Swanson's law is the observation that the price of solar
photovoltaic module
Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commerciall ...
s tends to drop 20 percent for every doubling of cumulative shipped volume. At present rates, costs go down 75% about every 10 years.
Origin
It is named after
Richard Swanson, the founder of
SunPower Corporation, a solar panel manufacturer.
[ Note: Read more about current innovations in solar technology.] The term ''Swanson's Law'' appears to have originated with an article in ''
The Economist
''The Economist'' is a British newspaper published weekly in printed magazine format and daily on Electronic publishing, digital platforms. It publishes stories on topics that include economics, business, geopolitics, technology and culture. M ...
'' published in late 2012.
Swanson had been presenting such curves at technical conferences for several years.
Swanson's law has been compared to
Moore's law
Moore's law is the observation that the Transistor count, number of transistors in an integrated circuit (IC) doubles about every two years. Moore's law is an observation and Forecasting, projection of a historical trend. Rather than a law of ...
, which predicts the growing computing power of processors. Swanson's Law is a solar industry specific application of the more general
Wright's Law which states there will be a fixed cost reduction for each doubling of manufacturing volume.
Technical Background
The method used by Swanson is more commonly referred to as ''
learning curve
A learning curve is a graphical representation of the relationship between how proficient people are at a task and the amount of experience they have. Proficiency (measured on the vertical axis) usually increases with increased experience (the ...
'' or more precise ''
experience curve'' analysis. It was first developed and applied to the aeronautics industry in 1936 by
Theodore Paul Wright.
There are reports of it first being applied to the photovoltaics industry in 1975, and saw wider use starting in the early 1990s.
Crystalline silicon
Crystalline silicon or (c-Si) is the crystalline forms of silicon, either polycrystalline silicon (poly-Si, consisting of small crystals), or monocrystalline silicon (mono-Si, a continuous crystal). Crystalline silicon is the dominant semicon ...
photovoltaic cell prices have fallen from $76.67 per watt in 1977 to $0.36 per watt in 2014.
Plotting the module price (in $/Wp) versus time shows a dropping by 10% per year.
[ License: cc. Note: Appendix F. A trend extrapolation of solar energy capacity.]
See also
*
Economies of scale
In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of Productivity, output produced per unit of cost (production cost). A decrease in ...
*
Growth of photovoltaics
Between 1992 and 2023, the worldwide usage of photovoltaics (PV) increased exponential growth, exponentially. During this period, it evolved from a niche market of small-scale applications to a mainstream electricity source. From 2016-2022 it ha ...
*
Learning curve
A learning curve is a graphical representation of the relationship between how proficient people are at a task and the amount of experience they have. Proficiency (measured on the vertical axis) usually increases with increased experience (the ...
*
Log–log plot
In science and engineering, a log–log graph or log–log plot is a two-dimensional graph of numerical data that uses logarithmic scales on both the horizontal and vertical axes. Exponentiation#Power_functions, Power functions – relationshi ...
*
Moore's law
Moore's law is the observation that the Transistor count, number of transistors in an integrated circuit (IC) doubles about every two years. Moore's law is an observation and Forecasting, projection of a historical trend. Rather than a law of ...
*
Photovoltaic system
A photovoltaic system, also called a PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to abso ...
*
Wright's Law
*
Engelbart's law
References
{{reflist
Photovoltaics
Rules of thumb
Technological change