Swansea’s domestic solar market is maturing. Many systems installed between 2012 and 2018 were fitted without battery storage because the technology was expensive and the case marginal. By 2026 that calculation has reversed: lithium iron phosphate battery costs have fallen roughly 60% over the same period, while the export tariff under the Smart Export Guarantee — typically 12p to 15p/kWh — remains far below the import rate of 27p to 30p/kWh. Every kilowatt-hour exported to grid rather than stored for later self-consumption leaves 12p to 15p of value on the table.
Why Swansea demand profiles suit battery storage
A standard Swansea household without occupants during the day generates solar in the hours when demand is lowest. The 950 kWh/kWp annual yield at SA1 to SA5 produces most of its daily output between 09:00 and 16:00. Without storage a significant fraction of that generation is exported at the SEG rate. With a 5 kWh to 10 kWh battery, the surplus midday generation is stored and discharged during the evening demand peak when grid import would otherwise be most costly.
At 28p/kWh import and 13p/kWh SEG export, the value difference per stored kilowatt-hour is 15p. A battery charged and discharged once daily accumulates 365 cycles per year. At 80% round-trip efficiency, a 10 kWh battery delivering 8 kWh of net daily discharge generates approximately £438 of value annually above what the same generation would earn exported.
System sizing for SA postcodes
The Victorian terraces at St Thomas (SA1), Hafod and Plasmarl typically carry 3 kWp to 4 kWp solar arrays. Semi-detached and detached stock at Sketty (SA2) and Uplands suits 4 kWp to 6 kWp. A battery sized at roughly 1 kWh to 1.5 kWh per installed kWp matches typical demand profiles without over-specifying.
| Array size | Battery | Approx. installed cost | Est. annual battery value |
|---|---|---|---|
| 3 kWp | 5 kWh | £4,200 | £180—£220 |
| 4 kWp | 7.5 kWh | £5,800 | £250—£310 |
| 5 kWp | 10 kWh | £7,400 | £330—£400 |
| 6 kWp | 10—15 kWh | £7,400—£9,600 | £380—£480 |
EV integration
Swansea Council’s zero-carbon homes programme requires EV charging provision in all new residential developments. For homeowners pairing solar with an EV, adding a solar-divert charger directs surplus generation to vehicle charging before exporting to grid — avoiding 28p/kWh import cost on every charge session. A household charging an EV four times per week at 10 kWh per session, with 55% of charge energy from solar surplus, avoids approximately £580 per year against grid charging. Combined with standard battery benefit, a 5 kWp array with 10 kWh battery and solar-divert EV charger produces total year-one benefit in the range of £1,100 to £1,300.
Retrofit versus new installation
Adding a battery to an existing Swansea solar installation typically costs less than installing battery and solar together because mounting, cabling and DNO notification work is already in place. Incremental battery-only cost for a compatible system: approximately £3,800 to £5,500 for 5 kWh to 10 kWh. Payback on the battery-only investment runs at 14 to 18 years — commercially acceptable for a 25-year asset, but less compelling than the combined solar-plus-battery payback of 7 to 9 years for a complete new install.
SolarEdge systems installed after 2019 typically accept battery integration via the StorEdge module. Older string inverter systems may require a hybrid inverter replacement. FLD assesses inverter compatibility at survey stage before quoting any Swansea battery retrofit.
Getting a battery storage survey
FLD installs battery storage across all SA postcodes, including retrofit additions to existing solar not originally installed by FLD. Call Paul on 01792 680611 or use the contact page.
