Solar Panels: The Complete Buying Guide

How Do Solar Panels Work?

Solar photovoltaic (PV) panels convert sunlight into electricity using semiconductor cells - typically silicon. When photons from sunlight hit the cells, they knock electrons loose, creating a flow of direct current (DC) electricity. An inverter then converts this into alternating current (AC) that powers your home.

Modern panels work even on cloudy days, although output is reduced. The UK receives enough sunlight to make solar panels a worthwhile investment across all regions, with the south and south-west performing best.

What Size System Do I Need?

System size depends on your electricity consumption, roof space, and budget. Here's a general guide:

How Much Do Solar Panels Cost?

The cost of solar panels has fallen dramatically - by over 80% since 2010. In 2025, you can expect to pay between £5,000 and £9,000 for a typical residential installation including panels, inverter, mounting, and labour.

Key factors affecting cost include system size, panel brand and efficiency, inverter type (string vs micro-inverters), scaffolding requirements, and whether you add battery storage.

Since April 2022, residential solar installations benefit from 0% VAT (reduced from 5%), saving you an additional £250-£450 on a typical system. This reduction is in place until at least March 2027.

What's the Return on Investment?

A typical 4kW system generates around 3,400-3,800 kWh per year in the UK. Assuming you use 40-50% of the electricity directly (self-consumption) and export the rest via the Smart Export Guarantee (SEG), annual savings typically range from £400 to £800.

This means a payback period of 8-12 years, after which you enjoy 15-20 years of essentially free electricity. Adding a battery increases self-consumption to 70-80%, accelerating your ROI.

Why MCS Certification Matters

MCS (Microgeneration Certification Scheme) is the quality standard for renewable energy installers in the UK. Choosing an MCS-certified installer is important because:

• Required for SEG payments - you can only receive export payments with an MCS-certified installation
• Consumer protection - MCS installers must follow strict standards and provide guarantees
• Quality assurance - regular audits ensure high installation standards

Questions to Ask Your Installer

1. Are you MCS certified? Can I see your certificate number?
2. What panel brand and model do you recommend, and why?
3. What output can I realistically expect for my roof orientation?
4. Is scaffolding included in the quote?
5. What warranties do you offer on panels, inverter, and workmanship?
6. Do you handle DNO notification and SEG registration?
7. How long will the installation take?
8. Can I add a battery later, and is the system designed for this?