Optimisers vs Microinverters: Which Do You Need?

If your roof has shading, panels on multiple orientations, or you simply want maximum performance from each panel, you'll encounter two options: power optimisers and microinverters. Both solve the same core problem in different ways. Here's a practical comparison.

The Problem They Both Solve

In a standard string inverter setup, solar panels are wired in series. The entire string's output is limited by the weakest-performing panel. If one panel is shaded, dirty, or faulty, every panel in that string underperforms.

Both optimisers and microinverters address this by allowing each panel to operate at its own optimal point, independent of the others.

Power Optimisers

How They Work

A power optimiser is a small DC-DC converter fitted behind each solar panel. It adjusts the voltage and current of that panel to extract maximum power, regardless of what other panels in the string are doing. The optimised DC power is then fed to a central string inverter, which converts it to AC for your home.

Think of it as each panel having its own personal trainer, while still sharing a gym (the central inverter).

Key Products

• SolarEdge — The dominant optimiser brand. Their system requires a SolarEdge inverter paired with SolarEdge optimisers.
• Tigo — An aftermarket optimiser that can be added to panels from any manufacturer and works with various string inverters.
• Huawei SUN2000 with optimisers — Huawei offers a similar paired system.

Pros

• Lower cost than microinverters (£30–50 per panel vs £50–80)
• Panel-level monitoring shows each panel's individual performance
• Rapid shutdown capability (a safety feature increasingly required)
• Central inverter is easier to service (located indoors, accessible)
• Well-proven technology with millions of installations worldwide

Cons

• Still has a central inverter that can fail (single point of failure)
• Some systems are proprietary — SolarEdge optimisers only work with SolarEdge inverters
• The central inverter still limits maximum system output

Microinverters

How They Work

A microinverter is a small inverter fitted behind each solar panel. It converts DC to AC right at the panel, so only AC power travels through your wiring to the consumer unit. There is no central string inverter at all.

Each panel is a completely self-contained generating unit.

Key Products

• Enphase IQ7/IQ8 — The market leader in microinverters. Mature, reliable, widely available in the UK.
• Hoymiles — Growing Chinese brand with competitive pricing, popular for smaller systems and retrofit.
• AP Systems — Another established option, particularly in commercial settings.

Pros

• No single point of failure — if one microinverter fails, only that panel is affected
• Best performance in heavy shading — each panel is truly independent
• Scalable — add panels one at a time without inverter capacity concerns
• No high-voltage DC on your roof (AC only), which some consider safer
• Panel-level monitoring included
• Long warranties (Enphase offers 25 years)

Cons

• Higher cost per panel (£50–80 each vs £30–50 for optimisers)
• Each microinverter is on the roof, making replacement more involved (scaffolding needed)
• Slightly lower peak efficiency than the best central inverters
• More points of potential failure (one device per panel vs one central device)

Head-to-Head Comparison

GivEnergy All-in-One 5kW Hybrid Inverter

£1,200

rated power kw

5

max pv input kw

7.5

mppt channels

2

battery voltage v

48V

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When Do You Need Either?

You Need Optimisers or Microinverters If:

• Your roof has shading from trees, chimneys, neighbouring buildings, or other obstructions
• Panels face multiple directions (e.g., some south, some east) — each orientation performs differently at different times
• You want panel-level monitoring to diagnose individual panel issues
• You may expand the system later — microinverters make this especially easy

A Standard String Inverter Is Fine If:

• Your roof has no significant shading throughout the year
• All panels face the same direction on a single roof slope
• You want the lowest upfront cost
• Your system is a straightforward, single-string layout

Tigo TS4-A-O Power Optimiser

£38

type

DC optimiser

compatibility

Any inverter

monitoring

Module-level

max input power w

700

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Cost Impact on a Typical System

For a 10-panel (4kW) system:

*Microinverters replace the string inverter entirely, so the comparison depends on the specific products chosen. In some cases, a microinverter system is barely more expensive than a string inverter system.

Which Should You Choose?

Choose optimisers if:

• You have moderate shading (1–3 panels affected)
• You want a balance of performance and cost
• Your installer is experienced with SolarEdge or similar systems

Choose microinverters if:

• You have significant shading across multiple panels
• Your panels face two or more different directions
• You want the longest warranty without inverter replacement
• You may want to add panels in the future
• Safety (no high-voltage DC) is a priority

Choose a standard string inverter if:

• Your roof is unshaded and panels face one direction
• You want the lowest upfront cost
• You're comfortable with the standard approach that covers 70%+ of UK installations

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