Solar Inverter

Solar Inverters

One important solar consideration is the usage of inverters, which work to convert solar energy.

Solar panels generate power from sunlight: this form of energy is called direct current (DC).  Solar panel inverters convert this DC into alternating current form (AC). AC form is the type of electricity that we use in our homes through AC outlets provided by the electric utility. The conversion of all the panels can occur at each specific solar panel (micro-inverters), or centrally through all the panels (string inverters).

One type is not inherently better than the other – they are just different ways of accomplishing the same thing. However, one may be better suited to your specific situation than the other.  One other device, called the power optimizer, is commonly used in a string optimizer-based system. The power optimizers provide functionality that is inherent to micro inverters.

Since a solar panel inverter converts energy from one form to another, there will be a loss of energy in the process. The efficiency rating will provide this value. Today, the gap in the efficiencies of the micro vs. string inverters is mostly negligible.

For technical reasons and regarding some solar panels, only the string inverter can be used (today). For example, panels with 72 or 96 cells need a string inverter since most microinverters today support only 60 cell panels.

Microinverters combined with string inverters coupled with power optimizer options are about the same from a cost perspective.

Micro Inverters

Most microinverters connect to one solar panel, although some can connect to more than one panel.  The microinverter takes the DC output from the solar panel as its input and then outputs the AC form.  The AC outputs of each microinverter are connected close to the panels, and a single set of AC wires are routed to the cut-off switch at ground level.

The major advantages of microinverters are: 1) The variance in the outputs of any of the individual solar panels does not negatively impact the system as a whole. If any one or more solar panels are shaded, facing different directions, or not functioning at all, the system will continue to function as a whole. The output will be degraded only by the amount of the lower functioning panels. 2) The failure of any microinverters will not affect the functioning of the whole system. The failed inverter can be replaced when convenient. 3) The system can easily be expanded, and different panels and microinverters can be utilized in the system. 4) The health and output of each panel can be monitored and reported on an individual basis. 5) Microinverters are integrated into the solar panel module for easier and speedier installation.

Microinverters work with many (but not all) solar panels based on their technical specifications.  For example, many microinverters do not support 72 or 96 cell panels (string inverters need to be used in these cases).  Also, individual microinverters have a limit on their AC output. Thus, regardless of the solar panels’ maximum output, the micro-inverter will only output its maximum limit. This limit may be less than the panels.

String Inverters

The DC outputs of all solar panels are connected to a standard set of wires on the roof and then routed to the DC cut-off switch at ground level.  From the DC cut-off switch, the DC is input into the central string inverter that in turn outputs AC.  String inverters got their name because each string inverter is connected to a grouping of panels called a “string.”

The major advantages of string inverters are: 1) String inverters work with almost all solar panels, except those with integrated microinverters. 2) High wattage panels can be taken advantage of by using appropriately higher output string inverters or multiple string inverters. 3) Servicing the string inverter will not require working on the roof. 4) String inverters have been in use for solar since the beginning and are generally cheaper (not including the power optimizers) than micro-inverters.

A string inverter’s maximum output is affected by the least performing solar panel. This makes it non-ideal for use when there is shading, as some panels in a string may cause an issue.  Since string inverters are central, when a string inverter fails, the whole system fails.  Without the use of power optimizers, string inverters cannot monitor and report on health and production on an individual panel basis.  String inverters have certain technical conditions that make the design process a little more complicated than in the case of microinverters.

Power Optimizers

Power optimizers take the DC from the solar panels and provide an optimized DC output. The output is then fed into a string inverter.  Power optimizers were developed to address some of the shortcomings of string inverters. Power optimizers address shortages like the marginal performance of some panels affecting the whole system, and per panel monitoring.  Although power optimizers are cheaper than microinverters, one power optimizer is required for each panel in addition to the string inverter. This makes the total system cost about the same.

Smart Modules/Panels

Some manufacturers are integrating microinverters with the solar panel.  This makes the design and installation process easier, quicker, and cheaper. However, this process does come at the cost of reduced design flexibility.

We carry the highest quality microinverters, string inverters, power optimizers, and smart module solutions. We use our top-tier products to design a system based entirely on your needs.  Some of our partners include Chilicon Power, Enphase Energy, SMA, SolarEdge, and SunPower.

SolarEdge inverters are among the most popular and high-quality solar power inverters. They have an excellent reputation for reliability. Enphase microinverters are perfect in case there is shading from trees or buildings, as the panels work independently from each other. The Enphase system is never going to fail, even if the Enphase microinverter fails.



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