Second only to the solar panels themselves, the most important part of any residential solar energy system is the inverters. They are necessary for converting energy generated by solar panels into usable electrical power that can be utilized by home appliances and devices. Without inverters, solar power could never support the electrical needs of a modern home. That is why it is critical for homeowners to carefully consider their options when choosing inverters and to become well-informed about choices. Below is more information on solar inverter options and what you should know about them:

Central versus micro

One of the biggest decisions you will need to make when choosing a solar inverter is whether to purchase a central inverter or micro-inverters. Here is an explanation of each type:

  • Central inverter - Sometimes called a string inverter, the central inverter is the traditional inverter style used for residential solar energy systems. The main characteristic of central inverters is that they chain together the electrical feed from each individual panel. Central inverters are less expensive than micro-inverters, and they are reliable, effective devices when used in areas where shading of panels is not a consideration. However, central inverters are susceptible to bottlenecking, a phenomenon that exists whenever one panel is receiving less energy than others. That means the inverter will only function at the lowest incoming level of power; no matter how much energy is available from other panels, the shaded panel will create a bottleneck in the string of power and lessen the available electricity for the inverter to use.

  • Micro-inverter - A newer technology, micro-inverters are much smaller cousins of the central inverter. Instead of having one inverter through which all power flows, micro-inverters collect power from each panel independently and then distribute it into the home. Micro-inverters offer a huge advantage over central inverters by eliminating the possibility of bottlenecking; instead of lowering power availability, micro-inverters operate on the basis of one panel apiece and this maximizes the availability of a system's overall output. The only disadvantage of micro-inverters when compared to central inverters is their higher cost.

Waveform type

The waveform type is a measure of how inverters convert incoming direct current (DC) to outgoing alternating current (AC). When looking at AC power visualized on a screen, the waveform is the up-and-down oscillating line that demonstrates how "smoothly" the power moves out of the inverter. The waveform generated by inverters can take one of three kinds:

  • Square waveform - The crudest kind of waveform, square waveforms are choppy representations of how AC power is produced by inverters. Power produced by a square waveform inverter can cause damage to some electrical devices, due to its abrupt on-off cycling. This makes square waveforms less suitable for use in homes than other waveform types.

  • Modified sine waveform - A step above square waveforms, modified sine waveform inverters provide a smoother power output that is less problematic for some home electrical appliances. However, sophisticated electrical and electronic devices may not function properly with modified sine waveform power, and that makes these inverters less suitable for many homes.

  • Sine waveform - The top-of-the-line inverter waveform type, sine waveforms generate a smooth curve of AC output and are suitable for all home electronics and electrical devices. They are also the most expensive, but if you use demanding devices that require power "purity", then a sine waveform inverter is the best choice for you.

Grid-tie capability

For stand-alone solar power systems, inverters are not connected to the wider power grid, which increases their simplicity of function and lessens their cost as a consequence. However, if you intend to maintain your connection to the electrical grid, then your inverter will need to have grid-tie capability. The following attributes must be in place for grid-tie capability:

  • Synchronization with grid frequency - Power systems in the United States use 60 Hz as their standard, and any inverter that is connected to the grid must also be in conformity with the 60 Hz power standard.

  • Automatic disconnection - In the event of a grid failure, grid-tie inverters must immediately be able to detect the loss of power and disconnect themselves from the grid. Otherwise, they may continue to push power into the grid and potentially injure unaware electrical workers who believe the line is dead.

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