Which Solar Inverter is Best for Your Home?
Inverters are a solar system necessity but which kind to get is not so complex and we have the answers you need. Any home solar power setup must change solar panel power (which is DC) into the kind of power your household plugs use (which is AC); that’s what the inverters do.
SolarEdge and Enphase are industry leaders serving most of the US market so they’re a good source of guidance. Their products are clearly different, too, so they serve as easy education material as well.
Typical inverters are often large box-like devices you might see on the side of a house but that’s not the only option anymore, as “microinverters” can also be used. A microinverter is a small circuit installed on each solar panel—so there’s no big box—and you’ll never know they’re there except for one item: Cost. While microinverters are easier to install, almost never fail and are well hidden, they do cost more than the single big box kind. Are they worth the extra expense? We’ll lay out what you need to know.
If you already have solar power and your inverter fails, you’re stuck with the box on the wall “string inverter” unless you want a big upgrade bill.
Enphase makes microinverters that can be installed with almost any solar panels, but you can also get panels with these inverters built in, including ‘designer’ panels that are completely black. (Enphase is by far the most popular microinverter brand in the US.) Built in or added on, microinverters do have some strong selling points. Enphase microinverters are solid performers that last a long time. Enphase-equipped systems will often give you a superior warranty for that reason, often 25 years. (Old Enphase systems had some issues but those are long gone.)
You also never have to look at those big box devices, but there is something to know; in the unlikely event that one of these small inverters fails it must be replaced by going up to the panel, on the roof. There is a silver lining, though, since one inverter failure just means one panel stops working.
The current line of Enphase products is the IQ 7 series but with lower power output panels you might get a bit of savings using the previous model, the IQ 6. Newer panels generate stronger power output, though, so expect to see “IQ 7” on a parts list.
The box-on-the-wall approach feeds all the wires from the panels to one central inverter, in this case the SolarEdge HD-Wave inverter. The benefits are lower cost and ease of maintenance, but again there is a price to pay. The larger central inverters don’t last as long as the small ones so your warranty will be 12 years instead of 25.
In addition, a failure of this one big inverter means the entire system is off-line until that is replaced. A house-sized inverter can be a bit costly, too, whereas the one-at-a-time microinverters are inexpensive. (The odds of all the mini-inverters failing at the same time are quite small.)
SolarEdge systems also pair the inverter with a power optimizer (yes, another box) that strongly upgrades how power is used. Without this extra step, any variation in the power coming from your panels—like part of the roof being in the shade—can affect the whole system. Power optimizers are generally thought of as essential although some budget systems might omit them.
The SolarEdge setup uses a “maximum power point tracker” add-on to make the best use of the power coming from your panels. An MPPT treats each panel as a separate power source so if one panel isn’t getting full sun the whole system doesn’t suffer. Power optimizers usually last longer than central inverters and the SolarEdge MPPTs have 25-year warranties.
Is there a big choice between one kind and the other? Not really, not anymore. If one of the tiny inverters fails, the system will still get full power from the rest of the system—a real benefit—and For this great feature (the whole system doesn’t just stop) total efficiency drops to about 97%. SolarEdge string inverter + optimizer systems are usually more than 98% efficient. Overall, this difference is too close to call.
Warranties don’t normally cover labor costs so the worry (such as it might be) is equipment failure. As noted, the trade-off is shorter 10 to 12-year life for the less costly central system or having to get on the roof to tinker with a small inverter, probably several years later. Even after a 25 year warranty ends, the availability of the system when a microinverter fails makes them an attractive choice since only one panel goes off-line. If long term reliability is worth a bump in price, then your best bet will be a microinverter setup.
No system is ever perfect and both companies have suffered some issues through the years. Enphase had issues with previous microinverter models, but those issues seem to be solidly gone, with warranties extended from the previous 15 years to an industry-leading 25 years. SolarEdge had issues with some inverters and power optimizers in recent years, including in 2018 and ’19, but their gear seems to be on the mend recently. They’re a publicly traded company, too, which means they are highly motivated to stay on top of any issues.
Knowing what’s going on with your system can be critical, and both Enphase and SolarEdge allow you to check in with your smart phone or at the control panel. Once more, though, there is a difference in cost. SolarEdge inverters have monitoring capabilities built into the system whereas Enphase units require a separate, centralized monitoring device – which costs extra. Enphase uses a unit called the IQ Envoy that sends data online where you can retrieve it as you like.
Both systems tell you what’s going on, how much power you are generating, and both can give you reports to download.
The Tesla Powerwall is still the market leader, is the more powerful of the three and is usually the least expensive option. The Tesla solution seems an easy decision but Enphase and SolarEdge offer discounts sometimes that might tip the balance on your budget.
Enphase and SolarEdge both offer a 10 kWh (kilowatt hours) unit while the Tesla Powerwall comes in with 14 kWh.
Hopefully, we’ve painted a clear picture of two quite different kinds of systems, so bottom line, yes, you can trade off some savings for some advantages. With improved MPPT systems (wall-sized inverter plus power optimizer), for instance, there is not much difference in the quality of power between the two. You can likely save some cash with the wall-mounted units.
If you can afford the higher price of microinverters, though, the benefits seem worthwhile. The warranties last longer for the simple reason that microinverters last twice as long as the larger central one, and if one little microinverter fails it leaves the rest of the system working. Your power might drop a little, but it won’t stop altogether.
The deciding factor may well hinge on this question: How long are you willing to be without power if a single big component fails? What if it takes a long time to get an inverter replaced?