String Inverter vs Microinverter vs Power Optimiser
These three inverter architectures decide how each panel's DC electricity becomes usable AC — and how well your system copes with shade. This is a focused decision guide. For the wider picture see our inverter comparison and specific solar inverter brand picks.
Quick Answer
A string inverter is one central unit for a whole string of panels: cheapest, but the weakest or shaded panel can drag down the rest. A power optimiser (SolarEdge) adds a small device per panel feeding a central inverter, fixing shade losses with per-panel monitoring. A microinverter (Enphase) converts DC to AC at each panel, with no single point of failure. Unshaded Irish roofs suit string; shaded or multi-pitch roofs suit optimisers or micros.
How String, Optimiser, and Microinverter Architectures Work
All three turn the DC electricity your panels produce into the AC electricity your home and grid use. The difference is where that conversion happens and how each panel is managed. That single design choice drives cost, shade tolerance, monitoring detail, and what happens when a component fails.
String inverter (central)
Panels are wired in series into a "string" that runs down to one central inverter, typically mounted near your consumer unit. It is the simplest and cheapest architecture. Because the panels share a circuit, the string current is limited by the weakest or most shaded panel, so output across the whole string can drop when one panel underperforms. It works best on a single, unshaded roof face. Common brands in Ireland include Huawei, Solis, and GoodWe.
Power optimiser (DC, per panel + central inverter)
A small DC optimiser is fitted to each panel and conditions that panel's output before sending it to one central inverter. This mitigates shading losses — a shaded panel no longer drags the whole string — and unlocks per-panel monitoring, while keeping a single central inverter. It is the middle ground on cost and complexity. SolarEdge is the best-known optimiser system, typically with a 12-year inverter warranty and a 25-year optimiser warranty.
Microinverter (AC, per panel)
A microinverter sits under each panel and converts DC to AC right at the panel, so there is no central inverter and no single point of failure — if one unit fails, only that panel is affected. Micros give the most granular per-panel monitoring and suit shaded, complex, or multi-orientation roofs. They typically cost around 30–50% more than a string setup. Enphase is the leading brand, with the IQ8 range carrying a 25-year warranty.
String vs Micro vs Optimiser: Side-by-Side Comparison
The table below compares the three architectures across the factors that matter most for an Irish home: cost, how each handles shade, monitoring, warranty, and what happens when something fails.
| Feature | String Inverter | Power Optimiser | Microinverter |
|---|---|---|---|
| Where DC→AC happens | Central inverter | Central inverter (DC optimised per panel) | At each panel |
| Example brand | Huawei, Solis, GoodWe | SolarEdge | Enphase (IQ8) |
| Relative cost | Lowest | Middle ground | Highest (around 30–50% more) |
| Shading performance | Weakest panel limits the string | Per-panel, shade losses mitigated | Per-panel, shade isolated |
| Per-panel monitoring | No (system-level only) | Yes | Yes |
| Single point of failure | Yes (central inverter) | Central inverter (panels keep monitoring) | No |
| Failure impact | Whole string stops | Affected panel reduced, rest continues | Only the affected panel stops |
| Warranty (typical) | Around 10–12 years | 12yr inverter, 25yr optimiser | 25 years |
| Best for | Simple, unshaded single-pitch roof | Partial shading, multiple orientations | Shaded, complex, multi-orientation roofs |
SolarEdge vs Enphase: Optimiser vs Microinverter Architecture
SolarEdge and Enphase are the two names most often weighed against each other when a roof needs panel-level electronics. Both deliver per-panel monitoring and strong shade tolerance, but they get there with fundamentally different architectures.
SolarEdge (optimiser)
Keeps a single central inverter and adds a DC optimiser to each panel. The conversion to AC still happens centrally, so there is one inverter to service or eventually replace — typically warrantied around 12 years, with the optimisers themselves rated for 25 years. A practical middle ground when you want shade mitigation and per-panel data without paying full microinverter prices.
Enphase (microinverter)
Replaces the central inverter entirely with a microinverter under each panel, converting to AC at source. There is no single point of failure, the architecture is modular and easy to expand panel by panel, and the IQ8 range carries a 25-year warranty. Usually the priciest option, and the strongest fit for genuinely complex or multi-orientation roofs.
For a full brand-by-brand breakdown including string and hybrid options, see our solar inverter brands guide, or step back to the wider inverter comparison.
What This Means for Irish Homes
In Ireland, hybrid string inverters dominate residential installations because most homes pair solar with a battery and a single central unit keeps costs down. Optimisers and microinverters are chosen mainly for shaded, dormer, and multi-pitch roofs — all common on older Irish housing stock — where a plain string would lose output to overshadowing.
Ireland's mild, diffuse, often-cloudy climate means a lot of generation comes from soft, scattered light rather than direct sun. On a clean, unshaded south-facing roof a string inverter captures this perfectly well. Where chimneys, dormers, or neighbouring trees cast partial shade, per-panel architectures (optimisers or micros) protect more of that diffuse-light yield.
- SEAI grant: The SEAI solar PV grant covers the panel (PV) portion of a domestic install and is capped at €1,800. It does not change which inverter architecture you pick — that is a roof and budget decision.
- 0% VAT: Domestic solar installations qualify for 0% VAT in Ireland, which lowers the headline cost of all three architectures.
- CEG export: Under the Clean Export Guarantee you are paid for surplus electricity sent to the grid, so squeezing more from a shaded roof with optimisers or micros can improve export earnings.
- ESB Networks: Your installer registers the system with ESB Networks (NC6/NC7 process) regardless of architecture. All three connect through the same export metering.
New to solar overall? Start with our solar panels guide for the full picture before narrowing down the inverter.
Which Should You Choose?
The right architecture comes down to your roof, your shading, and your budget. Match your situation to the scenarios below.
Single, unshaded south-facing roof
String inverter (Huawei, Solis, GoodWe)
The simplest and most cost-effective choice. With no shading and one orientation, a string setup captures full output without paying for per-panel electronics.
Partial shading or panels facing two directions
Power optimiser (SolarEdge)
Per-panel optimisation stops a shaded chimney-side panel from dragging the rest, while keeping a single central inverter and a lower price than micros.
Complex dormer / multi-pitch roof, want max resilience
Microinverter (Enphase IQ8)
No single point of failure, the best per-panel monitoring, easy expansion, and a 25-year warranty. The strongest fit for awkward Irish roofs, at the highest cost.
Tightest budget, simple roof
String inverter
If shading is not an issue, the extra spend on optimisers or micros rarely pays back. Put the saving toward more panels or a battery instead.
Frequently Asked Questions
What is the difference between a string inverter, a microinverter, and a power optimiser?
A string inverter is one central unit that converts DC to AC for a whole string of panels, so the weakest or shaded panel can limit the rest. A power optimiser adds a small DC device to each panel that feeds a central inverter, mitigating shade and adding per-panel monitoring. A microinverter converts DC to AC at each individual panel, with no single point of failure.
Is a microinverter worth it for an Irish home?
For a simple, unshaded south-facing roof, usually not. A string inverter is cheaper and performs well in Ireland's diffuse light. Microinverters earn their roughly 30 to 50 percent higher cost on shaded, dormer, or multi-orientation roofs, where per-panel conversion protects output and gives panel-level monitoring.
SolarEdge or Enphase for a shaded roof?
Both handle shading well. SolarEdge optimisers keep a single central inverter (12-year inverter warranty, 25-year optimisers) and cost less, making them a good middle ground. Enphase microinverters convert at each panel with no single point of failure and a 25-year warranty, which suits genuinely complex roofs but costs more.
Does the inverter architecture affect my SEAI grant?
No. The SEAI solar PV grant applies to the panel (PV) portion and is capped at 1,800 euro regardless of whether you use a string inverter, optimisers, or microinverters. Domestic solar also qualifies for 0% VAT. The architecture choice is driven by your roof and budget, not the grant.
What happens if my inverter fails?
With a string inverter, a central inverter failure stops the whole system until it is replaced. With SolarEdge, a central inverter still exists but optimisers keep monitoring panels; an affected panel is reduced rather than stopping everything. With Enphase microinverters there is no single point of failure, so only the panel with the failed unit goes offline.
Related Guides
Inverter Guide
Comparing string, micro, and hybrid inverters.
Solar Inverter Brands
Best solar inverter brands in Ireland ranked by efficiency, warranty, and value.
AC vs DC Coupled Batteries
Retrofit vs new-install battery coupling and efficiency.
Equipment Guide
Panels, inverters, batteries, and what to choose.
Sources
- SEAI — Solar Energy for the Home — seai.ie
- SolarEdge — Residential Solutions — solaredge.com
- Enphase — Microinverter Technology — enphase.com
- ESB Networks — Generator Connections — esbnetworks.ie
Last updated: June 2026
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
John Rooney is the founder of Solar Info and has been covering the Irish solar energy market since 2023. He fact-checks all content against official SEAI data and maintains relationships with SEAI-registered installers across Ireland.
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