What is an AC solar panel?

Solar panels generate DC electricity, but more companies are selling AC solar modules. In this article, we’ll explain what these are.

Example of an AC module (Courtesy Panasonic)
Example of an AC solar panel (Panasonic HIT)

Solar panels are magical things that turn sunlight into electricity. The electrons that flow out of a solar panel move in a steady stream, known as direct current (DC).

However, grid electricity is alternating current (AC), so the power from solar panels must be converted from DC to AC before it can be useful to your home. That’s the job of an inverter, which you can read about in detail in our guide to solar inverters.

These days, you’ll find some manufacturers selling AC solar panels, and more and more are jumping on the bandwagon. But what does that mean?

An AC solar panel is one that has a microinverter built-in. The microinverter converts the DC power generated by the solar cells into AC power. This saves time and labor costs, because the installer doesn’t need to handle the inverter installation.

If you’re thinking of going with a microinverter-based system anyway, AC panels might be a smart choice.

Crash course on solar inverters

There are different types of solar inverters, and choosing the best one for your home is one of the key decisions you’ll need to make when designing a system with your solar contractor.

There are three main types to consider:

  • String inverters are centralized inverters that handle the output for a group of solar panels. Large systems may need more than one inverter. The main advantage of a string inverter is lower cost, but the tradeoffs are that a string inverter-based system can have trouble with shaded roofs, and you’re unable to monitor the output of individual solar panels.
  • Power optimizers are based around a central string inverter, but with this type of system each solar panel is paired with a small electronics module called a power optimizer. The optimizer allows the system to better handle shading, and lets the system monitor each panel individually.
  • Microinverters do away with the central inverter entirely. Instead, each solar panel is paired with a miniatured inverter that handles the output for that panel. This makes for the most flexible system available, but at a higher cost.

With either a power optimizer or microinverter system, an electronics package is mounted behind each panel by the installer. While this adds some cost, for many situations the payback in higher efficiency is worth it.

Here’s a summary:

string inverter• Least cost• Least effective in shade
• Single point of failure
• May limit future system expansion
power optimizers• Handles shading well
• Panel-level monitoring
• Expansion limited by string inverter
• String inverter is single point of failure
• Not as shade-tolerant as microinverters
microinverters• Handles shading well
• Panel-level monitoring
• Single failures do not impact system
• Easiest to expand in the future
• Highest cost

What is an AC solar module?

An AC solar module - also known as a solar panel (the terms are used interchangeably) - is simply a solar panel with a microinverter mounted at the factory. This means that if you go with AC solar modules, there’s no need to choose an inverter system, as the inverter choice is already made.

In many cases, the solar panel manufacturer isn’t making their own microinverter, but instead partnering with an inverter company. A common manufacturing partner is Enphase, which is the leading company in the microinverter segment.

List of AC solar modules on the market

Enphase is the largest microinverter company, and they’re currently partnering with four solar panel companies to jointly produce AC modules. These include:

  • SunPower (A-Series)
  • QCells. Various generations of the popular Q.PEAK DUO series include an AC option
  • Solaria. (PowerXT AC Series)
  • Panasonic. (N330E HIT AC Series)

Reasons to choose an AC solar panel

A big advantage of an AC panel is labor savings at installation time. Because the panel leaves the factory with the microinverter pre-installed and wired, there is less work for your solar installer to do. Normally installing a microinverter means a component to bolt to the racking system and cables to manage.

AC panels eliminate that step, which means faster installation time. In theory, that should result in lower labor costs for your project.

Finally, the warranty that comes with an AC solar module is often better than what you’ll find with a conventional solar panel. While Enphase microinverters normally come with 25 year product warranties, most solar panels have separate power and product warranties, the latter of which can be as short as 10 years.

However, every AC solar module that is currently on the market (that we know about) comes with a 25 year product and power warranty. This means that if either the microinverter or the panel fails after 24 years, that failure will be covered by the warranty.

AC modules: maybe a good way to save money?

Solar panel manufacturers struggle to find ways to differentiate their products, so it’s great to see them bring new products like AC modules to the market.

For the homeowner, the main potential benefit is cost savings compared to purchasing solar panels and microinverters independently, and lower installation costs.

Whether these theoretical cost savings actually materialize for you will depend on your solar installer.

#Panel Technology #Microinverters

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