Monte Carlo-Based Approach for Obtaining the Marginal Costs of Grid Reinforcement for the Accommodation of Rooftop PVs

Worldwide, the installed capacity of rooftop photovoltaic systems (PVs) has been increasing rapidly, faster than the traditional load increase rate. Differently from the loads, the simultaneity factor of rooftop PV generation is roughly 1.0, resulting in higher violations of technical and regulatory limits. One of the most widely adopted solutions to accommodate rooftop PVs is to perform grid reinforcements, such as reconductoring and circuit sectionalization. In several countries, the investments in grid reinforcement are transferred to the customers as energy tariff, impacting the economy. Because of that, the Brazilian Electricity Regulatory Agency (ANEEL) is dedicating efforts to estimating the benefits and costs of integrating distributed generators into the power systems. In this context, this paper presents a Monte Carlo-based methodology that obtains the marginal costs of grid reinforcement for a Brazilian distribution utility, i.e., how much the installation of 1 kWp of rooftop PV costs. It is shown that the order the PVs are installed strongly affects the marginal cost and that a small part of the circuits is responsible for most reinforcement costs. Utilities and regulatory agencies can adopt this method to perform similar estimations.