
Redox flow batteries (RFBs) are an emerging technology suitable for grid electricity storage. The vanadium redox flow battery (VRFB) has been one of the most widely researched and commercialized RFB syst.

The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce, such as experiments by . installed the world's first rooftop photovoltaic solar array, using 1%-efficient cells, on a New York City roof in 1884. However, development of solar technologies stagnated in the early 20th centu.