SP Energy Networks G99: Timing & Tips
How the G99 process works for commercial solar in SP Energy Networks territory — typical timelines and how to avoid delays.
Quick answer
How quickly solar pays back in Scotland depends on how much of the power you use at home, your tariff and your roof. Modern panels work efficiently in Scottish daylight (you don't need direct sun), and 0% VAT until 31 March 2027 and Smart Export Guarantee export payments both help.
What this article covers
This guide explains the cost, payback, funding routes and practical install considerations for g99 applications in Scotland — pulled from our experience of MCS-certified installations across Scotland's Central Belt.
Costs in Scotland
- 4kWp solar install: £6,500-£8,500
- 4kWp solar + 5kWh battery: £10,500-£13,500
- 8kWp solar + 10kWh battery: £15,000-£19,000
- ASHP (12kW): £12,000-£18,000 (often £0-£3,000 after HES grant + loan)
Payback maths
A typical 4kWp install in the Central Belt generates around 3,600 kWh a year. If half of that is used at home at the Ofgem price cap (26.11p/kWh in South Scotland, October to December 2026) and the rest is exported at 12p (Octopus Outgoing), it is worth about £686 in the first year, so a £7,500 system pays back in around 11 years at current prices, before panel degradation, price changes and maintenance. Using more of the power yourself, for example with a battery, shortens that; we work out your own figures at survey.
Funding and finance routes
- 0% VAT: qualifying domestic installations are zero-rated until 31 March 2027
- Smart Export Guarantee (SEG): your supplier pays you for every unit you export
- HES heat pump, biomass or heat network: up to £7,500 grant plus up to £7,500 interest-free loan, with a £1,500 grant uplift in eligible rural and island areas
- HES insulation: solid wall £7,500 grant / £2,500 loan; loft, cavity and underfloor £1,500 grant / £500 loan
- Lender finance via Ideal4Finance (FRN 703401) — commercial credit from a lender, not a government scheme
Choosing a Scotland installer
Look for: MCS certification (mandatory for SEG registration and for any HES-funded heat measure), TrustMark registration, RECC code compliance, in-house engineers (not subcontractors), insurance-backed warranties via HIES, and clear written quotes with no scope creep.
Next step
Get a free no-pressure quote from Ecoaim — survey + fixed-price quote within 24 hours. Call 03330 384 380 or use our online form.
Call 03330 384 380 or get a quote online — survey + quote within 24 hours.