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What Are AC Solar Panels?

By Linda Pinkham

Tags: solar, electric system,

What are AC solar panels? I always thought solar panels had to be DC, but now I’m hearing about new AC products. How well do these work? Are there any benefits to using them?

AC (alternating current) solar panels are a promising new idea on the photovoltaic (PV) market. The panels themselves still produce DC (direct current), but each panel would come with its own attached micro-inverter, which converts the DC to AC. The inverters also synchronize the output with the grid, allowing the modules to be grid-intertied. The micro-inverters replace the need for the single, centralized inverter currently used in solar-electric systems.

AC solar panels with integrated micro-inverters are under development by several companies, but are not yet in widespread use, so there’s no performance data from the field. Bob-O Schultze of Electron Connection, an installing dealer in northern California and southern Oregon says, “No one that I’m aware of is marketing AC panels at this time. What is available is something called an Enphase inverter. These are designed for use with individual 24-volt (nominal) PVs. You parallel as many inverters as you have PV modules.”

Solar modules with preassembled micro-inverters will be easy to install once they are available. The AC panels in production are touted as “plug-and-play” products, so installation costs should be considerably less. The installation process seems easy enough, but we are not aware of plans for making them available to DIYers. The modules connect together to form an AC branch circuit, which is wired to a breaker in your house’s main panel. The micro-inverters eliminate the need to calculate inverter string sizing, but installers will need to stay within circuit breaker and service entrance limitations.

The advantages for having individual micro-inverters, whether integrated with the solar modules or not, are several.

As with any technology, there are many potential downsides. Here are several questions to consider.

You will need to carefully weigh the potential gains versus pitfalls in the technology. Smaller or incrementally installed solar-electric systems may be cost-effective. Other situations, such as systems with some shading problems or multiple orientations of panels, may benefit. People who have perfect solar sites and who are installing larger systems will need to make a very careful analysis, comparing projected reduced labor costs versus the cost of the equipment to assess the best value, while still considering all of the risks.

— Linda Pinkham, former managing editor of Home Power magazine