How Many Solar Panels Do I Need?

With UK summers getting longer and homeowners becoming more eco-conscious, there’s never been a better time to install solar panels on your home.

If you’re willing to front the initial payments, solar panels can be a worthwhile investment for your property by cutting bills, boosting energy ratings, and even earning you a bit of extra money via the SEG (Smart Export Guarantee) scheme. In the UK, there are several government schemes to help you make the transition by offering incentives for going solar.

The average energy usage vs average energy generated

In the UK, the average household consumes between 1,800 kWh and 4,200 kWh of electricity per year, depending on the size of the property and the number of occupants.

The table below gives a rough estimate of the number of solar panels your property may need, depending on its size and energy usage:

In the UK, a 350 kWh Solar Panel generates an average of 265 kWh of energy annually, meaning a medium-sized home that consumes 2,700 kWh would require 10 solar panels to meet its demand.

Factors that impact how many panels you can fit

Several factors impact the number of solar panels you can install on your property, from property size to orientation and tilt. Here are some factors that can determine the size of your Solar PV system:

• Roof Size: It's a given that larger roofs can accommodate more solar panels, meaning if your property doesn't have a large roof space, you may be limited to the number of panels you can fit.
• Roof Condition: A poorly maintained roof or one with obstructions, such as chimneys, may also limit the number of panels you can install.
• Available Floor Space: Solar panels aren't limited to roof space; if you have suitable space on the ground, you may think about installing solar panels there instead of the roof.
• Shading: Although solar panels don't need direct sunlight, they do operate best with it, and nearby buildings or trees casting a shadow on your property could mean that, although you've got roof space, it might not be worth installing solar panels.

The Calculation

To calculate an estimate of the number of panels you need, there is a formula you can use. To complete this formula, there are a few things you require. You first must find out what your annual energy usage is, this can be made easy with a smart meter. You then require the solar panel production ratio; in the UK, this averages out to around 3.2Wh per day per Watt. Finally, you need to know the wattage of the solar panels you’re getting – in most domestic cases, this will be 350 Watts, but it could be 450 Watts.

Once you have all the necessary information, use the formula below to calculate the estimated number of panels you might need.

Working out how many solar panels you need for your home comes down to understanding your household’s energy usage, available roof space, and the power output of the panels you choose.

Solar panels are a smart investment for eco-conscious homeowners looking to cut energy costs, boost property value, and reduce their carbon footprint, and with support from government-backed schemes and with the help of tools like smart meters, making the switch has never been easier.