Understanding the true cost of solar panels is essential for making an informed decision. In this comprehensive guide, we break down every cost component: from the panels themselves to installation, electrical work, and maintenance.
System Costs by Size
The total cost of a solar PV system includes the panels, inverter, mounting hardware, electrical components, labour, and site works. Here’s what you can expect to pay in 2026:
| System Size | Panel Cost | Inverter & Hardware | Installation Labour | Total Installed Cost | Cost per Watt |
|---|---|---|---|---|---|
| 3kW | £1,800 – £2,400 | £800 – £1,200 | £2,400 – £2,900 | £5,000 – £6,500 | £1.67 – £2.17 |
| 4kW | £2,400 – £3,200 | £900 – £1,400 | £2,700 – £3,400 | £6,000 – £8,000 | £1.50 – £2.00 |
| 5kW | £3,000 – £4,000 | £1,000 – £1,600 | £3,000 – £3,400 | £7,000 – £9,000 | £1.40 – £1.80 |
| 6kW | £3,600 – £4,800 | £1,200 – £1,800 | £3,200 – £4,400 | £8,000 – £11,000 | £1.33 – £1.83 |
Breakdown of System Costs
Solar Panels (40-50% of total cost)
Modern solar panels from established manufacturers cost £150-£300 per panel. A typical 4kW system uses 10-12 panels at around 400W each. Premium brands like SunPower (£250-£300/panel) cost more but offer superior efficiency (22%) and longevity. Budget brands like Trina or JA Solar (£150-£180/panel) offer better value with 18-20% efficiency.
Inverter (15-20% of total cost)
The inverter converts DC power from panels to AC power for your home. Options include:
- String Inverters: £800-£1,200 for 4kW, most common, cost-effective
- Microinverters: £1,200-£1,600, higher cost but better for shading, 25-year warranty
- Hybrid Inverters: £1,400-£2,000, required for battery storage
Installation Labour (30-40% of total cost)
Installation typically takes 1-2 days and costs £2,400-£4,400 depending on roof difficulty. Factors affecting labour costs:
- Roof pitch and access difficulty
- Distance from ground level to electrical points
- Roof material (tiles, slate, flat)
- New circuit installation needs
- Location (London/South East premium)
Electrical Works and Certification (5-10% of total cost)
Electrical upgrades and MCS certification typically cost £400-£800:
- Isolator switches and DC protection: £150-£250
- AC cable runs and distribution board work: £200-£400
- MCS certification and documentation: £150-£200
- DNO notification (usually included): £0-£100
Get Detailed Quotes for Your Home
Compare exact pricing from multiple installers based on your roof and requirements.
What Affects Your Solar Costs?
1. Roof Condition and Type
Slate or clay tiles cost 10-20% more to work with than standard concrete tiles. Pitched roofs are more straightforward than flat roofs. If your roof needs work before solar installation, budget an additional £1,000-£3,000.
2. Electrical Upgrades
Older homes may need consumer unit (fuse box) upgrades (£300-£600) or new circuits. Modern homes with recent electrical work rarely need upgrades.
3. Battery Storage Addition
Adding a battery system increases costs by £2,500-£6,000. Tesla Powerwall 2 (13.5 kWh) costs around £6,000 installed. GivEnergy and Growatt options are available from £2,500-£4,000.
4. Scaffolding Requirements
Most installations don’t require scaffolding. If needed (listed building, high roof, etc.), budget an additional £500-£1,500.
Financing Your Solar Installation
Cash Purchase
Buying outright offers the best long-term savings. Payback period is 6-10 years with ongoing benefits after that.
Finance/Loans
Many installers offer 0% APR finance over 5-10 years. Monthly payments for a £7,000 system over 10 years would be approximately £58/month. Check you’ll save more than the finance cost annually.
Home Improvement Loans
Secured loans typically charge 3-7% APR. Unsecured personal loans charge 5-12% depending on credit. Generally more expensive than installer finance.
Return on Investment
A typical 4kW system costing £7,000 generates approximately 3,400 kWh annually. In 2026 UK electricity rates (28p/kWh), this equals £952 in annual savings. With the payback period of 7.4 years, you’ll save money from year 8 onwards. Over 25 years, total savings exceed £17,000 (accounting for 2% annual bill increases).