The real EROI of photovoltaic systems: professor Hall weighs in.
The EROI of our various energy options, and its associated issues, may be the most important issues that will face future civilizations. The present discussion tends to vacillate between people who accept (or advocate) very high EROIs for solar vs people who accept (or advocate) very low such EROIs. I trust only one study, the one I did with Pedro Prieto, who has a great deal of real world experience and data. This study attempted to (conservatively) estimate all the energy used to generate PV electricity in Spain by following all the money spent (per GW) and using physical analysis where possible, and energy intensity of money where necessary. We found that the panels and inverters, which are the only parts measured in most studies, were only about a third of the energy cost of the system. As noted in the responses to Ugo’s last post we estimated an EROI of 2.45:1 in 2008 assuming a lifetime of 25 years and at the juncture with the distribution system. Studies that we think used more or less appropriate boundaries (Palmer, Weissbach) got similar results.
We recognize that subsequent studies to ours would probably have generated higher EROIs because of using panels of lower energy costs or higher efficiency. But there are many ways that it might be lower too. For example Ferroni and Hopkirk, who (despite, perhaps, some issues) have done us a good service by attempting to get actual lifetimes for modules, which were much closer to 18 years than infinity. This agrees with what happened in Spain when, due to post-2008 financial turmoil, manufacturers did not honor their guarantees and legally “disappeared”, leaving broken systems unfixed. (And what happened to all those “surplus” Chinese panels that were never used?
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