Value chain · CLM-0310
In plain terms
How much a solar farm can be relied on to replace a conventional power plant, measured properly, drops sharply as more solar is added to the same grid.
The claim as recorded
Effective load carrying capability (ELCC), which a 2015 open-access case study describes as "a measure of the amount by which demand could be increased after adding a generator while maintaining the same reliability level", is shown in that study to decline for solar PV from an average capacity value of 40% of nameplate at 5% penetration to 25.6% at 20% penetration, with the marginal capacity value falling below 20% of nameplate above roughly 15% penetration.
Scope and limits
One regional case study, not a universal figure; capacity value is system- and location-specific by construction of the method. The ELCC description rests on SRC-181 p.3 (PDF 6), which cites a 2011 NERC report for it (its reference [10], not held). SRC-181 cites Garver's 1966 paper "Effective Load Carrying Capability of Generating Units" (its reference [12]; SRC-180, closed access, not held and not to be bought, ON-404) only for "Garver's method", an approximation that estimates ELCC directly. No held source states that Garver defined or originated ELCC.
What it assumes
Case study using hourly load, PV and wind data based on Arizona Public Service, with load scaled to a 1,500 MW peak, and conventional investment options from the IEEE Reliability Test System (32 generators, 3,405 MW); capacity value computed with the paper's own probabilistic capacity-expansion model as displaced conventional capacity. Garver's method is cited in the paper as one of the approximation methods, not used as its framework.
Where it comes from
p.13 (PDF p.16): "5% of solar penetration (125 MW of PV) results in a displacement of 50 MW of conventional capacity" (40% of nameplate). "increasing the capacity of solar PV to meet 20% of the annual demand (500 MW of PV) with this resource would only displace 128 MW of conventional generation" (25.6% of nameplate). The paper's footnote 10 states that the ELCC and the displaced conventional capacity "yield the same results". p.14: "The marginal capacity contribution of PV... is above 40% of the nameplate capacity at low penetration levels (less than 2%). However, it falls below 20% for penetration levels above 15%, approximately."
Related records
- Answers question
- QST-021 not published in this release
Cite this
energyaperture.com/c/clm-0310
CLM-0310, Energy Aperture, as of 2015-08.
Connected records
Other published records linked to this one. A list, not a judgement.
- Cited in articles