Story 1 of 4
How PV reliability grew up
Reliability testing for solar modules has a public history that starts in laboratories and space programmes and runs through today's international standards. Each date below links to its source.
- 1883
Selenium cells
Charles Fritts coats selenium with an ultrathin, nearly transparent layer of gold; the cells are less than one percent efficient.
Sources: Britannica, Charles Fritts; APS News.
- 1954
The first practical silicon cell
On 25 April 1954 Bell Labs (Chapin, Fuller and Pearson) announces the silicon solar cell, about 6% efficient. Some timelines, such as the US DOE’s, give 4% for the first cell, so we say “about 6%”.
Sources: APS News, American Physical Society; US DOE, The History of Solar.
- 1958
Solar power in orbit
Vanguard 1, the first solar-powered satellite, is launched on 17 March 1958.
Source: NASA, Vanguard Satellite, 1958.
- 1975 to 1986
JPL’s Flat-Plate Solar Array Project
The Flat-Plate Solar Array Project, managed by NASA’s Jet Propulsion Laboratory for the US Department of Energy, develops terrestrial module technology and reliability testing. Its goals for 1985 were modules with 10% efficiency, a 20-year lifetime and a price of $0.50 per watt (1975 dollars).
Source: JPL/NASA NTRS, JPL Publication 86-31.
- 1975 to 1985
Block buys and qualification tests
JPL buys modules in five blocks (I to V) and requires each to pass a set of tests such as thermal cycling, humidity, mechanical load and hail. An NREL paper, citing Whipple, reports that modules tested to Block V (specified in 1981) had failure rates under 0.1%, against 45% for earlier modules.
Sources: NREL, Photovoltaic-Reliability R&D Toward a Solar-Powered World (NREL/CP-520-44886); NREL, DuraMAT consortium paper.
- 1993
The first IEC module qualification standard
The block-buy test protocols, carried forward with others, become IEC 61215, first published on 30 April 1993.
Sources: NREL, DuraMAT consortium paper; IEC Webstore, IEC 61215:1993.
- 2013
Measuring degradation in the field
Jordan and Kurtz review nearly 2,000 field degradation rates from 40 years of literature and find a median of 0.5% per year.
Source: Jordan and Kurtz, Photovoltaic Degradation Rates: An Analytical Review (NREL).
- 2021
Today’s standards
IEC 61215-1:2021 (edition 2.0) sets the design qualification and type approval requirements; IEC states that its test results are not a quantitative prediction of module lifetime. IEC TS 63209-1:2021 adds extended-stress test sequences to compare the longer-term reliability of modules and bills of materials.
Sources: IEC Webstore, IEC 61215-1:2021; IEC Webstore, IEC TS 63209-1:2021.
