Solar panels in Scotland - worth it?

Vitor

Those figures do not look silly, but I would treat the seven-year payback as optimistic rather than impossible.

A 4.2kWp system producing around 3,500kWh a year in central Scotland is plausible for a clear, south-facing roof. Home Energy Scotland says the average Scottish solar array is about 4kWp and costs around £6,500, with typical payback around 8 to 12 years. Energy Saving Trust gives Stirling examples of roughly 12 to 15 years depending on occupancy pattern, so location does matter.

The key issue is not whether you generate 3,500kWh. It is how much of it you actually use. Electricity you use yourself is worth about the import price, currently 26.11p/kWh under the July to September 2026 Ofgem cap average. Exported electricity is worth whatever SEG/export tariff you choose, and SEG payments are not automatic. You normally need MCS certification and a smart meter.

Very roughly, if you generated 3,500kWh and used 40% directly, the panels might save/earn around £600 a year depending on export rate. That makes £6,250 look more like a 10-year payback than seven. With a battery, you may use more of your own solar, but the battery’s extra £3,750 cost has to be justified by the difference between import and export prices. If export is decent, the battery case becomes weaker unless you also use cheap overnight charging, have an EV, heat pump, or high evening demand.

On the 9 versus 14 panels point, I would not guess. Ask both firms for the roof layout, panel dimensions, fire/access margins, inverter size, expected annual generation, shading report, and whether any DNO approval/export limit is assumed. Fourteen panels may be perfectly possible, or it may be an optimistic desktop design.

My instinct: panels probably make sense on that roof; the battery needs much more scrutiny.

FFHillbilly

https://forums.moneysavingexpert.com/discussion/comment/82033584#Comment_82033584

the more wars that kick off in the meantime will reduce the payback period even more

Savvy_Sue

@Vitor said:

On the 9 versus 14 panels point, I would not guess. Ask both firms for the roof layout, panel dimensions, fire/access margins, inverter size, expected annual generation, shading report, and whether any DNO approval/export limit is assumed. Fourteen panels may be perfectly possible, or it may be an optimistic desktop design.

And I must admit that my question regarding the discrepancy in the no. of panels was "but are they the same size in each quote?"