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What Size Solar Panel System Do I Need for My Scottish Home?

Solar price analysis by the Solar Installers Scotland team | Updated March 2026

Quick Answer

The typical Scottish home needs a 4-4.5kWp system (10-12 panels). This costs £6,000-£7,500 installed, generates 3,200-4,050 kWh per year, and saves £550-£750 annually on electricity bills. Your ideal size depends on three things: electricity usage, roof space, and whether you have or plan to add an EV or heat pump.

System Size Guide by Home Type

Use this table to find your starting point. Generation figures are for south-facing roofs in central Scotland (950 kWh/m²/year irradiance).

Home TypeAnnual UsageRecommended SizePanels NeededAnnual GenerationEstimated Cost
1-2 person flat1,500 - 2,500 kWh2 - 3 kWp5 - 81,600 - 2,700 kWh£3,500 - £5,000
3-bed house3,000 - 4,500 kWh4 - 4.5 kWp10 - 123,200 - 4,050 kWh£6,000 - £7,500
4-5 bed house5,000 - 7,000 kWh5 - 6 kWp13 - 164,000 - 5,400 kWh£7,500 - £10,000
+ EV owner (add to above)+3,000 - 4,500 kWhAdd 2 - 3 kWp+5 - 8+1,600 - 2,700 kWh+£3,000 - £4,500
Heat pump home+3,000 - 5,000 kWh5 - 6 kWp minimum13 - 164,000 - 5,400 kWh£7,500 - £10,000

Panel count assumes 400W panels. Costs include installation, inverter, and 0% VAT. Generation figures are annual estimates for south-facing orientation in central Scotland.

How to Find Your Actual Electricity Usage

1

Check your smart meter

If you have a smart meter, your in-home display shows daily, weekly, and monthly usage. Multiply your daily average by 365 for annual consumption. Most accurate method.

2

Check your energy bills

Your annual statement shows total kWh consumed. Check 12 months of bills and add up the kWh figures. Available in your supplier's online account or app.

3

Use the table above

If you cannot find exact figures, use our home type estimates as a starting point. Your installer will refine the recommendation during the site survey based on your specific usage patterns.

Roof Space: How Many Panels Actually Fit?

A standard 400W panel measures approximately 1.7m x 1.1m (1.87m²). Here is how typical Scottish roof types translate to panel capacity:

Roof TypeUsable Area (South-Facing)Panels That FitSystem Size
Mid-terrace (2-bed)10 - 14 m²5 - 72 - 2.8 kWp
Semi-detached (3-bed)15 - 20 m²8 - 103.2 - 4 kWp
Detached (3-4 bed)20 - 30 m²10 - 164 - 6.4 kWp
Large detached (4-5 bed)30 - 45 m²16 - 246.4 - 9.6 kWp
Bungalow25 - 40 m²13 - 215.2 - 8.4 kWp

Factors that reduce usable roof space

  • •Dormer windows (lose 2-4 panel spaces)
  • •Velux/roof lights (lose 1-2 panel spaces each)
  • •Chimney stacks and shading from them
  • •Soil vent pipes and aerials
  • •Required edge setbacks (minimum 300mm)
  • •Trees or buildings causing shading

South vs East/West Orientation Impact

South-Facing (Optimal)

  • •100% of potential generation — this is the benchmark
  • •Peak generation around solar noon
  • •4kWp generates approximately 3,400 kWh/year in Scotland
  • •Best for homes with high daytime usage
  • •Optimal roof pitch: 35-40 degrees

East/West Split

  • •80-85% of south-facing generation
  • •Generation spread across morning and evening
  • •4kWp generates approximately 2,700-2,900 kWh/year
  • •Better self-consumption if home morning and evening
  • •Can fit more panels total (both roof slopes)

Key insight: An east/west roof is not a reason to avoid solar. While each panel generates 15-20% less, you often have double the available roof space. A 5kWp east/west system can easily outperform a 3.5kWp south-facing system in total annual generation. Your installer should model both options to find the best approach for your roof.

Battery Sizing Guide

A battery stores excess daytime solar generation for use in the evening. Choosing the right size maximises savings without overspending on capacity you will not use.

Solar System SizeRecommended BatteryExample ProductsAdditional Annual SavingsBattery Cost
2-3 kWp3.2 - 5 kWhGivEnergy 5.2, Tesla Powerwall (shared)£150 - £250/year£2,500 - £3,500
4-4.5 kWp5.2 - 6 kWhGivEnergy 5.2, Fox ESS£250 - £400/year£3,000 - £4,500
5-6 kWp8 - 10 kWhGivEnergy 9.5, Tesla Powerwall 2£350 - £500/year£4,500 - £6,500
6+ kWp (with EV/heat pump)10 - 13 kWhGivEnergy All-in-One, Tesla Powerwall 2£450 - £650/year£5,500 - £8,000

Battery savings assume shifting excess solar generation from SEG export (4.1p/kWh) to evening self-consumption (24.5p/kWh). Actual savings depend on your usage patterns and tariff.

Get a Personalised Size Recommendation

Every home is different. Get a free site survey from MCS-certified installers who will model your specific roof, usage, and recommend the optimal system size for your Scottish home.

Get Free Size Recommendations

Frequently Asked Questions

A typical 3-bedroom house in Scotland uses 3,000-4,500 kWh of electricity per year. A 4-4.5kWp solar system (10-12 panels) is the ideal size, generating 3,200-4,050 kWh annually. This covers 70-90% of your electricity needs and delivers the best return on investment.
A standard 400W solar panel measures roughly 1.7m x 1.1m (1.87m2). Most Scottish 3-bed semi-detached homes have 15-20m2 of usable south-facing roof space, fitting 8-10 panels (3.2-4kWp). Detached homes often have 25-35m2, fitting 13-18 panels (5.2-7.2kWp). Dormers, velux windows, and chimneys reduce usable space.
Not necessarily. The optimal system size matches your electricity usage. Oversizing means you export more electricity at low SEG rates (4-5p/kWh) instead of offsetting grid electricity at 24.5p/kWh. However, if you plan to add a battery, heat pump, or EV charger in future, sizing up makes sense.
Yes. An EV typically adds 3,000-4,500 kWh to your annual electricity usage. We recommend adding 2-3kWp to your base system size. A 3-bed home with an EV should target 6-7kWp (15-18 panels) to cover both home and vehicle charging.
For a typical 4kWp system in Scotland, a 5.2-6kWh battery captures most excess daytime generation. Larger 4-5 bed homes with 5-6kWp systems benefit from 8-10kWh batteries. For homes with EVs or heat pumps, 10-13kWh batteries maximise self-consumption and deliver the best savings.
Yes, significantly. An east/west split roof generates roughly 15-20% less than south-facing in Scotland. To match the output of a 4kWp south-facing system, you would need approximately 4.8-5kWp on an east/west roof. Your installer should model your specific roof to recommend the right size.