Best Solar Inverter for Your Home: Enphase vs SolarEdge vs Tesla

It’s the inverter.

If you’re with PG&E, SCE or SDG&E and you’re getting solar quotes, you’ve probably seen Enphase, SolarEdge, Tesla and maybe Qcells. Every rep will tell you theirs is the best. Funny how that always matches whatever their company installs.

I’ve worked in California solar for 13 years. Here’s how the three main types really compare, the five questions to ask before you sign, and which one I’d put on my own house. Hint: it depends on your roof more than the brand.

What a solar inverter does

Your panels make DC power, the same kind a battery makes. Your home runs on AC power. The inverter converts one into the other.

Every kilowatt-hour your panels make has to go through it. So if the inverter stops, your panels can sit in full sun and make nothing your home can use.

That’s why it matters how long it lasts. Solar panels typically come with 25-year warranties, and they’re built to last that long. A traditional string inverter, the box that hangs on the side of the house, typically lasts about 10 to 15 years, according to EnergySage.

So on a 25-year system, a lot of homes will need at least one inverter replacement. What that costs outside of warranty depends on the quote. But it’s never a number anyone’s happy to see.

It’s the least exciting part of your system. Nobody’s ever posted a selfie with their inverter. But it’s the part I’d ask the most questions about.

The three main types of solar inverters

Almost every quote I see in California uses one of three setups:

Here’s an honest look at each one.

Microinverters (Enphase, Qcells)

The upside. Every panel works on its own. If one panel gets shade from a tree at 3 in the afternoon, only that panel slows down. The rest keep producing.

There’s also no single point of failure. If one microinverter dies, you lose one panel’s worth of power, not the whole system.

The warranties are long. Enphase gives its IQ8 microinverters a 25-year limited warranty in the U.S., and Qcells lists its own microinverter with a 25-year warranty.

One detail I like about Qcells: their AC panels come with the microinverter already built onto the panel, and one company warranties both. If something goes wrong, there’s one company to call, not two companies pointing at each other.

The downsides. All of those little inverters live on your roof. When one fails, someone has to get up there to replace it. Ask whether the warranty covers that labor or just the part.

They can also cost more up front than one central inverter, especially on a big system with a lot of panels.

And if you want a battery, an Enphase system usually pairs with Enphase batteries. You can add another brand, like a Powerwall, but then you’re mixing brands, and the power gets converted an extra time on its way in and out of the battery.

SolarEdge (optimizers + one inverter)

SolarEdge is kind of a middle ground. Every panel has an optimizer, so shade on one panel doesn’t drag down the others nearly as much as an old-school string system. You still get panel-by-panel monitoring in the app.

The power optimizers carry a 25-year warranty. SolarEdge’s standard home inverter has a 12-year warranty, and it can usually be extended.

That difference is the whole story. The optimizers on the roof are covered for 25 years. The box on the wall, the part every panel depends on, is covered for 12 unless someone paid to extend it.

So SolarEdge does have a single point of failure. If the central inverter goes down, the whole system stops until it’s repaired or replaced. To be fair, that inverter is on the ground, not on the roof, so it’s a lot easier to reach.

What about SolarEdge Nexis?

Nexis (with an "i") is new from SolarEdge this year. It’s one inverter that runs both your solar and your battery. The battery comes in blocks of about 5 kWh each that stack together, up to 4 per stack (about 20 kWh). So you can start smaller and add blocks later.

The line I’d check: on the U.S. datasheet, the Nexis inverter has a 10-year warranty, not 12. The battery is also 10 years. So the question of who covers it comes up two years sooner.

Where I think Nexis makes the most sense is a home with an older SolarEdge system that needs a new inverter anyway. In a lot of those cases (if your optimizers are SolarEdge’s P-Series or S-Series), it works with the optimizers already on the roof. So you can replace the inverter and add a battery in the same project.

If a quote shows SolarEdge, my first question is simple: "Which inverter is this, who covers it after the warranty ends, and is that in writing?"

Tesla Powerwall 3 (inverter built into the battery)

A lot of homeowners ask for this one by name when they want backup power, so I’ll be straight about it.

The solar inverter is built into the battery, so the panels feed it directly. That means fewer boxes on your wall, and your panels can charge the battery without an extra conversion step.

Tesla rates it at 97.5% efficient from the panels to your home. That’s right in line with the good microinverters, so efficiency isn’t really where this choice is won or lost.

The trade-offs:

• One unit, one warranty. The Powerwall 3 has a 10-year warranty, and it’s one central unit. Like SolarEdge, if it goes down, your solar and your battery are both down until it’s fixed.
• Shade. It has several separate solar inputs, so panels on different sides of the roof can each get their own. But panels that share an input still share. Heavy shade on one can pull down the others on that input.
• Size. One Powerwall 3 can only send so much power into your home at once (11.5 kW continuous). On a large system, the panels can make more than one unit can handle in the sunniest hours, and that extra power is lost. On bigger systems, I’ll often design two Powerwall 3s for exactly that reason.

So which solar inverter is best?

Here’s the honest answer, and it’s probably not what the last rep told you. The brand matters less than three things: your roof, your battery plans, and who’s on the hook when the inverter breaks.

1. Your roof. If you’ve got shade, or panels spread across three or four roof faces, I lean toward microinverters or SolarEdge, because each panel gets managed on its own. If you’ve got one big sunny roof with no shade, all three can work well.

2. Your battery plans. On NEM 3.0, a battery is often what makes the numbers work, because the credit for power you send back is only about 5 to 8 cents per kWh. So if you want a battery, the inverter choice is really a battery choice. With Powerwall 3 or Nexis, the inverter and battery come together. With Enphase, you’d usually pair an Enphase battery. With Qcells panels, it’s the Qcells battery, which is the one I reach for first these days, because it can come in lower than a Powerwall 3.

One thing a lot of people don’t know: without a battery, most solar systems shut off when the grid goes down, even in full sun. That’s a safety rule, so line crews don’t get hurt working on the lines.

If you’re with LADWP or another city-run electric company, you’re not on NEM 3.0, so the battery math is different for you.

3. Who fixes it, and for how long? This is the one most people skip.

• Under the zero-down lease I sell most, the company is responsible for monitoring, maintenance and warranty repair or replacement, including the inverter, for the whole agreement term.
• With a prepaid lease, it depends on the contract. With one I offer, maintenance is covered for the first five years and the installer’s workmanship for ten. After that, you’re leaning on the manufacturer’s warranty, which is one more reason to pick an inverter with a long one.

Already have solar and your inverter died?

If you’re on NEM 1.0 or 2.0, replacing a dead inverter keeps your plan, as long as the system doesn’t grow by more than 1 kilowatt or 10 percent, whichever is bigger.

Where people get in trouble is when a rep bundles extra panels into the repair. Go over that limit, and your whole home can move to NEM 3.0. (Here’s how the three plans compare.)

If you need more power too, there are two ways to add it. One keeps your old plan. The other has nothing upfront and moves you to NEM 3.0 with a battery. I run the numbers both ways, and you pick.

What I’d put on my own house

For most homes, especially with shade or a lot of roof angles, I’d go with Qcells panels with the microinverter built in, plus the Qcells battery. One bad part never takes the whole system down, and one company warranties the panel and the microinverter.

If I had a big, sunny roof and wanted to keep a big AC running in an outage, I’d go with the Powerwall 3, sized properly, and two of them if the system is big enough to need it.

Either way, I’d want the repair coverage in writing.

5 questions to ask your solar rep about the inverter

1. "Which inverter is this, and why did you pick it for my roof?" If the answer is "it’s what we always use," that’s not a design. That’s a habit.
2. "How long is the inverter warranty, not just the panel warranty?"
3. "Does the warranty cover labor, or just the part?"
4. "If I add a battery now or later, how does it connect to this inverter?"
5. "Who do I call when it breaks in year 14, and is that in writing?"

A good rep answers all five without blinking. A rep who says "I’ll let the installer deal with that" is telling you who’ll really be dealing with it later. And that’s you.