Enphase IQ8 vs IQ7: Is it worth the upgrade?

Enphase, the maker of the most popular microinverters in the US solar market, announced that it will be releasing the latest version of the IQ series later in 2021.

Product releases from Enphase are often a big deal, because microinverters and power optimizers now dominate the residential solar market, accounting for about 80% of all installations. New features from Enphase are good news for consumers, and also have the potential to move other inverter manufacturers to adopt those features to stay competitive.

The latest product in their inverter lineup is the IQ8 series, a follow up to the popular IQ7. The IQ8 lineup has a higher maximum output than its predecessor, but the big upgrade is the ability to provide off-grid power to a home even without a battery system.

Interest in off-grid power is growing due to cheaper battery prices and more frequent blackouts in places like Texas and California, but the cost of batteries is still high enough to be a barrier. By lowering the cost of off-grid power, the IQ8 microinverters have the potential to have a big advantage over its competitors. Unfortunately, the ability of the IQ8 to work off-grid comes with a major caveat.

More about that later. First, let’s take a look at the basics of this latest product from Enphase.

What does a microinverter do?

Solar panels are the most visible part of a home solar installation, but it’s really the inverter that is the heart of the system. The inverter turns electricity from your solar panels into alternating current that your house can use.

A standard inverter is a large unit, usually mounted near your electric panel, that does this conversion for all the solar panels in a system. But a microinverer is different: it’s a compact unit that does the conversion usually just for one panel. This means that, in most microinverter setups, you’ll have one microinverter for every panel in the system. Instead of being mounted near the electric panel, the microinverters are attached to the racking system that holds the solar panels.

There are big advantages to microinverters, such as better performance in the shade, the ability to monitor the power output of individual panels, and easier system expansion if you want to add more panels in the future.

The tradeoff for this functionality is cost, but the price difference is often small enough that it’s worth it for many homeowners. As mentioned earlier, most home solar installations now use microinverters or power optimizers. You can read this article on inverters to learn more.

The new IQ8 series: basic specifications

The IQ8 series consists of six products that are designed to accomodate a range of residential and commercial-sized solar panels.

Each model in the IQ8 lineup has the same basic functionality, and differ only by their power capacity. According to Enphase, features that are common to all of the IQ8 microinverters include:

• PV Rapid Shut Down compliant
• Lightweight and compact with plug-n-play connectors
• Power Line Communication (PLC) between components
• Faster installation with simple two-wire cabling
• Produce power even when the grid is down
• More than one million cumulative hours of testing
• Class II double-insulated enclosure

Which IQ8 microinverter should I use for my project?

There are six IQ8 models, each with a different power capacity. This is needed because solar panels are available with different power outputs and sizes. For residential applications, solar panels are roughly 65x40 inches. Commercial and utility installations use larger solar panels that are approximately 78x40 inches.

Larger solar panels generate more electricity, so commercial projects will use the higher capacity models such as the IQ8M, IQ8A, and IQ8H.

Smaller residential solar panels tend to top out around 400 watts, so the IQ8 and IQ8+ will be the right choice for most home solar projects.

One important detail is that it’s often smart to choose an inverter that has slightly lower power capacity than the maximum output of your solar panel.

Let’s say that you have a solar panel that has a power output rating of 375 watts. That’s higher than maximum input capacity of the IQ8, which means that you should move up to the IQ8+ right?

Not necessarily. That 375 watt solar panel will probably only hit that output level under very ideal conditions, which are bright and cold days. You might only experience that a few days a year. Because of that, it often makes sense to save money by going with a cheaper inverter and “throwing away” electricity on those few occasions when your solar panels are performing at their maximum.

This is called inverter clipping, and it’s part of the design of most solar arrays. If it seems like your solar contractor is choosing an inverter that’s too “small” for your system, ask them about inverter clipping and read our article on inverter clipping to learn more.

Standard solar arrays don’t work in a blackout

Many new solar homeowners are surprised when they learn that their solar panels don’t work in a blackout, even if it’s a sunny day. When a blackout happens, a conventional inverter will automatically shut down. This is to prevent solar panels from sending electricity into downed power lines and causing a dangerous situation for utility workers.

Normally, if you want your solar panels to continue to work in a blackout, you need a battery. With a battery, your solar system can disconnect from the grid and use its solar electricity to power your house and recharge the battery. While this is a great feature, it’s expensive: a battery system large enough to keep an average house fully powered through a long blackout can add $10,000 or more (before incentives) to the cost of a system.

If you only have occasional blackouts and can live without energy-sucking appliances like a central air conditioner for short periods of time, the more cost-effective solution is to buy a small gas-powered generator. While less convenient than a big solar battery or a large whole-house generator, it’s much less expensive and can provide enough electricity for a few critical applications, such as keeping your fridge from thawing.

It’s light off-grid situations like this where the new off-grid feature of the IQ8 can be a good, lower-cost alternative to a battery system.

Battery-less off-grid power with the IQ8

The new headline feature of the new IQ8 microinverter is the ability to provide electricity to your home during a blackout, with or without an integrated battery. There are two configurations:

• Off-grid power without a battery. In this setup, the IQ8 can supply as much electricity to your home in a blackout as the solar panels are generating in real-time. This means that when the sun stops shining, your electricity supply will stop until the blackout ends or the sun comes up again.
• Off-grid power with a battery. Like other solar inverters, the IQ8 can be paired with batteries to keep your house powered for as long as you have stored power.

While other inverters can be integrated with a battery to provide off-grid power, the only other inverter on the market that can provide off-grid power without a battery is the SMA Sunny Boy. Like the IQ8, the Sunny Boy can supply off-grid power and be paired with a battery, but in its battery-less configuratrion it can supply a maximum of 2,000 watts, even if your solar panels are generating more. This is a limitation that the IQ8 does not have. You can read our review of the SMA Sunny Boy to learn more.

Situations where the off-grid feature can be useful

If you don’t have a battery, the IQ8 microinverter can detect when a blackout happens. The system will then disconnect your home from the grid, and provide some power to your home for as long as the sun is shining. In this configuration the power supply to your home will fluctuate with the sunshine - sometimes dramatically.

For example, in bright midday light, an average home solar array could generate enough electricity to power a central air conditioner. But if a cloud passes over, that power output could suddenly drop by a couple thousand watts, starving your appliances of power and causing them to shut down. Because of this limitation, don’t expect to use this feature to supply electricity for power hungry appliances such as a washing machine, stove, or air conditioner.

On the other hand, you could take advantage of this feature to provide many hours of daytime power to low power appliances. A refrigerator, for example, needs only a few hundred watts of power. Because the average home solar array is around 6.4 kW, the IQ8 could supply enough electricity to keep your freezer from defrosting even on a cloudy day. You’ll likely have enough power to also keep your lights, internet router, and a computer or TV running.

Another way you could use this feature is to keep a portable battery charged. These batteries can be large enough to keep a refrigerator running through the night, keeping things cold until the sun comes up and the solar array starts generating power again.

One big caveat about the IQ8

This sounds great right? Unfortunately, the off-grid feature of the IQ8 isn’t a freebie. In order for your home to actually be able to switch to off-grid mode you need the Enphase IQ System Controller, which is a separate hardware component that retails for $1,700.

It’s the IQ System Controller that allows a solar home with the IQ8 to automatically detect when a blackout happens, disconnect your home from the grid, and keep your home powered as an “island” until the Switch detects that utility power has been restored. While $1,700 is a lot less expensive than a battery, it doesn’t include installation labor. In addition, you will likely need what’s known as a critical load panel installed in your home, which splits off a few important electrical circuits in your home that you want to keep powered in a blackout.

While both the IQ System Controller and critical load panel are usually a part of a solar battery installation, their requirement means that the IQ8 off-grid features don’t exactly come for free, even if they’re “included” in the microinverter.

Is the IQ8 a useful upgrade over the IQ7?

While Enphase emphasizes battery-less off-grid power as the hot new feature of the IQ8, its basic function as a microinverter remains the same. With an expanded lineup that includes more powerful models than the IQ7, the IQ8 will allow solar installers to choose an inverter that better matches the power output of the newest high efficiency solar panels, especially in large commercial sizes.

What if you don’t need off-grid power or you’re not using a high power commercial solar panel? If you’re a homeowner who is trying to save a few bucks, you might do just as well by choosing the older generation IQ7, which may be available at a discount now that the IQ 8 is on the market. For example, the Enphase online store currently sells the IQ 7 for $145 while the IQ 8 (which has the same power capacity) sells for $166.

That difference of $21 might not seem like a big deal, but with a typical home system that might have about 20 panels or more, you’d be saving at least a few hundred dollars by going with the older generation.