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String vs Micro Inverters: Which type is better?

string vs micro solar panelSolar energy has become increasingly popular over the past few years. Many businesses and homeowners have had solar panels installed on their roofs in order to generate electricity to power their buildings. People have been attracted to solar energy due to its economical and environmental benefits.

What is solar energy? Solar energy converts the energy emitted from sunlight into electricity that can power a home or business. This alternative technology has been around since the 1950’s. However, with rising fuel costs and economies collapsing all over the world, people are wondering how using solar energy will benefit them.

Homes and businesses that use solar energy have solar panels installed on the roofs of their building. The panels attract the sunlight and then transfers the energy from the sun into ways to energize the building.

What happens is, sunlight shines down upon these panels and the energy converts to a direct current, or DC electricity. Energy for lights and electronics are converted into alternating current, or AC electricity.

In order to convert direct current into alternating current, you need an inverter.

There are two types of inverters: String Inverters and Micro-Inverters.

String Inverters

These inverters combine any number of “strings” of panels that are wired serially, and convert the electricity from DC to AC.  The strings typically include up to 11 panels each.

What String Inverters do is convert the sum of the generated direct current electricity, and convert it to alternating current electricity. If your home or business has a transformerless inverter, an array of panels can be installed at various orientations and tilts without effecting the panel output.

Many individuals have been confused by the difference between string inverters and a central inverter. String inverters are typically ideal for residences. In some cases, a central inverter might be more appropriate for a large 200 or 500 kW system used to power up larger business applications.

Micro-Inverters

As the name entails, these inverters are quite small, and are installed directly onto individual panels. These Micro-Inverters convert the direct currently electricity, at the panel, into alternating current electricity. At that point, the panels’ individual alternating current is combined and fed into your business or home.

Micro-Inverters are fairly new. While these inverters have been tested in the field, they have tested poorly. The increase in the number of potential points of failure compared to string inverters can be a design consideration given the higher incidence of failure.

Some companies have found themselves replacing micro-inverters about once a week, which is a burden on both the companies and the customer. While the micro inverters have warranties, the administrative nuisance and downtime become problematic.

Also, Micro-Inverters are less efficient. There are claims that suggest that micro-inverters generate an extra 5% output, even in shady areas. If these claims are true, that is still about 3% less than what string inverters give out.

In a string inverter, if a panel in a “string” begins to fail, a bypass diode that is already built into a panel can troubleshoot the problem, without affecting other panels that the string is connected to (this goes for any brand of solar panels).

If the string inverter does fail, it is much easier (and faster) to change out a string than a micro inverter.

Micro-Inverters do have a very lengthy warranty, however. Micro-Inverters have a 25 year warranty, whereas the String Inverter only has a 10 year warranty.

String vs. micro inverters: what should you choose?

Micro-inverters have been shown to be less efficient and costly, so the long term potential is questionable. If you are looking for an inverter that is efficient and cost-effective, you will want to go with a string inverter. The string inverter has proven itself time and time again. If one string fails, it is very simple to fix. With a bypass diode already built into the inverter, solar energy can bypass that specific panel and use the working panels to power your home and business. For a no-fuss inverter, you will want to go with a string inverter.

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