How Many Solar Panels Do I Need?
The number of solar panels you need depends on three key factors: your annual electricity consumption, the wattage of the panels, and your available roof space. In Manchester, a typical household using 3,500 kWh per year would need a 4kW system — that is around 10 panels using modern 400W modules. But getting the sizing right is crucial: too few panels and you will not offset enough of your bill, too many and you are paying for capacity you do not need.
Manchester Renewables provides free, no-obligation system sizing based on your actual energy data. We go beyond simple calculators by factoring in your roof orientation, pitch angle, shading, and the specific solar irradiance data for the Manchester postcode area (approximately 950-1,050 kWh/m² per year). This guide gives you a solid starting point before your free home survey.
What Is Included?
Usage-Based Sizing
We analyse your annual electricity consumption (from bills or smart meter data) to determine the system size that offsets the right proportion of your usage.
Roof Space Assessment
Each 400W panel requires approximately 1.8m² of roof space. We calculate how many panels your roof can physically accommodate, accounting for setbacks and obstructions.
Orientation & Yield Modelling
Using Manchester-specific solar irradiance data, we model expected generation based on your roof's compass direction and pitch angle.
Future-Proofing Advice
Planning an electric vehicle or heat pump? We factor in future energy demand increases so your system is sized for tomorrow, not just today.
Smart Export Guarantee (SEG): 4-15p per kWh Exported
Any surplus electricity your solar panels generate is exported to the grid, earning you SEG payments. Getting the right system size is key — a well-sized system maximises self-consumption (using energy as you generate it) while still exporting enough to earn meaningful SEG income.
Why It Matters
- A correctly sized system maximises your return on investment and minimises payback period
- Oversizing wastes money upfront; undersizing means higher ongoing electricity bills
- Panel wattage has increased dramatically — modern 400-430W panels mean fewer panels for the same output
- Manchester's solar irradiance supports 850-950 kWh generation per kWp installed annually
Cost Guidance
As a rough guide: a 3kW system (8 panels) costs £4,500-£5,800, a 4kW system (10 panels) costs £5,500-£7,500, a 5kW system (12-13 panels) costs £6,500-£8,500, and a 6kW system (15 panels) costs £7,500-£9,500. All prices include 0% VAT, installation, and MCS certification. Adding a battery adds £2,500-£5,000 depending on capacity.