Which is better: string or micro inverter?

Depends on your roof. Unshaded, single-direction: string inverter (cheaper, simpler). Partially shaded or multi-direction: micro-inverters (each panel independent). Moderate shading: string + optimisers (SolarEdge — middle ground).

Are micro-inverters worth the extra cost?

If you have shading: yes — they recover 10–25% of otherwise lost output, paying for themselves within 5–10 years. If you have NO shading: the extra cost (£500–£1,800) provides panel-level monitoring and longer warranty, but no output benefit.

Do micro-inverters last longer than string inverters?

Yes — micro-inverters last 20–25 years (Enphase warrants 25 years). String inverters last 10–15 years and need replacing once during the panel lifespan. Micro-inverters avoid this replacement cost but cost more upfront.

Can I add a battery with micro-inverters?

Yes, but differently. Micro-inverter systems need an AC-coupled battery (connects on the AC side after conversion). String/hybrid inverter systems use DC-coupled batteries (more efficient). Both work — AC coupling is slightly less efficient (1–2% loss) but fully functional.

String Inverter vs Micro Inverter: Which Is Better?

Last updated: 18 March 2026

Independently written

String inverter mounted on wall — one central unit for all panels — String inverter (one box, all panels) vs micro-inverters (one per panel). Both have their place.

Which is better: string inverter or micro-inverter?

String inverters (£500–£1,000) connect all panels in series to one central unit — cheapest and simplest, but one shaded panel reduces the entire string's output. Micro-inverters (£1,000–£2,800) attach to each panel individually — more expensive but each panel operates independently, ideal for partial shading. For unshaded, single-direction roofs: string inverter. For shaded or multi-direction roofs: micro-inverters. A third option — string inverter + optimisers (£800–£1,500) — offers a middle ground.

Full Comparison

| Feature | String Inverter | Micro-Inverters | String + Optimisers | |---------|----------------|----------------|--------------------| | Cost (10 panels) | £500–£1,000 | £1,000–£2,800 | £800–£1,500 | | Location | Wall-mounted (garage/utility) | On back of each panel (roof) | String inverter on wall + optimisers on roof | | Shading handling | Poor (weakest panel limits all) | Excellent (each independent) | Good (each optimised but still one inverter) | | Monitoring | System-level only | Panel-level | Panel-level | | Lifespan | 10–15 years | 20–25 years | 10–15 years (inverter) + 25 years (optimisers) | | Warranty | 5–10 years | 25 years | 5–10 years (inverter) + 25 years (optimisers) | | Maintenance | One unit to replace | Multiple units on roof | One inverter to replace | | Efficiency | 96–98% | 96–98% | 97–99% (MPPT per panel) | | Best for | Unshaded, single direction | Shaded, complex roofs | Moderate shading | | Market leader | GivEnergy, Solis | Enphase | SolarEdge |

Source: Inverter manufacturer specifications; installer recommendations.

String inverter energy flow — all panels feed one central unit — String: all panels → one inverter. Micro: each panel → its own inverter. Different architectures.

When to Choose a String Inverter

Your roof is UNSHADED — no chimneys, trees, or buildings casting shadows on your panels
All panels face the SAME DIRECTION — single south, east, or west slope
Budget is a priority — string inverters cost 50–65% less than micro-inverters
You want battery readiness — GivEnergy hybrid inverters are string-based and include battery management
System is simple — standard 10-panel south-facing roof is textbook string inverter territory
You accept one-unit maintenance — the single inverter will need replacing at 10–15 years (£800–£1,500)

When to Choose Micro-Inverters

Your roof has PARTIAL SHADING — chimney shadow, tree shade, neighbouring building shade
Panels face MULTIPLE DIRECTIONS — east-west split, or panels on two different roof slopes
You want PANEL-LEVEL MONITORING — see exactly what each panel produces (diagnose issues easily)
You value LONGEVITY — micro-inverters last 20–25 years vs 10–15 for string (fewer replacements)
You want 25-YEAR WARRANTY — Enphase micro-inverters come with 25-year warranties as standard
Future expansion is likely — adding individual panels is easier with micro-inverters (no string matching required)
You want MAXIMUM SAFETY — micro-inverters reduce DC voltage to safe levels at the panel (no high-voltage DC on the roof)

Shading impact — micro-inverters prevent one shaded panel affecting all others — If you have shading: micro-inverters prevent one problem panel from dragging down the rest.

The Middle Ground: String + Optimisers (SolarEdge)

SolarEdge offers a popular middle ground: - One string inverter (wall-mounted) - Individual optimisers on each panel (£30–£50 per panel) - Each panel is individually optimised for maximum output - Panel-level monitoring included - SafeDC feature reduces voltage when system shuts down (firefighter safety)

Cost: £800–£1,500 total (between pure string and micro-inverters) Best for: Moderate shading where micro-inverters feel like overkill but standard string is not enough

SolarEdge vs Enphase: - SolarEdge: one central inverter + optimisers. Cheaper. But the central inverter still has a 10–15 year lifespan. - Enphase: no central inverter. More expensive. But nothing to replace at 10–15 years.

Source: SolarEdge and Enphase product comparison.

All three inverter types deliver positive returns — choose for your roof — All three options deliver strong returns. The right choice depends on your roof, not on which is 'best' overall.

Financial Impact of Choosing Wrong

Choosing a string inverter on a shaded roof: - Output loss from shading: 10–25% (£70–£175/year) - Over 25 years: £1,750–£4,375 lost - Micro-inverter premium: £500–£1,800 - Net cost of wrong choice: £0–£2,575 lost (micro-inverters would have paid for themselves)

Choosing micro-inverters on an unshaded roof: - No shading benefit (micro-inverters recover nothing because there is nothing to recover) - Extra cost: £500–£1,800 wasted on unnecessary technology - But: you get panel-level monitoring and 25-year warranty (some value) - Net cost of wrong choice: £300–£1,500 overspent (could have used a string inverter)

The lesson: Shading assessment during the site survey is CRITICAL. A good MCS installer will recommend the right inverter type based on your specific roof. If they recommend micro-inverters, ask them to show you the shading analysis.

Source: Shading loss calculations; inverter cost comparison.

Installer assessing shading — the key factor in inverter choice — Your installer's shading assessment determines the right inverter type — trust their analysis.

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