The comparison in 2026
JA Solar and LONGi are the two largest Chinese tier-1 panel manufacturers and dominate the UK commercial farm install market. Both produce comparable 540W modules at similar pricing. The differences matter for long-term economics and warranty positioning.
Both manufacturers are 2026 Kiwa PVEL Top Performers; the tests that separate specific models on an agricultural roof are on the solar panel comparison for farm roofs.
Detailed comparison
Module specifications. JA Solar JAM72S30 540W: 21.7% efficiency, 30-year linear performance warranty at 84.8% (0.55%/yr degradation), 12-year product warranty. LONGi Hi-MO LR5-72HPH-540M: 21.4% efficiency, 30-year linear performance warranty at 84.8% (0.45%/yr degradation), 15-year product warranty. Price. JA Solar 540W: £85-£95 landed UK in 2026 (slightly cheaper). LONGi 540W: £88-£100 landed UK in 2026 (slight premium). On a 200 kW install with 370 panels, the price differential is £1,000-£2,000 — small relative to total project cost. Long-term performance. JA Solar degradation rate 0.55%/yr vs LONGi 0.45%/yr. Over 25 years, the LONGi panels retain approximately 2.5% more capacity than equivalent JA Solar panels. For a 200 kW install generating 180,000 kWh year-one, the cumulative difference over 25 years is approximately 56,000 kWh — worth approximately £14,000 in cumulative generation value. Warranty terms. JA Solar 12-year product warranty vs LONGi 15-year product warranty. The 3-year additional product cover on LONGi is material — if a panel develops a manufacturing defect in year 13, JA Solar customers pay for replacement; LONGi customers don't. Recommendation. For most UK farm installs in 2026: LONGi for the longer warranty and slower degradation; JA Solar for the slightly lower upfront cost.
How to decide for your specific install
The right choice depends on the specifics of your farm: roof geometry; load profile; capital sensitivity; future expansion plans; long-term operational priorities. Ask for multiple specification scenarios in the feasibility study where the choice is material. Send an installer your half-hourly meter data and building dimensions and ask for a desk feasibility study, including specification recommendations with clear rationale.
Common questions
What do you typically recommend?
Depends on the specifics of the site. Our default approach is documented in the comparison above; alternative scenarios should be modelled where the project requirements suggest different specification choices.
How material is the difference in practice?
Most specification differences sit at the margin of project economics — typically 2-10% impact on overall 25-year NPV. The fundamental decision (whether to install PV at all) is far more material than the specification choice within PV.
Can we change specification later?
Some changes possible without complete reinstall (e.g., battery brand, inverter replacement at end of life). Other choices (e.g., optimised tilt vs roof-pitch following) are baked in at install. Specification decisions for permanent elements should be made carefully at design stage.
Do you have a preferred manufacturer or product?
We're independent of any specific manufacturer. Every quote includes specification recommendations specific to the site geometry, the farm's strategic priorities, and current market pricing. We never push a specific brand without rationale.