Portland, Maine — In a finding that could affect the outlook for renewables integration,solar facilities with smart inverter technology can provide key grid servicesat levels that are similar to, and in some cases better than, conventionalpower plants, according to a study by California's grid operator, theDepartment of Energy's National Renewable Energy Laboratory and First Solar.
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"These findings mean renewable energy in the [California IndependentSystem Operator] footprint -- and beyond -- could be integrated into powergrids at a much higher level and faster pace than once believed," ClydeLoutan, ISO's senior adviser for renewable energy integration, said Wednesday.
The study comes amid concerns about how growing amounts of renewablegeneration will affect grid operations. The US has 25,000 MW of utility-scalephotovoltaic capacity, plus 1,800 MW of concentrating solar, according to thereport, titled "Using Renewables to Operate a Low-carbon Grid."
California is at the forefront in the shifting generation mix, withrenewable requirements that climb to 50% by 2030. The ISO has more than 9,000MW of grid-connected solar and expects rooftop solar to grow from about 5,000MW to 9,000 MW by 2020. Also, the grid operator estimates an extra 20,000 MWof renewables may be needed to meet the state's renewable portfolio standard.
The ISO is being forced to curtail renewables during periods of growingoversupply, according to the report. The grid operator curtailed 2,000 MW ofrenewables on one day in April, it said.
"With increased frequency of curtailment, more opportunity is created ifthe industry can tap into the controllability of the renewable resources, andthus expand the carbon-free resources for such services," the report said.
Currently, utility-scale PV plants are typically not used by utilities orgrid operators for electrical grid services, according to the report.
In August, the ISO and NREL tested a 300-MW solar plant in Californiaowned by First Solar. The test aimed to show the plant's ability to followsignals from the ISO at sunrise, midday and sunset and how it performed inthree key areas: frequency control voltage control and ramping capacity.
The data from the test show how with advanced power controls aphotovoltaic plant can morph from being simply an intermittent energy resourceto one also providing grid services ranging from spinning reserves, loadfollowing, voltage support, ramping, frequency response, variability smoothingand frequency regulation to power quality, the report said.
The ISO said the most unexpected and significant benefit from the testswas the "agile" voltage support the solar plant offered when it produced powerduring the day and at night when it could absorb a small amount of power fromthe grid.
The ISO, NREL and First Solar intend to explore economic and contractualincentives that could be used to encourage solar facilities to providereliability services.
The ISO and NREL are also considering conducting simultaneous tests ofancillary service controls by solar PV and wind generation to understand howworking in tandem they can provide various combinations of ancillary services.
--Ethan Howland, firstname.lastname@example.org
--Edited by Keiron Greenhalgh, email@example.com