The tremendous amount of solar energy received by the earth makes it the most appealing renewable energy source. However, challenges posed by the intermittency of solar energy source necessitate the integration of efficient solar energy conversion with scalable energy storage systems. This thesis revolves around the study and development of solar flow batteries (SFBs), a novel approach that integrates solar energy conversion and electrochemical storage. The unique integrated design of SFBs offers a practical solution to provide uninterruptable power supply on demand by a single standalone device regardless of the ebb and flow of solar irradiation. Although connecting photovoltaics (PVs) with batteries, as adopted by some solar farms nowadays, can provide the same uninterruptable power supply, the high capital cost and large footprint of two separate devices limit the market cases feasible for this option. In contrast, monolithically integrated SFBs may represent a more compact, and cost-effective approach for off-grid electrification. My graduate research has focused on three interconnected aspects for SFBs: (1) understanding the operation mechanisms of SFB devices; (2) developing the design principles and modeling methods to maximize the performance of SFBs; (3) the demonstration and device optimization of SFBs. The body of thesis presented here constitute a significant advance toward a compatible approach for harvesting, storing and utilizing the intermittent solar energy with high energy conversion efficiency and energy storage density. With our continuously evoling understanding on SFBs, I have pushed the boudaries along various dimentions for SFBs. The conceptual breakthrough and technological advancements presented here not only shed light on the future developments of SFBs, but also should translate to other integrated solar rechargeble battery devices, offering strategies for improving the performance of those devices.