1414 are best suited where heat can be used as well as energy (Combined Heat and Power (CHP). The process of turning heat back into electricity from molten silicon is only around 50% efficient I believe (certainly much less than a conventional battery (80-90%), or pumped hydro (typically 75-80% except for Snowy Hydro 2.0 which is only 65%). If they can use the excess heat for other purposes, well and good, otherwise it is just an inefficient battery, even if inexpensive.
Alternatively, if they were able to heat the silicon using say solar reflectors like the Port August plant to be built by SolarReserve, it could be different equation: The latter is heated from solar reflectors, thus capturing energy from the entire heat/light spectrum, while if 1414 is heated from electricity powered by solar panels, it is capturing around 20% of the sun's energy (20% is typical efficiency of a solar panel), so while SolarReserve may also be less efficient at turning heat into power (in their case via steam turbine I think), it has also been much more efficient at capturing heat energy directly from the sun rather than via conversion of light to electricity and back to heat.
I'm not trying to be negative - just telling it how I see it. It does appear to be a very good energy storage technology, may just need some work on getting energy in and out more efficiently. It's always good to see new innovation and I wish them well.
