Smart generation and consumption: technologies to increase financial return

Home automation is a hot topic. Voice assistants on your cell phone are already capable of turning lights on and off, programming the air conditioning temperature while you are traveling to your home, as well as controlling sunshields, smart locks, sound and monitoring systems.

Therefore, it is expected that the photovoltaic system will integrate into this ecosystem and enrich the final user experience.

Photovoltaic systems and smart consumption

Photovoltaic inverters can be seen as the heart of the photovoltaic system. They convert, monitor and deliver energy, therefore, the automation possibilities are concentrated there.

In order for the inverter to make decisions about how to act and where to act, there must be internal programming that is fed by a set of sensors and that will decide which actuators to activate.

Each manufacturer has a set of specific sensors for their equipment, however, it is common to find smart energy meters close to the connection point to the grid.

These devices work by measuring the amount of energy consumed in the enterprise and injected into the public grid, in a similar way to the bidirectional meter, with the aim of informing the inverter about the energy situation of the system as a whole at each moment.

With information on the amount of energy being generated and injected, it is possible to estimate the instantaneous consumption of the enterprise.

The inverter, armed with this information, will be able to activate some loads such as the resistance of a boiler, charging batteries and electric cars, for example, at times when the energy generated is greater than that consumed by the enterprise.

In this way, the energy that would be surplus and injected into the public energy network is then consumed in the consumer unit.

As in some states ICMS in a portion of the injected energy, the profitability of the photovoltaic system will be improved.

This alternative becomes even more attractive if the current energy compensation rules (defined in Normative Resolution No. 482) are changed, since in the proposals of the ANEEL (National Electric Energy Agency) would decrease the energy compensation percentage of the energy (as will be explored later in this article).

This activation of loads can happen either digitally through the device's ports, wirelessly or even directly integrated into the inverters, as in the case of hybrid models and models with a built-in vehicle charger.

There are already several manufacturers on the market with inverters that allow this communication and device operation.

ICMS, new rules and financial impact

The energy bill is made up of a portion referring to the energy itself, called TE, and a portion referring to the use of the network, called TUSD.

In some states, such as SP, RJ, RS and ES, the excess energy generation exported to the grid has a decrease in its financial value, as the ICMS of the TUSD portion is charged on it.

Example

Table 1: Monthly invoice with Light tariffs in RJ, ICMS is charged on the TUSD portion of energy injected into the public grid

An intelligent system increases consumption along with the load, reducing the need for energy supplied by the concessionaire and also reducing the amount of energy injected, therefore, minimizing the impact of ICMS charges on TUSD.

The table below exemplifies this impact by simulating a load that consumes 200 kWh/month being consumed outside system generation hours and during system generation hours;

Table 2: Energy bill, now using the drive solution. Cost reduction estimated at R$ 31,64

As mentioned earlier, if the new proposal from ANEEL for the compensation of energy credits, the energy injected into the public grid will not be fully compensated (understand more details in our article: Impacts of the change to RN 482 – distributed generation rules).

In table 3, a simulation of energy costs is made taking into account alternative 2 proposed by ANEEL, in which the energy injected into the grid would have a 34% discount on the total injected energy tariff.

Table 3: Example energy bill, simulating alternative 2 of the proposed revision of the ANEEL

By avoiding the injection of energy into the grid and consumption alongside the load, the impact of the proposed new regulation is reduced.

In this case, a load that consumes 200 kWh/month is also being considered and is consumed outside of system generation hours and during system generation hours, and the results can be seen in Table 4.

Table 4: Energy bill according to the proposed review of ANEEL, in Alternative 2. The impact on energy compensation causes the consumption profiles to have a greater difference in values. With smart consumption, the cost reduction is R$90,04

The smart meter costs around R$2000 already with installation, an amount easily justified by the benefit it provides, as in the example, where the annual savings reach R$1080.

Hybrid battery systems are also an alternative to increase the energy independence of the enterprise and minimize the energy injected into the grid, especially in those cases where it is not possible to control load consumption.

In this type of system, the battery would receive the instantaneous surplus energy and return it in moments where the smart meter indicates that solar generation is not capable of supplying all the necessary energy.