacity additions," it said.

Total installed solar generation capacity in the US at the end of the third quarter reached 35,743 MW, up from roughly 10,000 MW three years ago, GTM said.

The utility-scale PV market continues to be the primary driver of solar installation growth in the US, while residential rooftop installations have slowed, it said. The utility-scale segment represented 77 % of solar PV installed in the third quarter of 2016.

"Driven by a large pipeline of utility PV projects initially procured under the assumption of a 2016 federal Investment Tax Credit expiration, the third quarter of 2016 represents the first phase of this massive wave of project completion, a trend that will continue well into the first half of 2017," said Cory Honeyman, associate director of US solar at GTM Research, in an accompanying statement.

California, which now has 15,251 MW of solar generation, added more than 1,000 MW of utility scale in Q3, GTM said.

GTM expects the US to install 14,100 MW of solar PV in full-year 2016, which, if reached, it said, would be 8 % above the 2015 total of 7,300 MW.

In the fourth quarter, GTM said it believes 7,800 MW of solar will come online, with "a massive" 4,800 MW of utility PV projects making up the bulk of that quarterly total. The consultants said that 19 utility-scale projects greater than 100 MW are expected to come online in Q4.

"More solar capacity is expected to come online in the second half of this year than has ever come online in a single year," GTM said.

More than 50% of the original utility PV pipeline intended for 2016 has "successfully pushed out interconnection into 2017, or later," it said. This roughly 6,000 MW "spillover" of utility PV installations was enabled by the extension of the federal Investment Tax Credit, which Congress approved in December 2015.

California's investor-owned utilities have "already procured enough renewables to meet their renewable portfolio standard obligations through the end of this decade," GTM said. "Despite dirt-cheap PPA pricing, the utility PV segment is struggling to reboot procurement given the degree of demand pull-in in 2016."

Even with PPA pricing consistently ranging between $35/MWh and $60/MWh, utility offtakers have only partly countered the demand rollback from utilities that over-procured in the past couple of years, GTM said.

As a result, over 70% of the 2017 utility-scale project pipeline procurement will come from entities other than utilities seeking to meet renewable portfolio standards, it said.

Corporate customers have already procured more than 1,500 MW of so-called off-site wholesale solar for post-2016 installation dates, GTM said.

--Jeffrey Ryser, jeffrey.ryser@spglobal.com

--Edited by Richard Rubin, richard.rubin@spglobal.com

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