In the electrifying world of solar energy, the sun’s rays hold the power to transform sunlight into electricity. When delving into solar panels, it’s essential to illuminate a fundamental concept: the distinction between AC and DC currents. Like the yin and yang of the electrical universe, these two currents play a pivotal role in shaping the efficiency and functionality of solar power systems. It is crucial to understand this difference in the solar panel industry because solar panels generate DC electricity, but the electricity used in most homes and businesses is AC.
We explain the terms AC and DC current and explore the distinctions between them, aiding understanding of their relevance to solar panels and other solar electricity systems.
Alternating current (AC) is the most used and most-preferred electric power for household appliances, such as fridges and washing machines, as well as for equipment in offices and other buildings. In AC current, the electric charge flow changes its direction intermittently and can be identified in a waveform (sine wave); this basically means it can be visualised as curved lines. These curved lines represent electric cycles and are measured per second. The measurement is read as Hertz (Hz). AC is the preferred current in powerhouses, homes, and offices because generating and transporting AC current across long distances is reasonably easy.
DC stands for direct current. Unlike alternating current, the flow of direct current does not change periodically (i.e. there are no waves). Instead, DC travels in a single direction in a steady voltage. DC is most often used to supply power to electrical devices and to charge batteries. For example, electric vehicles and mobile phone batteries – basically anything that runs on a battery and uses an AC adapter while plugging into a wall or uses a USB cable for power relies on direct current.
Solar panels absorb solar energy and use this to generate direct current (DC) power. However, every solar panel system will include an inverter which is the vital component which converts DC electricity into alternating current (AC) – this is the type of power the electrical grid uses to power our homes.
Let’s explore the distinctions between AC and DC power in more detail:
Direction of current
AC: The direction of the electric current periodically reverses, moving back and forth. This reversal occurs at regular intervals, usually 50 or 60 times per second (measured in Hertz, Hz).
DC: The electric charge flows steadily in one direction without changing.
AC: Voltage levels can be easily transformed using transformers. This makes it more suitable for long-distance power transmission.
DC: Changing voltage levels in DC systems is more complex, requiring electronic components like inverters.
AC: Well-suited for long-distance power transmission due to the ability to change voltage levels efficiently.
DC: More efficient for shorter distances and certain applications like high-voltage direct current (HVDC) transmission.
AC: Difficult to store in batteries without converting it to DC first.
DC: Easily stored in batteries.
AC: Generally considered to be safer for power distribution over long distances and in homes because it can be easily transformed to different voltage levels.
DC: Often used in low-voltage applications and is commonly considered safer for small, localised systems.
Solar panels produce DC: Photovoltaic (PV) cells in solar panels generate direct current. This is because sunlight hitting the solar cells creates a flow of electrons in one direction.
AC is used in the grid: Most electrical appliances and the power grid itself operate on AC. Therefore, solar power systems need inverters to convert the DC electricity generated by solar panels into AC electricity for use in homes and businesses.
Grid-tied systems: In grid-tied solar power systems the generated DC power is converted to AC by inverters. This allows the electricity to be used locally and/or fed back into the grid.
Off-grid systems: In off-grid applications, such as remote locations without access to the power grid, DC electricity from solar panels can be stored in batteries for later use or converted to AC for specific appliances.
In summary, understanding the differences between AC and DC is crucial for designing efficient and safe solar power systems that integrate seamlessly with existing electrical infrastructure.