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Pros and Cons of String Inverters vs. Microinverters

Posted by James Bartley on Jul 8, 2019 5:54:31 PM

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What type of inverter are you going to use on your future solar install? There are three main types of inverters on the market all with there own sets of strengths and weakness's. First the micro-inverter, then the DC optimized system with a central inverter and then the central inverter also known as a string inverter.

The Microinverter is an inverter on a per panel basis, this converts each solar panels DC production into AC production that your house hold uses.

The String inverter is an inverter that converts the DC power from 6-10 solar panels on average inorder to create an elevated DC voltage that the central inverter can convert to AC power.

The advantages of string inverters

1. The Price is typically the lowest in comparison between the microinverter and the String inverter

The disadvantages of string inverters

1. The Per panel Monitoring is not possible unless you use a third party solar panel monitoring application like what tigo solar panels offer.

2. The Weak link syndrome, you are only as strong as your weakest solar panel in a string so if one goes out the whole string goes out.

3. Point of weakness when and if the string inverter fails this will leave your entire solar system off until the warranty or new inverter is taken care of rendering the customer in a state that affects the solar ROI.

4. Versatility, due to the need for 6-10 panels in a string you may be limited to the design of how you install solar on a roof that may be smaller and need to orientate the panels to the east or west in combination with the south.

5. Aesthetics, beauty is in the eye of the beholder but typically when we install a string inverter this means that you will have equipment on the side of your house or business, and in saying this sometimes that is not possible to get away from but some people would prefer the "look" of nothing by using microinverters which reside underneath each solar panel instead. 

6. Warranty is the smallest in the industry when comparing to microinverters.

Advantages of microinverters

1. You are able to see per panel monitoring which is great for the customer knowing if there is a problem with any one solar panel in the future you will know which one and exactly where it resides. Your solar provider will get an alert and have the ability to dive into the situation in a proactive state instead of a reactive state.

2. Each Panel/microinverter is always producing at the max capability and is not affected by any neighboring solar panels.

3. If one microinverter fails then you will not affect any other solar production in your system giving you a little more redundancy for producing at your optimum year round.

4. Design Versatility, with microinverters you are not limited to keeping the same orientation and or a miniumum per string in order to layout solar on your roof you can start with as little as one panel facing any orientation (besides north if you are in the northern hemisphere)

5. Warranties are typically 25 years vs the 5-10 year warranties of string inverters.

Disadvantages of microinverters

1. Price can be typically higher than string inverters but with the advent of what they call competition there will always be innovation and with saying that there are other brands of microinverters on the market today that are beginning to rival the cost of string inverters and at the same time still have the 25 year warranty.

2. Some would claim that with more parts and pieces to any puzzle there are more ways things in a system that can fail, but I believe that is really a strength more so than a weakness.

Opinion Speaking:

One thing I absolutely love about microinverters, as a solar installer with systems over 8 years working in the field, if one inverter fails, it does not cripple the entire system. Each solar panel with a micro-inverter will independently produce power at each panels max because all panels are not created equal and minor wattage fluctuations may be seen from within while watching a typical monitoring portal. 

Warranty... not to say that you cant get an extended warranty on string inverters, but it is typical to see a 25 years for most all micro-inverters and when investing in a product especially if you are financing through a 15 or 20 year solar loan then you want to make sure that A. the inverter's which are the heart of your system have a long hearty warranty and B. the installer that is installing your system is going to honor the warranties given. There is nothing wrong with a solar company that is putting down roots and just getting started. In fact you may even find a company that is made up of great people that just so happen to have left another solar company to start there own, as that is the typical evolution of how business begin. Consider the statistics from a book like E-Myth Revisited by Michael E Gerber, that 50% of most business fail within the first year and the remaining 50% fail within the first 5 years, so not trying to be too biased in this comment we were once at that point back in 09' but maybe look at the history and future of the company you are choosing before signing on the dotted line.