Flow reversal is a topic that is currently being debated a lot in the photovoltaic segment. And to avoid problems like this, it is necessary to have the right product, which meets the requirements with reliability and safety for the customer.
Among the equipment available on the market is the 7,5 kW inverter from Sofar – which has a complete line of solutions. Yghor Corrêa, Key Manager for the company in Brazil, highlighted that it is a robust solution with input currents compatible with most 18 A modules and has been on the market for many years in Brazil.
“Today, in its newest generation (7,5 KTLM G3 – BR) and with 70% overload, the model has become the ideal product for use in installations that need to meet this power requirement of up to 7,5 kW,” he said.
The manufacturer also has export control across its entire line, from the single-phase family to the largest inverters, which makes it possible to use any inverter performing grid zero and, consequently, meeting the requirement of not injecting energy into the grid.
“Using grid zero is very simple, requiring only a current transformer or a smart meter (depending on the inverter model used), connected to the inverter via RS485. All control is done by the equipment itself – which will receive information from the meter or current transformer and automatically make the necessary adjustments so that there is no energy export, only local consumption”, explained Corrêa.
How does flow reversal occur?
According to him, flow inversion occurs when electrical energy flows in the opposite direction to which it was designed to flow, that is, when instead of flowing from generators (power plants) to loads (consumer units) the flow occurs in the opposite direction.
“Inversion can occur for several reasons, but relating the phenomenon to distributed generation, it normally occurs when there is high local generation (a neighborhood with high installed solar power, for example) and there are no loads consuming this energy, thus causing it to make the opposite path in the distribution network,” he reported.
“This phenomenon can negatively impact the electrical grid, as in addition to affecting some protection and control equipment, it can generate the need to adapt the grid to deal with this flow,” added the Key Manager.
Currently, some energy companies are already denying the connection of new photovoltaic systems in specific regions, where it is alleged that there is no longer the possibility of new connections without flow inversion occurring.
“To provide alternatives, the ANEEL published in Normative Resolution No. 1.098/2024, which amends the former No. 1.000/2021, with three scenarios in which the flow inversion study does not need to be carried out, and the connection can happen normally, as long as it meets the requirements”, he commented.
The first of these, according to the expert, is when the system to be installed has a power in kW equal to or less than 7,5 kW, thus dispensing with the reverse flow analysis as it has power within the stipulated value.
The second is when the system does not inject energy into the distribution network. These systems are also known as grid zero or systems with export control, and since there is no energy being injected, there is no need for a flow inversion study.
“The last option is to adjust the system’s power so that it is compatible with the consumption of the location where the system is being installed. Resolution No. 1.098/2024 itself provides a formula and some constants, which may vary according to the customer’s profile, and are used to calculate whether the system’s power and energy consumption are compatible so that there is no risk of reverse flow,” concluded Yghor Corrêa.
About Sofar
In 2024, Sofar will celebrate the milestone of half a million inverters sold in Brazil, consolidating its position as one of the global leaders in photovoltaic solutions and energy storage. The company has currently shipped more than 31 GW of inverters globally.
In Brazil, the company has more than 20 partner distributors and an office with a showroom on Avenida Paulista, in São Paulo. This space not only offers practical training, but also presents new technologies to partners and customers, reinforcing the commitment to innovation and continuous development of the sector.
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An answer
Dear sirs,
I see no mystery regarding the very simple solution to this notorious flow reversal that is so controversial. Any installation that has a general feeder that followed standard 5410 for its dimensioning, i.e. voltage drop, short-circuit current and the corresponding minimum cross-section, will technically have no problems. In addition, we have had the already exhausted methodology for protecting electrical circuits with regard to their coordination and selectivity for a long time. In the specific case of flow reversal, there are the so-called directional relays, as the name suggests, i.e., they prevent a power flow to the utility grid. Engineer, professor, master in electrical engineering sciences, designer in photovoltaic generation, energy efficiency and electric vehicle charging station. Whatspp (21) 997716277