You can use superconductors to create Josephson junctions, which can be used for standard logic operations (but also useful in quantum computers). These junctions are much more efficient and much faster than transistors.
These particular superconductors will not be useful for transmitting power because the effect breaks down at very low current limits in this material, but they will be very useful for studying superconductors.
So contrary to what you said, these will in fact not be useful for power transmission, but could be useful for CPUs and GPUs, and could lead to computers that are hundreds or thousands of times faster and more efficient than what we have today.
To be fair this material may never see a practical use though.
TLDR; the front side is 23% efficient, and the rear side 20% efficient.
They don't actually give an overall efficiency but it implies a total of 43%. They compare this to typical panels also at 23% efficient, so it's really remarkable if true. Other emerging solar tech is up to about 32% but if that could also benefit from multiple layers then total efficiency could become insane.
Seems a little too good to be true, really, but great if so.