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 |
| Richmond, CA | 1,815 | 31.2¢ | 8.8 yrs |
| Rock Springs, WY | 1,844 | 12.1¢ | 10.9 yrs |
| Hereford, West Midlands | 1,014 | 26.1¢ | 12.9 yrs |
| Gatineau, QC | 1,291 | 7.9¢ | 33.3 yrs |
Frequently asked
Are microinverters worth the extra cost?
They earn their premium on complex or partly shaded roofs, where per-panel control recovers output a string inverter would lose. On a simple, unshaded, single-aspect roof the advantage is much smaller and a string inverter is usually better value. The roof decides this, not the brand.
What is the difference between optimisers and microinverters?
Optimisers condition each panel's output but still feed a central inverter; microinverters convert to AC at each panel with no central unit. Both give per-panel monitoring and shade tolerance. Optimisers keep one inverter to replace later; microinverters spread that risk across many smaller units mounted on the roof.
Which lasts longer?
Microinverters typically carry longer warranties, often twenty to twenty-five years, against ten to twelve for a string inverter. That does not automatically make them cheaper overall, since replacing one accessible string inverter can cost less than replacing several microinverters mounted underneath panels up on the roof.
Related guides
General information, updated 2026-08-22. Not financial, tax or engineering advice.