Microinverters vs string inverters
Choose microinverters if your roof is shaded, faces multiple directions, or is complex. Choose a string inverter if it is one clean unshaded plane and you want to save money. The difference matters most where shade is involved, because a string inverter lets one shaded panel drag down every panel wired with it.
The core difference
A string inverter converts DC to AC for a whole group of panels at once, so the group performs close to its weakest member. Microinverters sit under each panel and convert individually, so a shaded panel only costs you that panel.
| String inverter | Microinverters | |
|---|---|---|
| Cost | Lower — one unit | ~10–20% more system cost |
| Shade tolerance | Poor | Excellent |
| Multiple roof planes | Needs separate strings | Handles natively |
| Per-panel monitoring | No | Yes |
| Warranty | 10–15 yrs | 20–25 yrs |
| Replacement | One unit, at ground level | On the roof, under a panel |
| Failure impact | Whole system down | One panel down |
Power optimisers: the middle option
Optimisers attach per panel but feed a central inverter. You get per-panel shade handling and monitoring at lower cost than microinverters, while still having a central inverter that will need replacing eventually. For a partly shaded roof on a budget this is often the sensible answer.
How to decide
- One unshaded plane, simple roof → string inverter. Do not pay for shade tolerance you do not need.
- Any meaningful shading → microinverters or optimisers. This is where the money is genuinely recovered.
- Two or more roof directions → microinverters, or separate strings with an inverter that has multiple MPPT inputs.
- You want per-panel data → microinverters or optimisers. Useful for spotting a failure early.
Check how shaded your roof actually is → Google's imagery measures it, which beats guessing.
What this looks like in real cities
Measured rooftop data, spanning the range from fastest to slowest payback we have found:
| City | Sun hrs/yr | Rate | Payback |
|---|---|---|---|
| Honolulu, HI | 1,787 | 42.1¢ | 3.1 yrs |
| Silver Spring, MD | 1,481 | 18.3¢ | 8.8 yrs |
| Evansville, IN | 1,474 | 15.3¢ | 10.6 yrs |
| Winston-Salem, NC | 1,363 | 13.2¢ | 13.3 yrs |
| Gatineau, QC | 1,291 | 7.9¢ | 33.3 yrs |
Frequently asked
Are microinverters worth the extra cost?
On a shaded or multi-directional roof, usually yes. On a single unshaded plane the extra cost buys little beyond per-panel monitoring and a longer warranty.
What is the difference between optimisers and microinverters?
Optimisers condition each panel but still feed a central inverter; microinverters do the full DC-to-AC conversion at each panel. Optimisers cost less but keep a central point of failure.
Which lasts longer?
Microinverters carry 20-25 year warranties versus 10-15 for string inverters, but they sit on a hot roof rather than a cool garage wall, and replacing one means removing a panel.
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General information, updated 2026-08-22. Not financial, tax or engineering advice.