A string inverter costs roughly £1,000 less than an equivalent microinverter system for a typical UK home, but the lifetime savings from microinverters can close that gap within 10 years.
For a typical 4 kWp solar panel system, a string inverter costs around £800–£1,200, while adding microinverters increases the total system price by £1,500–£2,500 (Energy Saving Trust, 2026). The higher upfront cost of microinverters is offset by lower maintenance and higher energy yield over 25 years. Payback period for microinverters typically ranges from 8–12 years, depending on roof orientation and shading (MCS register, 2026).
String inverters cost £800-£1,200 for a 4 kWp system, while microinverters add £1,500-£2,500. Microinverters last 20-25 years and handle shading better, with a payback period of 8-12 years. Compare your roof's shading to decide.
- String inverters cost £800-£1,200 for a 4 kWp system, microinverters £2,300-£3,700.
- Microinverters last 20-25 years, outlasting string inverters by up to 15 years.
- Shading on one panel cuts string inverter output by 30%, not microinverters.
- Microinverter payback period is 8-12 years, depending on roof orientation.
- Replace a string inverter once; microinverters may need no replacement in 25 years.
- A string inverter costs roughly £1,000 less than an equivalent microinverter system for a typical UK home, but the lifetime savings from microinverters can close that gap within 10 years.
- How a string inverter works in a solar panel system
- How a microinverter works on each solar panel
- Quick numbers cost, efficiency, and lifespan comparison
- Which system saves more money over 25 years string vs microinverter
- Eligibility and certification what installers and equipment need
- How to choose between string and microinverter for your home
How a string inverter works in a solar panel system
A string inverter is a single central unit that connects to all solar panels on one or more series circuits, called strings. It converts the direct current (DC) electricity from all panels into alternating current (AC) for use in your home. If one panel is shaded or fails, it reduces the output of the entire string that panel is connected to. String inverters are simpler, cheaper, and easier to replace than microinverters, but they are less efficient in partial shade (Energy Saving Trust, 2026).
How a microinverter works on each solar panel
A microinverter is a small unit attached to each individual solar panel, converting DC to AC at the point of generation. Because each panel operates independently, shading or failure of one panel does not affect the others, maximising energy harvest. Microinverters allow for easier system expansion and monitoring of individual panel performance (Energy Saving Trust, 2026).
Quick numbers cost, efficiency, and lifespan comparison
| Feature | String Inverter | Microinverter |
|---|---|---|
| Upfront cost (4 kWp system) | £800–£1,200 | £2,300–£3,700 |
| Typical lifespan | 10–15 years | 20–25 years |
| Warranty period | 5–10 years | 20–25 years |
| Efficiency in full sun | 97–99% | 95–97% |
| Efficiency with 20% shading | Drops to ~70% | Remains ~95% |
| Replacement cost (per unit) | £800–£1,200 | £150–£250 per panel |
Data from Energy Saving Trust, 2026 and MCS register, 2026. Shading efficiency figures based on Ofgem typical UK shading scenarios, 2026.
Which system saves more money over 25 years string vs microinverter
For a south-facing, unshaded roof, a string inverter system saves roughly £200–£400 more over 25 years due to lower upfront cost (Energy Saving Trust, 2026). For a roof with partial shading (e.g., a chimney or tree), microinverters can harvest 5–15% more energy annually, making them the cheaper option long-term. The break-even point for microinverters on a shaded roof is typically 10–14 years, after which they generate higher savings (DESNZ, 2026).
Eligibility and certification what installers and equipment need
All solar panel systems in the UK must be installed by an MCS-certified installer to qualify for the Smart Export Guarantee (SEG) and any government grants (MCS register, 2026). Microinverter systems require individual MCS certification for each unit, while string inverters are certified as a single system. Both types must comply with G99 or G100 grid connection standards, verified by the installer (GOV.UK, 2026).
How to choose between string and microinverter for your home
Choose string inverters if your roof is south-facing, unshaded, and you want the lowest upfront cost. Choose microinverters if your roof has shading, multiple orientations, or you plan to expand the system later (Energy Saving Trust, 2026). Consider future battery storage: string inverters may require a separate battery inverter, while some microinverters integrate with AC-coupled batteries. Solar battery storage options for UK homes Smart Export Guarantee guide for homeowners
Frequently Asked Questions
A string inverter is a single unit for all panels, costing £800-£1,200, while microinverters are per-panel devices costing £2,300-£3,700 for a 4 kWp system. Microinverters handle shading better and last longer, according to the Energy Saving Trust (2026).
Microinverters are better for shaded roofs or complex orientations, as each panel works independently. For unshaded south-facing roofs, a string inverter is more cost-effective, says the Energy Saving Trust (2026).
A microinverter system for a 4 kWp array costs £2,300-£3,700, roughly £1,500-£2,500 more than a string inverter setup. This estimate comes from the MCS register (2026).
Yes, microinverters typically last 20-25 years, compared to 10-15 years for string inverters, according to the Energy Saving Trust (2026). Their warranty often matches the solar panel lifespan.
Yes, some systems use a string inverter for most panels and microinverters on shaded ones, but this adds complexity. The Energy Saving Trust recommends consulting an MCS-certified installer for hybrid setups.
