Solar inverters: types, benefits and cost

What is a solar inverter?

A solar inverter is a piece of electrical equipment that converts (or “inverts”) newly generated direct current (DC) electricity into alternating current (AC) electricity. Inverters are almost always necessary to use electricity generated by solar panels, whether you’re assembling a small DIY system or a large community solar array. You can generally find inverters installed beneath solar panels, inside a garage or on the side of a house.

What does a solar inverter do?

Without diving too much into the technical details of how electricity works, a good rule of thumb to remember is that solar panels generate DC power, while homes, buildings and the electrical grid run on AC power.

Therefore, a solar inverter's job is to modify the DC electricity created by a set of solar panels into AC for on-site use or transmission to another end user somewhere along the grid.

Solar-derived electricity may also travel through several other pieces of equipment before it reaches the inverter. For example, in an off-grid solar energy system, new solar power must first be sent through a charge controller to condition the electricity before it can be safely stored in the battery or modified by the inverter.

If you're designing your own solar energy installation, you need to make sure your solar inverter is properly wired to the rest of your system’s components in order to safely generate and use the new clean energy.

» MORE: How do solar panels work?

Types of solar inverters

Solar inverters come in many different sizes and power capacities. Today, many new photovoltaic (PV) installations utilize either a string inverter or a microinverter. However, you can also get an inverter prepackaged together with a charge controller, battery and other components by buying a solar generator.

String inverters

Commonly found in solar energy systems for homes and businesses, string inverters (also known as central inverters) connect several panels along separate “strings.” By wiring together multiple panels and sending the electricity to one central point, a string inverter can efficiently convert solar power without the need to install additional pieces of equipment.

The primary drawback of using string inverters is that the total solar potential for each string of panels may be limited by the weakest-performing panel. While most solar panels will generate a similar amount of electricity when installed side by side in full sun, if just one portion of a single solar panel in a string becomes shaded, it can significantly lower the string’s total production.

Solar panels are usually under warranty for at least 20 years.

Additional pieces of hardware known as power optimizers can help avoid this, though. John Striebel, CEO of the Denver-based solar company Apollo Energy, told us, “When you add power optimizers to solar panels connected to a central inverter, you can avoid lower overall production levels if one panel in the chain is underperforming.” However, power optimizers add cost and complexity to your PV system, diminishing some of the main benefits of string inverters.

String inverters are usually much cheaper than microinverters to install and maintain. However, most string inverters are only rated for 10 to 15 years of performance, which means you’ll likely need to replace your string inverter at some point in the lifetime of your solar panels.

String inverter pros and cons

There are upsides and downsides to string inverters; they're affordable, but they're not as efficient as other inverters.

» LEARN: How long do solar panels last?

Microinverters

Much smaller in size than a traditional string inverter, a microinverter is a module-level power electronic (MLPE) that is typically attached to the underside of a solar panel. This technology lets you have a system powered by multiple microinverters instead of a single string inverter.

By converting new clean energy into alternating current as soon as it's generated by each solar panel, microinverters can help you avoid some of the power capacity losses associated with string inverters.

Microinverters’ panel-by-panel setup also helps keep a PV system running closer to its maximum capacity if part of the solar array becomes shaded or damaged. And microinverters make it much easier to add more solar panels later on. These benefits are enough to sway many people away from string inverters, including Megan, a ConsumerAffairs reviewer from Marysville, Ohio.

Microinverter pros and cons

While microinverters are generally seen as a more efficient technology than string inverters, they are also more expensive to install and can be a headache to replace if they fail.

Solar generators

If you're assembling your own small solar energy system, you may find it easier to purchase your inverter as part of a solar generator or portable power station. Solar generators typically include an inverter, battery and charge controller in one handy package.

In addition to saving space, one of the biggest advantages of utilizing a solar generator for a DIY system is that each component has already been thoughtfully paired together to work safely and efficiently.

By simply plugging in a set of panels to a solar generator, you can safely generate new electricity without having to worry about overloading your charge controller, inverter or battery. You just have to make sure your panels’ total output is below the generator’s maximum input capacity.

Solar generator pros and cons

Solar generators are straightforward in terms of installation, but they're not ideal for large-scale systems.

» MORE: What is a solar generator?

How much do solar inverters cost?

Like nearly every other aspect of solar energy installations, the upfront and long-term costs of your inverter(s) will depend on the size of your system as well as the quality of the equipment you buy.

Lower-capacity inverters for small DIY solar energy systems (like a handful of panels on an RV or cabin) typically retail below $500. However, you can expect to pay somewhere between $1,500 and $3,000 or so to purchase and install a string inverter or set of microinverters for a residential system.

While you want to account for the cost and efficiency of your inverter as you calculate whether solar panels are worth it, it’s important to remember that inverters usually only make up a fraction of your overall solar power system expenses.

» MORE: How much do solar panels cost?

Bottom line

Solar inverters ensure that the energy produced by your solar panel system is usable in your home. By converting DC power into AC power, solar inverters make it possible to run home electronics on solar power or send energy out to the power grid.

If you’re assembling your own small PV system, purchasing a solar generator is a great way to get an inverter, charge controller and battery that work together to efficiently process and output usable solar power.

If you’re working with a solar energy company to set up a system for your home or business, the company will likely bring its own inverter recommendations to the table. However, understanding the differences between string inverters and microinverters can help you make a more informed decision that suits your system’s power potential and budget.