String inverters are the simplest and usually cheapest option, and they work well on unshaded roofs with one or two orientations. Microinverters and power optimizers cost more but handle shade, partial snow cover and complex roofs better, and they let you monitor each panel. The right choice depends on your roof's layout, how much shade it gets, and whether you plan to expand or add a battery.
Key takeaways
- Every grid-tied solar system needs an inverter to turn the panels' direct current (DC) into the alternating current (AC) your home uses.
- String inverters: lowest cost, one central box, but one shaded or snow-covered panel can drag down the whole string.
- Microinverters: one small inverter per panel, best shade tolerance, easy expansion, higher cost.
- Power optimizers: panel-level electronics feeding a central inverter, a middle ground.
- Check how each option handles battery storage before you commit.
How each system works
String inverters
Panels are wired in series into one or more "strings," and each string feeds a single central inverter, usually mounted near your electrical panel or meter. Because the panels are in series, the current through the string is limited by its weakest panel. Shade on one panel, or snow left on the bottom row, can reduce output across the whole string.
Modern string inverters have multiple inputs, called MPPTs (maximum power point trackers), so panels on different roof faces can be on separate strings. That reduces, but doesn't eliminate, the mismatch problem.
Microinverters
A small inverter mounts under each panel, and each converts power independently. Output from one panel doesn't affect another. AC wiring runs from the roof to your panel. Most microinverter systems include per-panel monitoring through an app.
Power optimizers
An optimizer, a DC-to-DC converter, mounts under each panel and conditions its output before sending it to a central string inverter. You get panel-level optimization and monitoring, but conversion to AC still happens in one central box.
Side-by-side comparison
| Feature | String inverter | Microinverters | Power optimizers |
|---|---|---|---|
| Upfront cost | Lowest | Highest | Middle |
| Shade and partial snow | Most affected | Least affected | Well handled |
| Complex roofs (many faces) | Fair, with multiple MPPTs | Excellent | Excellent |
| Panel-level monitoring | Usually no | Yes | Yes |
| Electronics on the roof | None | One per panel | One per panel |
| Typical warranty (approx.) | ~10–12 years, sometimes extendable | Often ~20–25 years | Optimizers ~20–25; inverter ~12 or more |
| Expansion | May need a new or larger inverter | Easy, add panels with micros | Moderate |
| Battery pairing | Hybrid models available | Usually an AC-coupled battery | Hybrid central inverters available |
Warranty terms vary by manufacturer and model. Check the actual datasheet and warranty document.
Canadian considerations
Snow behaves like shade
In Canada, partial snow cover is a big deal. After a storm, the top of the array often clears before the bottom. With a string inverter, a few snow-covered panels can hold back the whole string. Microinverters and optimizers let the clear panels produce fully. Over a winter, that difference is real but modest, because winter output is a small share of annual production anyway. See our winter guide.
Cold-weather voltage
Panel voltage rises in cold weather. For string systems, designers must make sure string voltage on the coldest expected morning stays within the inverter's limit. A competent Canadian installer accounts for this. It's a quiet sign of good design.
Rapid shutdown
The Canadian Electrical Code includes requirements for rooftop systems to reduce voltage on the roof quickly in an emergency, which helps firefighters. Microinverters and optimizers typically meet this inherently. String systems may need additional rapid-shutdown devices. Your installer and local inspector will confirm what applies.
Where the electronics live
A central string inverter sits indoors or in a sheltered spot, which makes it easy to service or replace. Microinverters and optimizers live under the panels and go through every freeze-thaw cycle. Their long warranties reflect confidence in that, but if one fails, someone has to go on the roof. Ask whether the installer's workmanship warranty covers that labour.
Which should you choose?
A string inverter often makes sense if: - Your roof is simple, with one or two faces, and is largely unshaded - You want the lowest upfront cost - You're pairing with a battery and want a single hybrid inverter
Microinverters often make sense if: - You have shade from trees, chimneys or dormers - Your roof has several faces or orientations - You plan to add panels later - You want detailed per-panel monitoring
Optimizers often make sense if: - You want panel-level performance but prefer a central inverter - You want a hybrid inverter for battery storage with panel-level optimization
Your system size and roof layout should drive the choice, not the brand an installer happens to stock.
Batteries and backup
If storage is in your plans, discuss it now:
- DC-coupled: the battery connects on the DC side through a hybrid inverter. It's efficient and common with string or optimizer systems.
- AC-coupled: the battery has its own inverter and connects on the AC side. It's common with microinverters and for adding storage to an existing system.
Either can work. What matters is whether the setup provides backup during an outage. Many grid-tied systems shut down when the grid goes down unless they're specifically designed for backup.
Lifetime costs
String inverters commonly need replacing once over a 25- to 30-year system life, which can cost a couple of thousand dollars or more. Microinverters and optimizers have longer warranties but more individual parts. Over the long run the total costs can end up closer than upfront prices suggest. Include inverter replacement in your payback math.
Frequently asked questions
Do microinverters produce more electricity?
On shaded or complex roofs, usually yes, because each panel works independently. On a simple, unshaded, single-orientation roof, the difference from a well-designed string system is often small.
How long do solar inverters last?
String inverters commonly last around 10 to 15 years. Microinverters and optimizers often carry warranties of 20 to 25 years. Real-world life depends on the product, heat and installation quality.
Can I mix panels on different roof faces with a string inverter?
Yes, if the inverter has enough independent inputs (MPPTs) to keep each orientation on its own string. Mixing orientations within one string causes losses.
The bottom line
There's no single best inverter. There's the best one for your roof. Simple, sunny roofs do well with a string inverter. Shaded, complex or expandable setups benefit from microinverters or optimizers. Ask your installer to explain their choice for your specific roof and show you the warranty terms. For background terms, see our glossary, FAQ and solar overview.
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