Changes

The barrel can be refilled with either fermented beer or wort. Choosing to refill with wort could eventually lead to a lot of trub build up, however, there might not be any negative flavor effects from doing so. Wort will ferment in the barrel and might cause a blow off unless there is adequate headspace (in which case the brewer should top up the barrel after the wort ferments). Choosing to refill with beer that is first fermented with brewers yeast or with a mixed culture might be more practical for avoiding blow off issues and for group barrel projects for homebrewers because individual brewers can brew the refill beer at any time, and then meet to refill the barrel. See [[Solera#Yeast_Autolysis|Yeast Autolysis]] below.

The term "solera" has deep roots in the history of Sherry production dating back as far as the late 1800's. As such, the term has a fairly strict and traditional meaning in the Sherry and wine industry. See [https://www.sherrynotes.com/2013/background/sherry-solera-system/ this article by Ruben Luyten] for an in-depth definition of the solera system as it is known in the Sherry industry. As a part of the traditional solera system, multiple tiers of casks are used in the system. There appears to be no known use of the term "solera" in the wine industry to apply to a single tier blending system (this is referred to as "perpetual blending" in the wine industry). As such, some brewers argue that unless a solera consists of multiple tiers, such as the system at [https://www.youtube.com/watch?v=bjMB0E_KeYI Cambridge Brewing Co. for Cerise Cassée], which is the oldest known beer solera since 2004, that it is not a true solera. The alternative term "perpetual blending", which has been applied in wine world to refer to single vessel blending systems <ref>[http://www.champagneguide.net/information/glossary Peter Liem. Champagne Guide. "Glossary of Terms". 2009. Retrieved 03/06/2018.]</ref>, has been offered as an alternative and more accurate word to use for single-vessel blending systems.