How does a PV system work?

How does a PV system work?

20More and more Portuguese companies are installing a PV system on their roofs. The generation of energy through the sun is a profitable and ecological solution. With a self-consumption solar power plant you can reduce electricity costs and be more independent from large energy suppliers. But how exactly does a PV system work?

The photovoltaic system uses the energy from the sun to convert it into electricity. So just install solar modules on the roof, turn them on and off? It’s not as simple as that. We explain in this article how a photovoltaic system generates electricity for local self-consumption or for injection into the public grid.

What are the components of a PV system?

PV systems do not need many components to generate electricity – basically, PV modules do all the work. As soon as the sun shines, they absorb the radiation and convert it into electrical energy, producing a direct current (DC). However, direct current is not used to be consumed directly on site or to be injected into the public grid. To do this, it must first be converted into alternating current (AC).

The inverter has the task of transforming direct current into alternating current. After this conversion, all the energy can be used locally or injected into the public grid. The direct current, generated by the photovoltaic modules, is conducted to the inverter with the help of solar cables, and is distributed (in AC) by the customer’s switchboard, or directly on the grid connection.

If there is a surplus of solar energy, which is not consumed directly, it can be stored for later consumption. The equipment used for storage are the solar batteries whose price has been decreasing, are a good solution, increasing self-consumption.

The basic functioning of a PV system:

• PV modules convert solar radiation into electricity (direct current).
• The direct current is conducted from the module to the inverter via solar cables.
• The inverter converts direct current into alternating current so that it can be consumed directly,
  stored in a solar battery or fed into the public grid.

Modules with monocrystalline or polycrystalline cells

Solar modules are the heart of the photovoltaic plant. The offer from manufacturers and models is great. New modules are regularly advertised, more and more effective. The solar modules are produced from crystalline cells, which produce direct current when exposed to sunlight.

For the production of crystalline solar cells, quartz sand silicon is used in particular. Polycrystalline silicon consists of a myriad of silicon crystals of different sizes. Monocrystalline silicon, on the other hand, requires a higher degree of purity of the silicon, and consists of a single large-size silicon crystal.

PV modules with polycrystalline solar cells have been very popular for a long time as they were easy to manufacture and profitable. However, today most manufacturers produce monocrystalline solar cell modules at very affordable prices. Monocrystalline modules have a higher power, for the same area, and stand out aesthetically by their dark and uniform colour.

The inverter is the brain of the PV system

The electrical grid in Portugal, as in most countries, is based on alternating current. Therefore, as mentioned above, the electricity generated by the solar modules must first be converted through an equipment called an inverter.

In addition to the DC / AC conversion, the inverter monitors the parameters of the solar production and the electrical grid, regulating itself and allowing both self-consumption by the customer and the injection of the excess production into the public grid. In case of any disturbances in the public grid, the inverter immediately disconnects the solar system from the grid, thus protecting the photovoltaic system itself, namely from possible overvoltages, as well as goods and people.

As well as grid photovoltaic inverters, there are also inverters that can be used to charge solar batteries (hybrid inverters). The solar batteries store direct current, and the inverter provides the management using direct current to charge the batteries, converting it into alternating current when it is necessary to consume that energy, thus minimizing energy losses and increasing the yield of the system.

Transporting the sun’s energy: The solar cables

As we have previously mentioned, the electricity originally produced is transported with the help of solar cables. These (solar) cables are directly connected to the modules and, in turn, to the inverter, ensuring the possibility of using the energy produced in the modules.

It is not possible to use just any cable. The solar cable must meet special requirements: it must always guarantee optimum insulation (since they are subject to voltages that can easily reach 1,500 V); and be resistant to adverse weather and UV rays. It is very crucial to adjust the diameter of the solar cable according to its length in order to minimize energy losses during transportation.

Increase self-consumption with solar batteries

A self-consumption PV system with solar batteries allows you to consume solar energy during the day, at night or even when the sky is cloudy. The stored solar energy remains available in the solar battery until it is consumed. Thus, solar energy consumption is maximized and the grid’s autonomy can be increased: this translates into a significant reduction of the electric costs.

PV systems for companies without investment

PV systems allow the generation of solar energy for self-consumption and/or for injection into the public grid. Currently in Portugal, you can choose the UPAC scheme (self-consumption), with or without injection into the grid and the UPP scheme that only injects into the grid.

SOLVasto’s financial model allows to obtain an UPAC (self-consumption) PV system without investment. Through our investor partners you can start saving immediately. The investor takes responsibility for the ownership and management of the project, guaranteeing the client the excellence of the performance of the equipment, and consequently, its profitability without any risk on the installation. The rents that are owed by the client to the investor are below the savings generated. At the end of the contract term, the installation is the client’s, at no extra cost, and the income it continues to generate reverts entirely to the client. However, the customer always has the option to purchase the installation, throughout the contract, and remains independent in the choice of its grid energy supplier.

Do you want to invest in an UPAC or UPP photovoltaic system to produce “green energy” in your company? SOLVasto develops profitable turnkey PV projects and takes care of them ensuring the best performance for many years. Contact us.