Technology

For those that don't read articles. The point here is that the energy in the liquid is not stored as heat. The sunlight directly changes the chemical nature of the liquid. Then it can be changed back later and this releases heat. So you don't need to contain it with insulation. And they've found a liquid to do this that the energy density is better than double that of Li-ion batteries.

There are still big hurdles like the inefficiency of sunlight usage as it only uses a small part of the spectrum. And acidification of the liquid which needs to be reversed to make the process continuous.