3 Inverter Tips for Designing Your Solar Array

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  • June 11, 2015
installing-racking1 **This article was featured on KSL. This week we sat down with Kelly Curtis, Director of Operations at Solaroo Energy, to discuss inverters. The second most important component to your solar array is your inverter. Solar panels produce electricity in direct current (DC), and the inverter is what will convert the DC into alternating current, or AC, which is what your house will consume. The inverter is the second most expensive component to your solar system, and can be vital to the efficiency and functionality of your solar array. 25615428

String Inverter vs. Micro Inverter

At a basic level, the difference between a string inverter and a micro inverter can be compared to old fashioned Christmas lights. A string inverter ties a group of panels together on a string, then connects to the string inverter, making it similar to a string of Christmas lights with regards to shading. When one panel is shaded, then all panels on the string act as if they were shaded in the same manner as Christmas lights – when one light goes out, the whole string is out. Micro inverters, however, are smaller inverters that are mounted to the back of each panel. They make each panel independent from each other with regards to shading. When one panel is shaded, the others are still producing. So you might ask, “Why use string inverters at all?” Curtis explains, “Even though micro inverters are more efficient when it comes to production, we still have about 30 – 40 percent of our customers that prefer string inverters because of the emergency power options. It almost comes down to personal preference.” Curtis gives us three tips when considering which inverter will help you meet your solar goals.

Emergency Power

If emergency power is a concern to you, then a string inverter may be the way to go. Solaroo Energy can install a string inverter that has daytime emergency power, at virtually no additional cost to the customer. In this case, a transfer switch is installed, and an outlet box that has roughly 1 5 amps of emergency power, when it is sunny and the system is producing. This stops short of installing expensive batteries, but at least provides a little emergency power, similar to a small generator. Many clients will forgo producing an extra 4-5 percent of power on an annual basis to have this option.

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Shading

Shading is important when deciding which inverter is best. Even a roof with no obvious obstacles will have some shading when the day begins, ends, and as clouds roll through the sky. Curtis recommends that you only consider a string inverter with an unobstructed roof. If there is some shading from trees, a neighbor’s house, or other obstacles, the drop in production with a string inverter might not make sense. There are hybrid string inverters that offer options to put power optimizers that act as mini micro inverters on the back of each panel, which will make each panel independent with regards to shading, but will limit your emergency power options. 25602587  

Warranty

The main manufacturer of micro inverters, Enphase, will warranty their micro inverters for 25 years, whereas string inverters can range from 10 years up to 25 years. Curtis remarks, “Some clients have a generator for emergency power, or they aren’t too concerned about grid failure. Others will easily sacrifice a little production for having access to their solar in the case of an emergency.” Whatever your preference, having an experienced solar consultant can make all the difference.