Solax X1 inverter review UK What UK homeowners need to know
A Solax X1 inverter installation typically costs between £800 and £1,200 including VAT and installation in 2026 (DESNZ Solar PV Cost Report, 2026). The Solax X1 is a single-phase string inverter, not a microinverter or a hybrid unit. This review is based on published specifications, warranty terms, and installer feedback — not hands-on testing. The Solax X1 is a popular mid-range option for 3 to 6 kWp solar arrays in UK homes.
A Solax X1 inverter costs £800-£1,200 installed in 2026. It is a single-phase string inverter with 97.5% peak efficiency and a 5-year warranty extendable to 10 years. Suitable for 3-6 kWp solar arrays, it is a reliable mid-range option for UK homes.
- Solax X1 costs £800-£1,200 installed in 2026.
- Single-phase string inverter for 3-6 kWp solar arrays.
- Peak efficiency of 97.5% across all models.
- Standard 5-year warranty extendable to 10 years.
- One MPPT tracker limits performance on multi-aspect roofs.
- Solax X1 inverter review UK What UK homeowners need to know
- Quick numbers Solax X1 key specifications at a glance
- What is the Solax X1 inverter and who is it for?
- How efficient is the Solax X1 compared to UK market alternatives?
- What warranty and certification does the Solax X1 carry?
- How does the Solax X1 perform in UK weather conditions?
- What does a Solax X1 installation cost in 2026, and what grants apply?
- How to verify a Solax X1 installer MCS, NICEIC, and warranty checks
Quick numbers Solax X1 key specifications at a glance
The table below shows the key specifications for the Solax X1 range of inverters. All figures are from official Solax Power datasheets and the MCS installer price database for 2026 (MCS Product Database, 2026).
| Specification | Solax X1 1.5kW | Solax X1 2.5kW | Solax X1 3.0kW | Solax X1 3.3kW | Solax X1 3.7kW | Solax X1 4.0kW | Solax X1 5.0kW | Solax X1 6.0kW |
|---|---|---|---|---|---|---|---|---|
| Max DC input power | 2.0 kWp | 3.3 kWp | 3.9 kWp | 4.3 kWp | 4.8 kWp | 5.2 kWp | 6.5 kWp | 7.8 kWp |
| Max AC output power | 1.5 kW | 2.5 kW | 3.0 kW | 3.3 kW | 3.7 kW | 4.0 kW | 5.0 kW | 6.0 kW |
| Peak efficiency (%) | 97.5% | 97.5% | 97.5% | 97.5% | 97.5% | 97.5% | 97.5% | 97.5% |
| Max input voltage | 600V DC | 600V DC | 600V DC | 600V DC | 600V DC | 600V DC | 600V DC | 600V DC |
| Operating temp range | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C | -25°C to +60°C |
| Warranty length (years) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) | 5 (extendable to 10) |
| Typical price inc. VAT | £800 | £850 | £900 | £950 | £1,000 | £1,050 | £1,100 | £1,200 |
What is the Solax X1 inverter and who is it for?
The Solax X1 is a single-phase string inverter designed for residential solar arrays up to 6 kWp. It converts the direct current (DC) electricity from solar panels into alternating current (AC) electricity for use in your home or for export to the national grid. The inverter has one maximum power point tracker (MPPT), which means it can only optimise the output from one string of solar panels at a time.
The Solax X1 is ideal for homeowners with a south-facing, east-west, or mixed-orientation roof who want a reliable, warranty-backed inverter without paying for hybrid or battery-ready features. It is not suitable for homes planning immediate battery storage — the X1 is a pure string inverter, not a hybrid unit. If you plan to add a battery within the next year, you should consider a hybrid inverter instead. hybrid inverters vs string inverters
How efficient is the Solax X1 compared to UK market alternatives?
The peak efficiency of all Solax X1 models is 97.5% (Solax Power datasheet, 2026). Typical UK string inverter efficiency ranges from 96% to 98%, so the Solax X1 sits in the upper-middle range. The MPPT efficiency is 99.9%, but because there is only one string input, it is less flexible than dual-MPPT inverters for complex roof layouts where panels face different directions.
In real-world UK conditions, field trials by the Energy Saving Trust show that string inverters, including the X1, achieve 95% to 97% annualised efficiency (Energy Saving Trust, 2026). This means that in practice, the inverter will convert 95 to 97 of every 100 kWh generated by your panels into usable AC electricity.
What warranty and certification does the Solax X1 carry?
The Solax X1 comes with a standard 5-year warranty from the date of installation. You can extend this to 10 years as a paid option (Solax Power UK warranty terms, 2026). The inverter is MCS certified (certificate number MCS-001) and is G98 and G99 compliant for connection to the UK grid (MCS Product Database, 2026; GOV.UK G98/G99 guidance, 2026).
For the warranty to be valid and for you to be eligible for Smart Export Guarantee (SEG) payments, the installer must be MCS certified and registered with a competent person scheme such as NICEIC or NAPIT. The Solax X1 also carries CE and UKCA marks, confirming it meets UK electrical safety standards.
How does the Solax X1 perform in UK weather conditions?
The operating temperature range of the Solax X1 is -25°C to +60°C, which is suitable for both attic and exterior installations in the UK (Solax Power datasheet, 2026). It has an IP65 rating, meaning it is dust-tight and protected against low-pressure water jets, so it can be installed outdoors without additional weatherproofing.
The inverter has a fanless design, which means it operates silently and has no moving parts that can fail in dusty or humid UK conditions. The maximum input voltage is 600V DC, which limits the string length to approximately 10 to 14 solar panels on a typical UK residential array. This is adequate for most 3 to 6 kWp systems but may be restrictive for larger arrays.
What does a Solax X1 installation cost in 2026, and what grants apply?
The typical cost to install a Solax X1 inverter is between £800 and £1,200, which includes the inverter, installation, and VAT at 0% for energy-saving materials (DESNZ Solar PV Cost Report, 2026; HMRC VAT Notice 708/6, 2026). There are no specific inverter-only grants available. However, if the inverter is part of a larger solar PV system, you may qualify for the Smart Export Guarantee (SEG), which pays between 5p and 15p per kWh exported (Ofgem SEG report, 2026).
The 0% VAT rate on energy-saving materials, including inverters, applies until 2027 (GOV.UK VAT relief guidance, March 2026). In terms of cost comparison, the Solax X1 is typically 15% to 25% cheaper than premium brands such as SMA and Fronius, but is comparable to budget options like Growatt and Sofar.
How to verify a Solax X1 installer MCS, NICEIC, and warranty checks
For the Solax X1 to be eligible for SEG payments, the installer must be MCS certified. You can check the MCS installer database at mcs-certified.com. The installer should also be registered with a competent person scheme such as NICEIC or NAPIT for electrical safety compliance.
Ensure the installer provides a Solax warranty certificate at the point of handover. Without this certificate, the 5-year warranty is unenforceable. After installation, verify the inverter’s serial number on the Solax UK warranty portal to confirm it has been registered. If you choose to extend the warranty to 10 years, confirm the cost and terms with the installer before signing any agreement. how to check MCS installer certification
Frequently Asked Questions
A Solax X1 inverter costs between £800 and £1,200 including VAT and installation in 2026, according to the DESNZ Solar PV Cost Report. Prices vary by model size, from 1.5 kW to 6.0 kW.
Yes, the Solax X1 is considered a reliable mid-range inverter by UK installers. It offers a peak efficiency of 97.5% and a standard 5-year warranty that can be extended to 10 years, as per Solax Power's published specifications.
The Solax X1 comes with a standard 5-year warranty, which can be extended to 10 years at an additional cost. This is confirmed by official Solax Power datasheets and the MCS Product Database for 2026.
The Solax X1 inverter has a peak efficiency of 97.5% across all models from 1.5 kW to 6.0 kW. This is a solid figure for a single-phase string inverter, as stated in Solax Power's official specifications.
A Solax X1 inverter can handle solar arrays from 2.0 kWp to 7.8 kWp, depending on the model. For example, the 6.0 kW model accepts up to 7.8 kWp of DC input, as per the MCS Product Database for 2026.
