Every solar panel produces DC power, and your house runs on AC. Something has to do that conversion, and where it happens — at each panel or at one central box — is the single biggest architectural decision in a residential solar system. It affects your cost, your monitoring, how shade hurts you, what breaks first, and how painful an expansion will be ten years from now.
The two panel-level approaches dominating the market are microinverters (Enphase’s IQ8 family is the flagship) and power optimizers (SolarEdge’s core technology). Here’s how they actually differ, without the brand cheerleading.
How Each One Works
Microinverters are small inverters mounted under each panel. Every panel converts its own DC to grid-ready AC on the roof, and the AC from all panels joins on a shared branch circuit down to your panel. There is no central inverter — the roof is the inverter, distributed across every module.
Power optimizers are DC-to-DC converters mounted under each panel. They don’t make AC. Instead, each optimizer performs maximum power point tracking (MPPT) for its own panel — continuously finding the voltage/current combination that extracts the most power — then conditions the DC so the whole string feeds a single central string inverter, which does the DC-to-AC conversion for the entire array.
The shorthand: microinverters are panel-level conversion; optimizers are panel-level optimization with central conversion.
Both approaches solve the classic weakness of a plain string system, where panels are wired in series and the weakest panel drags down the whole string. With either technology, a shaded or dirty panel hurts only itself.
The Honest Comparison Table
| Microinverters (e.g., Enphase IQ8) | Power optimizers (e.g., SolarEdge) | |
|---|---|---|
| DC→AC conversion | At each panel | At one central string inverter |
| Central inverter required | No | Yes |
| Panel-level MPPT | Yes | Yes |
| Panel-level monitoring | Yes | Yes |
| Typical electronics warranty | ~25 years (microinverter) | ~25 years (optimizer), but ~12 years standard on the string inverter |
| Single point of failure | No — one failed unit costs one panel | Yes — inverter failure takes the whole array down |
| Where failures get fixed | On the roof (labor to access panel) | Usually at the inverter, at ground level |
| High-voltage DC on the roof | No (AC leaves the panel) | Yes (managed; drops to safe levels on shutdown) |
| Hardware cost per watt | Generally higher | Generally lower up front |
| Expansion later | Add panels + micros anywhere, largely independent | Constrained by string inverter capacity and string design rules |
| Battery pairing | AC-coupled ecosystem (Enphase batteries); IQ8 can form a microgrid | DC-coupled options; efficient storage integration in-brand |
| Very large/complex roofs | Scales panel by panel | String design needs more care across many planes |
Read that table with one caveat: both are mature, well-engineered technologies with enormous installed bases. Neither is a mistake. The question is which trade-offs fit your roof and your plans.
Where Microinverters Win
No single point of failure. If one microinverter dies, you lose one panel’s production and the other panels don’t care. With a string inverter, an inverter fault means the entire system produces nothing until it’s serviced. Given that central inverters are historically the most failure-prone component in any solar system, this is the strongest argument for micros.
Warranty symmetry. The panel-level electronics and the “inverter” are the same device, typically warrantied around 25 years — matching the panels. An optimizer system’s optimizers carry a similar warranty, but the central string inverter usually comes with about 12 years standard (extendable for a fee). Statistically, an optimizer-system owner should budget for one inverter replacement during the panels’ lifetime; a microinverter owner generally shouldn’t.
Expansion flexibility. Adding four panels to a microinverter system is close to trivial: four panels, four micros, connect to the branch circuit (assuming electrical capacity). Expanding a string-inverter system means checking whether the inverter has headroom and whether the new panels can be strung within the design rules — sometimes easy, sometimes a new inverter.
Complicated roofs. Panels facing three directions at three tilts? Micros genuinely don’t care; every panel is its own island.
Where Power Optimizers Win
Up-front cost. Optimizer systems are typically cheaper per watt on hardware, especially as systems get larger, because dozens of cheap DC devices plus one inverter costs less than dozens of full inverters.
Ground-level service for the expensive part. When the central inverter needs attention, a technician works at a wall-mounted box in your garage — no roof access, no pulling panels. Microinverter failures, though rarer per-system-outage, mean roof work.
Conversion efficiency on paper. A single large inverter runs at very high efficiency, and SolarEdge’s optimizer architecture posts excellent CEC efficiency numbers. In practice the real-world production difference between the two architectures on an unshaded roof is small — low single digits at most — and shouldn’t drive the decision by itself.
DC-coupled storage. Charging a battery from DC solar without an extra AC conversion round-trip is slightly more efficient, and SolarEdge’s ecosystem is built around that.
What About Plain String Inverters — and Tesla?
Worth saying clearly: panel-level electronics are not mandatory. A plain string inverter with no per-panel devices is still sold, still cheaper, and still fine on a simple, unshaded roof. Our own 40-panel system runs on two Tesla string inverters — neither microinverters nor optimizers — because the roof planes are largely unshaded and the per-panel electronics wouldn’t have earned their cost. What we gave up is panel-level monitoring: we see production per inverter, not per panel, so identifying one underperforming module means more detective work.
Tesla’s ecosystem generally follows this string-based philosophy — the Powerwall 3, notably, has a solar inverter with multiple MPPT inputs built into the battery itself, which collapses the “inverter vs. battery” decision into one box for new installs. US electrical code’s rapid-shutdown requirements mean even string systems now include module-level shutdown devices on the roof, which narrows the safety gap that once separated these architectures.
How to Actually Choose
Skip the brand-war forums and answer four questions:
- Is your roof shaded or multi-directional? Heavy shade or 3+ orientations → panel-level electronics earn their cost, and micros handle the messiest roofs most gracefully. Clean unshaded south roof → even a plain string inverter is defensible.
- Will you expand later? Planned EV, heat pump, or an addition → microinverters make future growth cheapest and simplest.
- Are you adding a battery now? Get the battery and inverter architecture designed together. Enphase pairs naturally with its AC-coupled batteries; SolarEdge with DC-coupled storage; Powerwall 3 wants to be the inverter.
- Who’s servicing it in year 15? Both major ecosystems are established, but ask your installer what they stock and service locally. The best architecture is worth less than the one your local installer can fix in a week.
Then get quotes for both architectures on your actual roof. The price gap is often smaller than the internet suggests, and seeing real numbers for your specific site beats every generic comparison — including this one.