GENERAL INFORMATION ABOUT PV SOLAR SYSTEM
What is a solar PV system?
A solar PV panel produces current thanks to the physical characteristics of the semiconducting materials of its cells (each cell measuring 10 by 10cm, up to 15 by 15cm), when exposed to sunlight. Each solar panel is composed of a set of cells (usually 36 or 72 cells) that are connected together in series and parallel; they were initially designed to charge 12V/24V batteries for off-grid application and the design remains almost unchanged since then.
Composition of a solar PV panel
More broadly, a solar PV system is composed of the following components:
- The solar panels: it produces DC current (the more irradiation it gets, the higher its output current). Only one sort of solar panel is proposed to be installed here for all the roofs. Solar panels are mounted on an aluminum structure; the latter is fixed on the rafters with specific roof screws, replacing the old and corroded one. Solar panels are connected in series to form a string; several strings are connected in parallel to form an array, into an array box (also called DC box). Due to this connection, if only a small part of a solar panel is shaded, it will affect the output of a whole solar array.
- The inverters transform DC current into AC current, by synchronizing to the local power supply. In case of power shortage, or events of voltage/frequency, the inverters will automatically stop producing, complying with the German standards DIN VDE 0126.1.1. It cannot produce power without access to EVN grid (or diesel production), as it has no battery storage.
- The solar system is usually designed without battery and will not power a building or a given utility. PV systems with battery storage do exist, but they have a highest investment cost together with a higher maintenance cost.
- Electrical boxes in DC and AC sides will provide metering, lightning protections and all necessary electrical switches.
- A whole monitoring station will keep tracks of the operating conditions of the solar system (irradiation level, temperature of solar cells and ambient temperature) and will record alarms, output powers (current and voltage), grid status.
Snapshot of a typical monitoring system (Schneider Vietnam)
The diagram below shows the different components of a typical rooftop grid-connected PV system:
Architecture of a typical grid-tied solar PV system (source: ARTELIA Vietnam)
As an example, below a PV system installed on the canopy in a supermarket in Binh Duong, Vietnam
Solar PV system in Big C Di An, Binh Duong (Photo: ARTELIA Vietnam)