Two ways to build a 10 kW rooftop array are common. One puts a power optimizer behind every panel and feeds a SolarEdge inverter. The other wires the panels straight into a Fronius Primo GEN24 and lets two MPP trackers sort it out. Same roof, same panels, very different boxes.
This is a document comparison, not a test. I read the current North American datasheets, the manufacturers' warranty terms, the Fronius operating instructions and an independent shading study, and I haven't installed either system. Where a document is silent, I say so. The European three-phase models carry different numbers, so everything below refers to the US-market single-phase units: the SolarEdge SE10000H-US Home Hub inverter with P-series optimizers, and the Fronius Primo GEN24 10.0 (208-240 V).
What Are You Actually Comparing at 10 kW?
Not two inverters. One inverter against an inverter plus 25 small DC converters. That framing matters, because most of the differences below come from the converters, not the box on the wall.
| Specification | SolarEdge SE10000H-US + P401 | Fronius Primo GEN24 10.0 |
|---|---|---|
| Rated AC power | 10,000 W | 10,000 W at 240 V |
| Max DC input | 22,000 W at 240 V | 10,250 W usable, 15,000 Wp generator |
| Panel-level electronics | Optimizer on every module, 98.8% weighted | None by default |
| Max efficiency | 99.2% inverter, 99.5% optimizer | 97.5% at 240 V |
| CEC weighted efficiency | 99% inverter | 97% at 240 V |
| MPP trackers | One per optimizer | 2 |
| Cooling | Natural convection | Active, with fans |
| Enclosure | NEMA 4 (inverter), IP68 (optimizer) | Type 4X |
| Weight | 41.7 lb | 45.97 lb |
| Standard warranty | 12 years inverter, 25 years optimizer | 10 years, extendable to 15 |
Sources are the SolarEdge Home Hub datasheet, the P401 optimizer datasheet and the Fronius GEN24 datasheet. One caveat on the first two: solaredge.com blocks automated downloads, so these are distributor-hosted copies of SolarEdge's own PDFs. Check the date on whichever copy your installer quotes from.
Do the Efficiency Figures Settle It?
Not even close. A 99 percent CEC figure and a 97 percent CEC figure look like a two-point gap, and that reading is wrong.
The 99 percent belongs to the SolarEdge inverter alone. Every watt it handles has already passed through an optimizer, and the P401 datasheet gives that stage a weighted efficiency of 98.8 percent. Multiply them and the pair lands at about 97.8 percent (0.99 x 0.988 = 0.978). The Fronius datasheet's 97 percent is the whole chain from the DC terminals to AC.
Here's a worked illustration, and it is only that. Assume a 10 kW array producing 1,200 kWh per kW per year, so 12,000 kWh, and a power price of $0.15 per kWh. Both are my assumptions, not measurements from any site.
- On datasheet numbers, 97.8 against 97.0 is 0.8 points. That's 96 kWh, or about $14 a year in SolarEdge's favor.
- The IEA PVPS Task 13 group collected independent laboratory measurements of optimizers and concluded their real losses run around 2 percent higher than the 99 percent datasheet claims. Take that as a straight 2 point penalty on the optimizer stage, and the pair falls to about 95.8 percent. Now Fronius leads by 1.2 points, or 144 kWh and roughly $22 a year.
So the sign of the gap flips depending on whose numbers you trust. Both versions are worth tens of dollars a year on an unshaded roof. Efficiency is not the reason to choose either one. If the sums behind a CEC figure are new to you, reading solar inverter data walks through what each row means, and the Fronius vs Solinteg comparison shows how a headline figure can mislead even between two string inverters.
When Does Shading Change the Answer?
This is where the decision actually lives. The same IEA PVPS Task 13 report grades three shading levels and three hardware options, and its table is blunt about it.
With weak shading, meaning fewer than 10 percent of modules touched at once (a chimney, a vent pipe), a plain string inverter performs as well as optimizers on selected modules and better than an optimizer behind every panel. Between 10 and 40 percent of modules affected, standard modules on a plain string inverter fall to break-even, and optimizers pull ahead. Past 40 percent, from nearby buildings or large trees, the report says an optimizer on every module stays the most efficient variant.
The report also says that for light to medium shading the yield differences are usually under 4 percent a year, and that the key-takeaways box puts it under 3 percent for the market as a whole. Its authors add that a string inverter with shade-tolerant modules can often deliver comparable annual yield.
Where does that leave a 10 kW roof? If your shading is one chimney and a vent stack, Fronius's string-level Dynamic Peak Manager is a perfectly sound answer, and you'd be paying for 25 converters you don't need. If a neighbor's three-story building shades a third of the array every winter afternoon, the optimizers earn their keep. Count the modules in shade before you count the dollars.
With a chimney's worth of shade, an optimizer behind every panel does not beat a plain string inverter, and past 40 percent of modules shaded it does.
Which One Copes Better With a Complicated Roof?
Fronius has two trackers. That's the ceiling. The 10.0 allows up to 22 A usable on each, and Fronius's brochure says its SuperFlex design supports strings from three modules and different orientations on the two trackers. A simple east-west split fits that perfectly: five panels' worth of array each way, one tracker per face. Three orientations is where it runs out of tracker inputs.
SolarEdge sidesteps the question. The optimizer datasheet permits parallel strings of different lengths and orientations, with 8 to 25 P401 optimizers per single-phase string. At 400 W per module, 10 kW is 25 modules, so two strings (13 and 12, say) of roughly 5,200 W and 4,800 W, under the datasheet's 5,700 W string cap. The P401 is rated 430 W input, which covers a 400 W panel with room for tolerance. If you want to test a string layout on your own panels before a quote arrives, the string configurator checks cold-weather voltage against an inverter's window.
Does a single orientation need any of this? No. On one unshaded south-facing plane, both designs collapse to the same thing, and the cheaper bill of materials wins.
What Does Rapid Shutdown Add to the Bill?
Here the two documents say very different things, and the Fronius one is easy to misread.
SolarEdge's story is short. The optimizers hold each module to a 1 V safety output when the inverter is off, and the datasheets list rapid shutdown compliance for NEC 2014, 2017 and 2020 Section 690.12. It's built into the architecture, not added to it.
Fronius takes a different route. The GEN24 operating instructions describe a power line communication transmitter on the DC side, implemented to the SunSpec rapid shutdown specification and tied to NEC 2023 Article 690.12. Pressing a wired-shutdown button, or losing the grid, interrupts that signal and tells shutdown devices at the modules to act, but only devices that follow the SunSpec standard. The manual then warns that the inverter's equipment alone is not a complete rapid shutdown system, and that the installer must add other equipment to form one.
Read that twice. A Fronius-only quote with no module-level devices isn't a finished rapid shutdown design wherever your inspector enforces module-level control. Add them and the "no panel electronics" saving shrinks. Tigo's page listing Fronius inverters it has tested names the Symo, Primo and older families, and I couldn't find the GEN24 on it. Ask your installer for the exact certified pairing, in writing, before signing.
Monitoring, Service and Who Climbs the Roof
SolarEdge monitors every module, because the optimizers report individually; the optimizer datasheet lists module-level monitoring as a feature. There's a hook, though. The April 2026 warranty text makes coverage conditional on the products staying continuously connected to the SolarEdge monitoring platform, with temporary disconnections excepted. If an inverter stays offline and security updates go uninstalled, the text says SolarEdge cannot honor the warranty. Who in your household checks that the Wi-Fi link is still up?
Fronius lists Solar.web, Modbus TCP and a JSON Solar API on the datasheet, all inverter-level. It says nothing about per-panel data. If you want a panel-by-panel view, that means extra hardware and a compatibility check.
Service is the other half. A dead Fronius is one 46 lb box, indoors or out, on the wall. A dead optimizer is a roof visit, and the IEA report specifically flags the labor cost of replacing roof-mounted electronics and the possibility that higher operating temperatures make replacements more frequent. It says independent failure-rate studies are still missing. So nobody can honestly give you a failure rate for either path.
How Do the Warranties Compare?
SolarEdge's April 15, 2026 limited warranty gives power optimizers 25 years and other inverters, the Home Hub included, 12 years. Both clocks start at the earlier of four months after shipment or installation. The datasheet headline says "12-25 year warranty", but the extension terms weren't in any document I opened, so ask for the price and conditions in writing.
Fronius gives 10 years as standard, and the Fronius USA warranty page attaches conditions. The inverter must be registered on Solar.web within 30 months of delivery. A paid extension to 15 years has to be bought within six months of the warranty starting. The page itself is inconsistent about whether the ten years run from manufacture or commissioning.
And labor? SolarEdge's warranty states that labor, travel and the cost of uninstalling and reinstalling are not covered and fall on the buyer. Fronius's page says its paid extension covers materials, servicing and transport, and says nothing either way about the standard term. Pick up that gap in the contract with your installer, not with the manufacturer.
Which One Would I Specify?
My view, and installers will disagree: on a roof with one or two clean faces and light shading, take the Fronius and spend the saved money on a decent monitoring add-on or a bigger array. It's one box, nothing on the roof to fail, and the paper efficiency advantage SolarEdge holds may not survive independent measurement.
Choose SolarEdge when more than a tenth of your modules sit in shade at some point in the day, when the roof has three or more orientations, or when you're certain you'll want its DC-coupled battery later. Its datasheet lists the SolarEdge Home Battery and LG RESU Prime as supported. For the optimizer-versus-microinverter side of that choice, the power optimizer vs microinverter guide covers the third architecture, and the SolarEdge vs Enphase comparison prices it. Fronius's own battery route runs through a software upgrade to the GEN24 Plus, detailed in the battery inverter comparison.
Summary
At 10 kW, SolarEdge and Fronius are separated less by the inverter than by what sits behind the panels. On datasheet numbers SolarEdge's inverter-plus-optimizer chain is about 0.8 points ahead of the Fronius, and once the IEA PVPS Task 13 correction of roughly 2 points on optimizer losses is applied, the Fronius leads. Either way the difference is tens of dollars a year in an illustrative 12,000 kWh system. Shading decides it: under 10 percent of modules affected favors the string inverter, over 40 percent favors optimizers. SolarEdge brings 25 year optimizer warranty, built-in module shutdown and panel-level data, with a 12 year inverter and a monitoring-connection condition. Fronius brings two trackers, active cooling and one box to service, with a 10 year warranty, registration deadlines and a module-level shutdown design the installer must complete.