The comparison in 2026
When adding battery storage to a UK farm solar PV system, you face a topology choice — DC-coupled (battery shares the PV inverter) or AC-coupled (battery has its own inverter). Each has tradeoffs.
Detailed comparison
DC-coupled architecture. Battery connects on the DC side, before AC conversion. Shares the PV inverter (typically a hybrid inverter capable of both PV and battery management). Round-trip efficiency: approximately 92-95% (single conversion path). Cost: typically £400-£600 per kWh installed. Best for: new installations being designed from day one. AC-coupled architecture. Battery has its own inverter; connects to the existing AC system. PV inverter and battery inverter operate independently. Round-trip efficiency: approximately 88-92% (two conversion paths). Cost: typically £450-£700 per kWh installed (slightly higher due to two inverter systems). Best for: retrofit additions to existing PV installations. For new installations. DC-coupled wins. Better efficiency, lower cost, more elegant system design. Most major hybrid inverter brands (SolarEdge, Goodwe, Sungrow, Fronius) support DC-coupled topology. For retrofit additions. AC-coupled wins. Doesn't require modifying the existing PV inverter setup. Can be added to any existing PV system without major rewiring. Standard battery brands all support AC-coupled retrofit. When to use each. DC-coupled: any new install combining PV + battery from day one. AC-coupled: any retrofit addition to existing PV system; situations where the battery is being installed independent of the PV install. Inverter compatibility. DC-coupled requires a hybrid inverter (SolarEdge Energy Hub, Goodwe ET series, Sungrow SH series, Fronius Symo Hybrid, GoodWe EH series). AC-coupled works with any string inverter (battery has its own inverter). Recommendation. For new installations combining PV and battery from day one: DC-coupled. For retrofit additions: AC-coupled. We design both topologies regularly and recommend based on the project context.
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. We model multiple specification scenarios in every feasibility study where the choice is material. Send us your half-hourly meter data and building dimensions — we deliver a free desk feasibility within 7 working days, 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; we model alternative scenarios 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.