Enphase IQ7 Versus IQ8 Microinverters

UPDATE 2/16/24: Enphase is discontinuing the IQ7 series of microinverters, so much of this article is a moot point, but there is still a ton of valuable information here. We are keeping it here for you for historical reference.

 

The IQ8 series of microinverter has been out for a while now, and it has proven to be another great product from the leading microinverter manufacturer, Enphase. But is the IQ8 better than the IQ7 series? You might be very surprised when comparing the IQ7 versus the IQ8.

When considering the variants of each, the power output ratings are the same. For example, the IQ7A and IQ8A have the same peak and continuous output capabilities. The same thing applies to the IQ7PLUS and IQ8PLUS (also known as the IQ7+ and IQ8+). They have all of the same basic input and output specifications when used in a grid-interactive solar energy system.

The IQ8 was designed from the ground up to handle household backup, but they can’t do that job without other components. And with other components, the IQ7 can also do household backup with the utility grid goes down. So why would Enphase bother with developing the IQ8 when the IQ7 can also do backup? Well, technically, the IQ7 can’t do backup without some IQ8s because the IQ8 is embedded in their batteries. But the IQ8 has a little trick up its sleeve – sunlight-only backup without batteries.

Is the IQ7 Better?

Let’s start by explaining two reasons the IQ7 might be a better choice for you.

  1. If you intend to simply reduce your utility bill with a grid-interactive solar energy system, and don’t intend to do backup, the IQ7 does the same thing for a lower cost. You could save hundreds, or even thousands of dollars and get the same outcome.
  2. If you do intend to have a battery backup system, there is a hard limit to how many IQ8 microinverters you can have, and that limit is lower than the number of IQ7 microinverters you can have to recharge your batteries. The reason is a little technical, but the short explanation is the required System Controller can only handle 64 amps of input from IQ8 microinverters because of the way that rapid shutdown requirements are implemented. If you have a very large solar array and a large battery, the IQ7 could very well be the superior choice.

So if you want a budget-friendly option, in many scenarios, there is no reason to go with the IQ8 over the IQ7, and in some cases, the IQ8 can actually limit your capability.

Enphase IQ8 Microinverter
The IQ8 Microinverter is the latest from Enphase.

Why Does the IQ8 Exist?

If the IQ7 is so great, why did Enphase develop the IQ8? As mentioned above, the IQ8 is embedded in Enphase’s “batteries” (which are actually Energy Storage Systems incorporating a battery and inverters). The IQ8 was developed as a “multi-mode” inverter, meaning it can charge a battery or discharge the battery to a home or the grid. It works both ways at converting AC to DC and DC to AC. That differs from the IQ7 which simply converts DC to AC that can be used when connected to the grid.

Because the IQ8 is multi-mode, it also has the capability of forming an “island,” or microgrid, without the utility grid present. This allows the IQ8 to provide power to the home during daylight hours. This is actually pretty revolutionary in our industry, since most solar panels just sit idle during a grid outage. But there are serious limitations to sunlight-only backup aside from it only working during daylight. The biggest challenge is the variability of solar irradiance as clouds pass over and as the sun’s position changes throughout the day. The solar panels will only be able to provide a limited amount of power. The sunlight-only backup system is not designed for whole-home backup. It is only intended to cover a very short list of emergency backup circuits.

That usually means no air conditioning unless you also have storage batteries. Nonetheless, the sunlight-only backup system has its place in the market, and you might be interested in it despite the limitations. The IQ8 is the only microinverter that can do this.

But At What Cost?

As you might imagine, all of this technology comes at a cost. The IQ8 price can be several hundred, or thousands of dollars more for some systems when compared to the equivalent output IQ7 model. But to get the benefits of backup, you need additional gear. In the case of battery backup, you need the batteries (of course) and a System Controller, which is a sophisticated and expensive Microgrid Interconnect Device (MID). For Sunlight-Only backup, you still need the MID, and you will need to carve out a critical load panel with circuit breakers for your backed-up loads.

This doesn’t come cheap. We’re talking about thousands of dollars for the MID itself, just to get any benefit from the IQ8. Right out of the gates, you have a large fixed cost to absorb regardless of how many solar panels you are installing. This is particularly bad if you are installing a small system. The numbers just don’t look good.

Why Are Competitors Offering The IQ8 Exclusively?

It’s a lot easier to be lazy and just offer the newest model and tell clients that it’s obviously the best. Since most dealers are doing this, they don’t have to worry about the price competition that the IQ7 allows. Some dealers might want to limit their inventory to save costs, which is a legitimate reason, but it isn’t to save you money.

The IQ7 is still a fantastic microinverter that does everything an IQ8 can do in the vast majority of circumstances we run into. In some cases, it’s the technically superior option or even the only good option.

My advice to you is to ask them why… and watch the poor salesperson squirm.

When Is the IQ8 The Right Choice?

Of course, we do offer the IQ8 microinverter and do recommend it in some cases. If you have any thoughts about installing a grid-interactive system now and upgrading to batteries later, it is not a terrible choice. While the IQ7 works great in a battery backup scenario, the IQ8 has faster switching, which offers some advantages in a grid-down scenario. On the other hand, if you are planning a larger system, you might run into limitations with the number of microinverters that can charge your batteries in an off-grid situation.

If you want sunlight-only backup, either now or potentially later, the IQ8 microinverter is the only way to do that. The IQ7 does nothing for you in a backup scenario unless you also have batteries.

There are a couple of IQ8 variants that do not have direct IQ7 counterparts. In particular, the commercial versions of the IQ8 and the IQ8M fills a hole for some mid-wattage panels on the market. But for the typical residence, the IQ8+ or IQ8A will work for most panels we offer in Southwest Florida.

A Note On The Marketing Double-Speak

Enphase IQ8 Backup Monitoring
An Enphase IQ8 Backup System In Action.

Of course the manufacturer is going to make the IQ8 sound fantastic, touting the speed and proprietary architecture. That’s nice, but if you look closely at the brochures, you will notice that almost all of the bullet points are the same for both the IQ7 and IQ8 series. One significant line in the IQ8 brochure is important, however:

“[The IQ8 has] superfast response times to changing loads and grid events, alleviating constraints on battery sizing for home energy systems.”

The first half of that sentence is kind of necessary. If it didn’t have that, it wouldn’t work to provide backup capability. The second sentence points out a benefit while leaving out a very important point. Enphase advertises “no limit” on the number of IQ8 microinverters charging a battery. The idea here is you can have a very small battery with a very big IQ8 solar array. Ok, that’s a fair benefit. But the reality is that there IS a limit, and that limit is 64 amps, which is 44 x IQ8A or 52 x IQ8+.

The IQ7 is “limited” to 150% of the battery output, so the battery size matters. But what happens if you have a larger battery, which is often required for backing up air conditioners here in Southwest Florida? The limit of IQ8 microinverters does not change. However, you could have as many as 66 x IQ7A or 78 x IQ7+ when using Encharge 10 batteries. In fact, you could even have double these quantities if using the new Enphase 5P batteries with a maxed out battery system. With the IQ8 you are limited to 64 amps no matter what.

Put another checkmark in the IQ7 column.

Should You Buy IQ7 or IQ8?

If you just have to have the latest tech, no problem. Get the IQ8. It’s going to cost you a little more and it will give you the peace of mind of having an upgradeable system, to a more or less extent as we explained above.

If your needs are basic and you are looking for the best return on investment, the IQ7 is probably going to be your best option in most cases.

If you are definitely doing a backup system, or are considering it for the future, we are recommending that you go with the IQ8, but if you buy the IQ7 don’t worry – there will be an upgrade path for you in the future. In fact, both the IQ7 and IQ8 are compatible with other manufacturers’ battery options currently on the market, and that will continue in the future. While we recommend that you stick with a unified system from one manufacturer, there is nothing wrong with mixing the Enphase microinverters with another company’s batteries and a separate multi-mode inverter. It might actually be a better or lower cost option in some scenarios.

Things are getting more complicated in the microinverter business. Previously it was always the obvious choice to buy the latest generation of microinverter technology from Enphase, the clear and far-and-away leader in microinverter technology and sales. But things are changing as batteries start to take center stage and backup systems have become more popular.

It’s a constantly changing market, and you can count on Florida Solar Design Group to stay on top of the latest tech and advise you properly based on your needs. Following the trends and taking the path of least resistance isn’t always the best answer. The IQ7 and IQ8 are both great products. We will help you make an informed decision.

 

 

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