According to a study According to a study published by Wood Mackenzie, annual spending on solar plant repairs and maintenance is expected to grow to $9 billion by 2025. Of this total, Asia s for $4,1 billion, Europe, the Middle East and Africa for $3,5 billion, and the Americas for $1,8 billion.
Due to this scenario, retrofitting a solar plant, which consists of modernizing, recovering, and repowering a piece of equipment or set, is increasingly being adopted by consumers to revitalize the facilities.
In Brazil, for example, there are several cases in which customers need to exchange products. In Campinas (SP), the solar plant of TMW Energy, which belongs to the Brazilian group Royal FIC, is operating normally and with productivity gains.
The company replaced the 21 inverters, which were experiencing problems, with 250 kW Canadian Solar models. In total, the project achieved an increase of 6% to 15% in generation performance.
Investment in solar energy to bring more savings has also been increasingly present in the hotel segment. And when the photovoltaic source is integrated with energy storage through batteries, the great benefit is precisely the electrical supply at times when solar production is scarce or non-existent, such as at night or on cloudy days.
This is the case of the EcoParque das Aves bubble hotel, located in Botucatu (SP). The space has an on-grid retrofit system from PHB Solar, installed in a carport structure.
We can mention several successful cases that invested in retrofitting and are achieving good financial results and also energy autonomy. In addition to those mentioned above, there is a project that was recently installed in São Francisco Xavier, a district of São José dos Campos, which is part of the Metropolitan Region of Vale do Paraíba and Litoral Norte, in the interior of São Paulo.
The old off-grid plant, built for a rural producer at the top of Serra da Mantiqueira in January 2017, was transformed into a hybrid plant, installed in December 2023 to serve local residences.
According to Lucas Trettel, engineering manager at Solbell Energia Solar, the integrating company responsible for the project, the inverters and battery bank were replaced, while maintaining the same photovoltaic modules.
The 5 kWp solar plant has 20 250 W s from Resun Solar, which generate 600 kWh/month, a 5 kW inverter from Deye and two 48 V and 100 Ah lithium batteries from Unipower.
In total, R$48 was invested in the project, which is providing, on average, savings of R$530 per month for the end customer. The payback period is approximately six years.
In this project, even though it is simple in of system size and installed power, it is possible to observe some very interesting points related to the change and evolution of technologies.
About inverters
Initially, two 2,5 kW off-grid inverters were installed on site. These products were replaced by a single 5 kW hybrid inverter, maintaining the nominal power of the system and occupying practically the same space as a single off-grid inverter.
Read also Off-grid system: how does it work?
“With the hybrid system, we are now able to generate savings for the customer by reducing their energy bill – by injecting excess electricity generated by the system into the grid after fully charging the battery bank,” explained the engineer.
“Previously, the inverters would stop operating and limit the energy generation of the photovoltaic modules at times when there was no consumption and the batteries were charged,” he reported.
According to him, it is also possible to observe the evolution of electronics. In addition to the significant reduction in the size of the components, the new equipment has several other functionalities, such as the ability to work in on-grid mode and an intuitive and playful HMI for the end .
In addition, it has a remote monitoring system, high input DC voltage amplitude – eliminating the need for external parallel association of modules – and GEN input – which allows integration with other power generation systems such as gas and diesel generators, among others.
About batteries
The installation had a set of lead-acid batteries consisting of 20 12 V and 40 Ah batteries capable of storing 9,6 kWh of energy. These equipment reached the end of their useful life and were replaced by two 4 V and 48 Ah LiFe-Po100 batteries, ensuring the same energy storage capacity of 9,6 kWh.
“The difference in storage capacity of a lithium battery compared to a lead-acid battery is impressive, and the reduction in space is clear to see. Currently, with lithium batteries we are using only about 5% of the space that was previously used with lead-acid batteries,” said Trettel.
“In addition, the depth of discharge is one of the main advantages of lithium batteries. We can work with up to 90%, while lead-acid batteries are recommended to be charged at only 20% to reach their expected useful life,” he highlighted.
This difference in depth of discharge between lithium and lead batteries makes all the difference, as it is possible to increase the useful storage capacity of the system, even if the nominal capacity of the battery banks is the same.
In the case of lead-acid batteries, the autonomy was 1,92 kWh (20% of 9,6 kWh – nominal capacity of the bank). With lithium batteries, the autonomy increased to 8,64 kWh (90% of the same 9,6 kWh), that is, by changing the battery bank it was possible to increase the customer's autonomy by 4,5 times.
About photovoltaic modules
Solbell's engineering manager also spoke about the speed of evolution of technology embedded in solar s, something that the sector follows closely.
“At events like Intersolar, we see increasingly powerful and efficient modules arriving in Brazil every year. However, an important characteristic of these s is their long lifespan, with performances of up to 30 years guaranteed by manufacturers. Currently, modules with powers close to 700 Wp are already being sold,” he stressed.
“Therefore, it was expected that the 20 250 Wp s installed in this project in 2017 would be fully operational, eliminating the need for updates. In this case, all that was done was to redistribute the modules in the MPPTs of the new inverter and add the necessary protections,” he concluded.
Project execution
The photovoltaic project, located in the district of São José dos Campos, was dimensioned, designed and executed by engineers Lucas Trettel, Alberto Sobrinho and Guilherme Maioni from Solbell Energia Solar.
Report published in 24nd edition of the Magazine Canal Solar
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