A tool for optimal operation and design of batteries and its applications to self-consumption

Abstract

This paper presents a tool for optimal operation and design of batteries and its applications to self-consumption. The recent improvements in capabilities and costs of battery storage technologies might enable new business opportunities. Battery storage is key for operating and managing hybrid off-grid, microgrid and self-consumption systems. The feasibility of integrating batteries in these systems has been shown in previous studies, but the profitability of these business opportunities needs to be demonstrated. The profitability of these opportunities depends on the technical restrictions of the batteries, the behavior of the demand, the grid restrictions, and the regulatory constraints. The analysis of the profitability requires an appropriate model. In its most generic formulation, the model considers electrical and thermal demand, photovoltaic and wind generation profiles, conventional generation and cogeneration, demand response capabilities, and heat pumps and resistors for conversion of electrical power into thermal power. The behavior of batteries is modelled with penalization costs for cycling and for levels of stored energy above or below the recommended margins, ensuring that they are dispatched in a conservative manner to prolong their lifespan. For systems connected to the grid, the maximum power and the limits on feeding excess energy are also considered. The tool is applied to self-consumption considering a hotel building with a photovoltaic panel on its roof. Different business opportunities are studied such as storing the excess generation from renewable energy sources, reducing the power bill, or performing price arbitrage. The developed model compares combinations of batteries of different power ratings and capacities, along with different grid connection contracts to determine the cost for each. To do that, it considers the best allocation of the energy resources, both electrical and thermal, to minimize the total costs of the system. For comparing grid contracts, two variable costs are considered: one related to the maximum power rating, and the other to the energy consumption.