Scores by kind of claim
Each kind of claim is scored on its own, out of 100: the share that held up, with the range it likely falls in. Fewer resolved claims give a wider range.
-
Factual claims
Statements about the present or the past, checked against the record: did they hold up?
72 64 80 -
Predictions
Statements about events outside the person's control, checked once they fell due: did they come true?
58 40 75
All types combined: 70 (likely 62 to 77, high confidence), from 52 claims: 43 factual claims, 9 predictions. It mixes kinds of claim in different proportions for different people, so compare people kind by kind.
Vinod Khosla's claims
“Remember, for the first 15 years we built solar voltaic cells, they took far more energy to produce than we ever got out of them in their lifetime.”
Vinod Khosla, venture capitalist, interviewee 28 September 2007 Interviews - Vinod Khosla (Frontline Heat) (PBS Frontline)
For the first 15 years solar photovoltaic cells were built, they took far more energy to produce than was ever got out of them in their lifetime.
Mostly true True in substance, wrong in a detail.
The second judge would not resolve this claim; the verdict shown is the first judge's.
What would count as true or false
Judge against the scientific record available as of 2007-09-28 on the energy payback of photovoltaics. True: life-cycle or net-energy analyses show that during the first ~15 years of PV cell production (roughly mid-1950s to early 1970s, or the first 15 years of commercial production), the energy used to make the cells exceeded the energy they produced over their lifetimes. Mostly true: the industry was a net energy consumer at that stage but over a period that differs somewhat from 15 years (e.g., 10–20 years), or the claim holds at the industry level rather than per cell. Mixed: the evidence is divided, or this held for some cell types or uses (e.g., early space cells) but not in general. Mostly false: the claim distorts something true, such as early cells having long energy payback times that still fell within their lifetimes, or the industry as a whole being a net energy sink because it grew fast, which is not the same as each cell failing to repay its energy. False: analyses show early PV cells generally produced more energy over their lifetimes than it took to make them.
Evidence
- Solar breeder: Energy payback time for silicon photovoltaic systems NASA Technical Reports Server (NTRS); report by J. Lindmayer, Solarex Corp. · April 1977
“It was found that the energy payback time for a typical solar panel produced by the prevailing technology is 6.4 years.”
- Solar breeder: Energy payback time for silicon photovoltaic systems (full report PDF) Solarex Corporation for ERDA/JPL (NASA CASI copy) · April 1977
“Since energy payback times as high as 40 years have been estimated for space cells, this relatively short payback time reflects the rapid progress made in terrestrial photovoltaic manufacturing.”
- How Long Does it Take for Photovoltaics To Produce the Energy Used? Professional Engineering (PE) magazine, National Society of Professional Engineers; by Vasilis Fthenakis (Brookhaven National Laboratory / Columbia) · February 2012
“EPBT OF PV SYSTEMS HAVE BEEN REDUCED FROM ABOUT 40 TO 0.5 YRS FROM 1970 TO 2010”
- Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development Nature Communications (via PubMed Central); Louwen et al. · 6 December 2016
“As a result, we show a break-even between the cumulative disadvantages and benefits of photovoltaics, for both energy use and greenhouse gas emissions, occurs between 1997 and 2018, depending on photovoltaic performance and model uncertainties.”
Reasoning
A 1977 Solarex report for ERDA/JPL notes that energy payback times as high as 40 years had been estimated for space cells (E2). Fthenakis reports that PV system energy payback times were about 40 years in 1970 (E3). Both are consistent with early cells taking more energy to make than they returned over a typical working life, although no source states the cells' lifetimes. The same 1977 report gives 6.4 years for terrestrial panels of that time (E1), much shorter than the earlier space-cell estimates of up to 40 years (E2). The claim is broadly supported, with uncertainty about whether it held for all early cells and about the lifetime comparison.
Cite this claim
Vinod Khosla, “For the first 15 years solar photovoltaic cells were built, they took far more energy to produce than was ever got out of them in their lifetime.” (said 28 September 2007). Verdict: mostly true. Reliability API, claim c_ec2b6e50b061, method 0.1.0+c876030c. https://epistacklabs.com/claims/c_ec2b6e50b061
Claims without a verdict
Is a verdict here wrong, or do you speak for Vinod Khosla? Reply on the claim's own page, with the form at its foot (how replies work). Verdicts are made automatically; how verdicts and scores are made.