Microinverters vs String Inverters – Which is Best for Your Solar Project?

For all the benefits of solar energy for your home, there has always been one key challenge – Solar panels produce direct current (DC) power while your house runs on alternating current (AC) power. 

For that reason, every solar system needs to have an inverter to convert the DC power the system produces into AC power that your house and the grid can actually use.

But there are different types of inverters so in this article we’re going to compare microinverters vs string inverters. We’ll walk you through the pros and cons of each type of set-up to help you decide with your solar installer which is best for your home

For most of the solar industry’s history, string inverters have been the preferred choice, largely because they have historically been the less expensive option, more reliable and easier to fix if they did go wrong. 

But in recent years, as costs have come down and reliability has improved, microinverters have come into their own and there is now a real decision to be made as to which is the best for each individual installation.

Pros and Cons of String Inverters

The biggest advantage of string inverters is their simplicity. More often than not, if a solar system malfunctions, it’s because of the inverter. String inverters are easy to troubleshoot and repair because there’s just one to deal with. You don’t have to check dozens of individual inverters to pinpoint where the problem lies.

A string inverter is typically installed close to your main service panel or your  electric meter and for a typical Cape Cod home, one inverter would likely be enough to connect to all of the panels. For larger systems, there may be more than one inverter and each would be connected to its own string of panels.

Most importantly, though, whether it’s one inverter or several, they are connected to the panels in series – just like the lights on a Christmas tree. This makes it both time and cost-effective to set up a simple system and the inverter is easy to fix or replace if anything goes wrong, because nobody has to go up on the roof.

But there’s a big drawback to setting up a solar system in series like this. It means the entire system’s power is capped to the level of the lowest performing panel. So if just one panel gets shaded or covered with debris, it can drag down the energy production of the whole string. 

And if one panel were to malfunction and stop producing any power at all, then, just like a row of Christmas tree lights, the entire string will stop producing electricity.

For that reason, string inverter set-ups are not the best solution for homes that are shaded by trees, or for sections of roof where dormers or other roof obstructions can block out the sun for larger portions of the day. 

Since this describes a lot of homes on Cape Cod, it’s good that microinverters have come down in cost recently.

Pros and Cons of Microinverters

The great advantage of microinverters vs. string inverters is that they can help to eliminate this problem because, rather than being connected in series to several panels, each panel has its own individual micro inverter connected to the back. Some models of microinverter allow for two or four panels to attach to each unit while some more  modern panels have the microinverter integrated into the panel itself, which eliminates a large part of the installation work.

Micorinverters solve the problem of electrical bottlenecking that you see with string inverters. Should one panel get shaded or stop working, the others keep on producing power so your system’s total production drops just by what you lose from that one faulty panel. 

Microinverters also don’t require additional equipment to meet electrical code requirements, while string inverters have to be paired with DC optimizers in order to meet code.

What Are Power Optimizers?

Power optimizers allow string inverter set-ups to offer some of the benefits of microinverters. 

Like microinverters, power optimizers include a dedicated optimizer for each panel, known as the module-level power electronics (MLPE). 

But unlike microinverters, optimizers don’t convert DC power to AC, they merely optimize the DC current and forward it to a central string inverter for conversion. If your roof gets some shade throughout the day, you’ll likely see better efficiency from your system with power optimizers. Like their microinverter cousins, power optimizers lessen shading’s effects on overall performance and allow for the monitoring of each individual panel’s output.

Microinverters vs. String Inverters: Which Should You Choose for Your Solar Project?

Choosing the best inverter really boils down to your project’s specifics and how your installation is planned out.

If you’ve got a residential project with a straightforward roof layout, with all panels on one side of your house and minimal shading concerns, we’d suggest opting for a string inverter coupled with DC optimizers. The optimizers boost each panel’s energy output while maintaining the simplicity of managing just one inverter — not to mention it’s more cost-effective.

On the flip side, microinverters are ideal if you’re dealing with a complex system setup – say, having panels spread across multiple sections of a roof. Or a system that might need to be expanded at a later date.

Plus,microinverters  shine when it comes to handling shaded areas during different times of the day. Sure, they might add a bit extra to your upfront costs but they offset that by offering long-term gains from squeezing out peak performance from every single panel.

If you’d like an informative, no-pressure chat with either of the Cape Cod Solar Guys, you can contact us here.

Microinverters also don’t require additional equipment to meet electrical code requirements, while string inverters have to be paired with DC optimizers in order to meet code.