How Many Solar Panels Do I Need? Complete UK Guide

One of the most common questions we receive is "how many solar panels do I actually need?" The answer depends on three factors: your electricity consumption, your available roof space, and your budget. Here is how to work it out.

Step 1: Find Your Annual Electricity Consumption

Your annual electricity consumption in kilowatt-hours (kWh) is the starting point for sizing your solar system. You can find this on your annual energy statement from your supplier, or by checking your smart meter history.

Typical UK household consumption in 2026: a 1-bedroom flat uses 1,500 to 2,000 kWh per year, a 2-bedroom house uses 2,000 to 2,800 kWh, a 3-bedroom house uses 2,800 to 3,500 kWh, and a 4-bedroom house uses 3,500 to 5,000 kWh. Homes with an electric vehicle add 1,500 to 3,000 kWh per year, and homes with electric heating add significantly more.

Step 2: Calculate the System Size You Need

In Yorkshire, a solar panel system generates approximately 850 to 950 kWh of electricity per installed kilowatt-peak (kWp) of capacity per year. To cover most of a 3-bedroom house consuming 3,200 kWh per year, you would need approximately 3.5 to 4kW of solar capacity.

A rule of thumb for Yorkshire homes: a 3kW system suits a 1 to 2-bedroom home, a 4kW system is the most popular choice for a 3-bedroom semi or terraced house, a 5kW system suits a 4-bedroom house or a 3-bedroom with EV charging, and a 6kW or larger system suits large properties or those with multiple EVs.

Step 3: Check Your Roof Space

Modern 400W solar panels measure approximately 1.7m x 1.05m, requiring roughly 1.8 square metres each. A 10-panel 4kW system needs approximately 18 square metres of usable south-facing roof. A typical 3-bedroom semi-detached has 20 to 35 square metres of south-facing roof — comfortably accommodating 10 to 16 panels.

Obstacles to account for include chimneys, roof windows, dormer extensions, satellite dishes, and shading from trees or neighbouring buildings.

Step 4: Consider Roof Orientation

South-facing roofs are ideal. East and west-facing roofs generate approximately 15 to 20% less. North-facing roofs generate too little to be worthwhile. Many homes have east-west split roofs — a split system on both sides can work well, generating more evenly throughout the day.

Step 5: Factor in Shading

Shading is the single biggest performance variable. A tree casting a shadow on even one panel for two hours a day can reduce output significantly. We assess shading carefully during our free survey and recommend micro-inverters, power optimisers, or panel repositioning to minimise impact.

Getting the Right Answer

The definitive answer comes from a free site survey where we measure your exact roof dimensions and orientation, assess shading, review your actual energy bills, design a system specific to your property, and provide a precise generation estimate based on your actual roof.

Call 0333 577 5464 or book a survey online — we serve all of Yorkshire and the Humber.