Which solar-electric technology had the highest EROEI?
Energy Returned On (Energy) Invested, also known as EROI and as EROEI, has become something of a fashionable metric *but see footnote.
It is calculated by dividing the total energy delivered by the system throughout its whole lifetime, divided by the total energy required to build, operate, maintain (and ideally decommission) the system.
Please refer to specific peer-reviewed energy studies where possible.
Within scope for this question:
- PV - the different and distinct types of photovoltaics:
- Cadmium Telluride
- Polycrystalline silicon
- Monocrystalline silicon
- Amorphous silicon
- organic solar cells (perovskites etc)
- CPV - concentrating photovoltaics
- CSP - Concentrated Solar-thermal Power driving a turbine (pictured below)
are all in scope, along with anything I haven't heard of that converts sunlight into electricity, without going through convolutions such as biomass, wind or wave.
Out of scope:
Attempts at doing it purely through prices do not answer the question: price is emphatically not a useful measure of total energy input, because the factors of production (land, capital, enterprise, labour) are not zero-cost, and because the ratio of energy to other inputs varies hugely by manufacturing technique and by product. So that approach is explicitly out of scope, because it's just plain wrong.
Also out of scope:
- Solar thermal (that delivers heat but no electricity)
- indirect solar generation such as wind, wave and biomass
- tidal and geothermal
- coal, gas, oil, nuclear.
* footnote on EROEI: Whether or not EROEI has much significance is disputed:
- some tie the very existence of civilisation as we know it to society achieving some minimum arbitrary level;
- others consider that as long as a generation source has a value greater than one, then the economics matter, and the EROEI does not (except solely for its impact on the economics). IF EROEI is less than one, then it can still be useful: not as a generation source, but as a store or conversion of energy.