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Inverters

String versus Micro Which is the Right Choice?

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When it comes to making decisions about a PV system, one of the most common decisions a system owner has to make is whether to choose a micro inverter or a string inverter. Stephen Breheny is best placed to understand the difference between each of these products and technologies, and provide the product best suited to each specific application.

For system installs on tricky roof structures, or where sub-sections of a PV array need to be separated or installed on different orientations, a micro inverter can represent the simplest and lowest cost system. Since micro inverters are AC coupled and individually track their PV module’s maximum power point, they are more flexible in how and where they can be installed compared to DC coupled PV panels and a string inverter.

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Performance & Shading

Under normal unshaded conditions, a string inverter will typically offer the lowest cost and greatest energy yield. For varying degrees of partial shading of the PV array, a micro inverter can offer slightly higher performance (~1 – 4%).

Under normal un-shaded conditions, a correctly sized string inverter system will typically outperform a correctly sized micro inverter system by ~0.5%. Micro inverters are able to reduce some very small losses such as DC cabling and any module mismatch, but they have a lower operating efficiency. Put together, this means string inverter systems will typically outperform micro inverter systems in normal un-shaded conditions.