At the heart of their performance lies the energy conversion rate – the efficiency percentage that measures how well stored energy is converted into usable power. Therefore, all parameters are the same for the research and development (R&D) and Markets & Policies Financials cases. The 2024 ATB. . Battery energy storage systems (BESS) are revolutionizing how we manage electricity. You can go off-grid with batteries, but it requires a lot of capacity and money, so most homeowners don't go this route. This change is driven by rising electricity prices, power outages, and the desire to be energy-independent.