Microinverters vs string inverters

Every grid-tied solar system needs an inverter to turn the panels' direct current (DC) into the alternating current (AC) your home uses. There are three common ways to do it, and the choice affects how the system handles shade, how much detail you see in monitoring, and what it costs.

The three setups

String inverter

Panels are wired together in one or more series circuits called strings. All of that DC power runs to one inverter, usually mounted near your electrical panel or meter.

• Lowest equipment cost for a simple, unshaded roof
• One box to service or replace
• The whole string tends to be limited by its weakest panel, so shade on one panel can pull down the output of others
• Monitoring usually shows the whole system, not each panel

String inverter with optimizers

A small power optimizer sits under each panel. It adjusts each panel's output so that shade or dirt on one panel has much less effect on the rest. A central inverter still does the DC to AC conversion.

• Better shade tolerance than a plain string
• Panel-level monitoring
• More parts on the roof, at a higher cost than a plain string

Microinverters

A small inverter sits under each panel and converts power to AC right there. Each panel works independently.

• Best fit for roofs with partial shade, several roof faces or different orientations
• Panel-level monitoring
• Easy to add panels later
• Usually the highest equipment cost
• More electronics on the roof, which are harder to reach if one fails

How they compare

Warranty terms vary by brand. For example, one major optimizer brand offers 25 years on optimizers and 12 years standard on its inverter, while a major microinverter brand offers 25 years.

Shading is the deciding factor

On a clear, south-facing roof with no shade, a plain string inverter often gives the best value. The production gain from panel-level electronics is small when nothing blocks the sun.

When a chimney, dormer, tree or neighbouring building shades part of the roof at certain times of day or year, optimizers or microinverters can recover a meaningful share of lost production. They also make it practical to use two or three roof faces at different angles. See our guide on shading and solar.

Rapid shutdown rules in Canada

The Canadian Electrical Code includes a rapid shutdown requirement for solar on buildings (Rule 64-218). In the 2018 edition, circuits more than 1 metre from the array must drop to no more than 30 volts within 30 seconds of shutdown being triggered. On a single-family home, the switch that starts the shutdown goes at the utility meter location. The aim is to make the roof and building safer for anyone working on them, including firefighters.

Microinverters meet this naturally, because high-voltage DC never leaves the panel. Optimizer systems include a shutdown function. A plain string system needs added equipment, such as module-level shutdown devices, to comply when DC wiring runs across or into the house.

Provinces adopt code editions on their own schedules and can add local changes. Your installer and the electrical inspector will confirm what applies to you. Rapid shutdown equipment should be in the quote, not an add-on later.

Lifespan and replacement

Panels commonly last 25 years or more. A single string inverter will often need replacing once in that time. Microinverters and optimizers have longer warranties, but a failed unit means a roof visit. Ask installers what a replacement costs and who pays for labour under warranty.

Monitoring

Panel-level monitoring makes it easy to spot one underperforming panel, a shade problem or a failed unit. System-level monitoring still shows whether production is on track overall. See solar monitoring and what to watch.

Battery compatibility

All three can work with a home battery, but the route differs.

• Hybrid string inverters can connect a battery on the DC side, often a tidy option when you install solar and battery together.
• Microinverter systems usually pair with an AC-coupled battery that has its own inverter. This is also the common way to add a battery to an existing system.
• Optimizer systems usually pair with the same brand's hybrid inverter and battery.

If you think you may add a battery, tell installers now so they can choose compatible equipment. See batteries explained.

Which to choose

• Simple, unshaded, single-face roof on a budget: string inverter.
• Some shade or two roof faces, and you want panel monitoring: optimizers or microinverters.
• Complex roof, heavy partial shade, or plans to expand: microinverters are usually the easiest fit.

Next step

Check your roof to see how your roof's direction and shade affect output, then compare equipment across quotes with our quote checker.

Common questions

Are microinverters better than a string inverter?

On shaded or multi-face roofs they usually produce more and offer panel-level monitoring. On a clear south-facing roof a string inverter often gives better value.

Do I need rapid shutdown for solar in Canada?

The Canadian Electrical Code requires rapid shutdown for most solar systems on buildings. Your installer and electrical inspector will confirm which code edition and requirements apply in your province.

How long do solar inverters last?

String inverters often carry 10 to 12 year warranties and may need replacing once during a panel's life. Many microinverters and optimizers carry 25-year warranties.

Can I add a battery to a microinverter system?

Yes, usually with an AC-coupled battery that has its own inverter. Ask your installer which batteries are compatible with your equipment.

Sources

• IAEI Magazine: 2018 CE Code changes, rapid shutdown (Rule 64-218)
• Nova Scotia Power: Bulletin B-64-200, solar photovoltaic installations
• Portlandia Electric Supply: Enphase vs SolarEdge 2026