How Many Solar Panels for a 3 Bed House?

For homeowners living in a 3-bedroom home and thinking about solar panels, you’ll be wondering just how many you need.

Getting the number of solar panels right for your 3 bed property, or more specifically getting the solar capacity matched up to your energy usage, is one of the most important considerations when installing solar panels. This is because it has a direct impact on your costs, efficiency and return on investment. 

This guide aims to give you all the information you need when it comes to adding solar panels to a 3 bed house. 

How much energy does your home use?

This is probably the most important question you need to ask before you can determine the number of solar panels for your 3-bedroom home. 

On average, a medium-sized 3-bed house in the UK consumes approximately 2,700 kWh of electricity annually, according to energy regulator Ofgem. However, it’s important to note that this figure is far from universal – your actual usage, which could be above or below this average, is impacted by a variety of factors including:

• Family size and composition – A 3 bed house could be home to a number of different compositions. For example, just two adults will use much less energy than one with two adults and two teenagers. 
• Daily routines and lifestyle habits – Do you work from home? Are you out most weekdays? These patterns significantly impact energy use and the prices of electricity you have access to. 
• Energy efficiency of household appliances – Modern, energy-efficient appliances can dramatically reduce electricity consumption. For example, the average dishwasher uses between 1.2kWh and 1.5kWh per load. However an energy efficient dishwasher can use less than half of this energy. Things like hot tubs and electric vehicle chargers will significantly increase energy use.
• Insulation quality and overall home energy efficiency – Well-insulated homes require less energy for heating and cooling.
• Heating – Homes with electric heating like heat pumps will naturally use more electricity than those with gas central heating.

That’s why examining your own electricity bills is invaluable when planning a solar installation. Look for your annual consumption figure, usually provided on your bill or available from your energy supplier.

Why annual electricity use is the best measure

Whilst the 2,700 kWh average provides a useful starting point, your home’s specific energy could differ quite substantially based on the factors above. For this reason, nothing beats the accuracy of your own annual electricity consumption data when it comes to sizing your solar panel system. 

Your bills are much more precise, better reflecting your unique energy habits. This personalised data captures all the nuances of your lifestyle and home setup that general averages might miss. 

A full year’s data accounts for both winter peaks and summer drop-offs in energy use. In the UK, energy consumption varies dramatically between seasons due to heating needs and daylight hours. This gives you your own unique average across the year which helps with accurate solar system sizing. 

Examining a year’s worth of data can reveal gradual changes in your energy needs. Perhaps you’ve recently had a child, started working from home, or invested in energy-efficient appliances – all these changes will be reflected in your annual consumption.

To access this information, review your past 12 months of electricity bills or annual statement. If you can’t find this, just contact your energy provider. Many suppliers now offer online accounts where you can easily access and download your historical usage data. 

Calculating solar panels needed for a 3 bed house

To make things a little clearer, here’s an example to show how many panels a typical 3-bed house might require. 

1. Annual energy consumption: 2,700kWh
2. Daily energy need: 2,700 kWh ÷ 365 days = 7.4kWh per day
3. Account for UK solar conditions and panel efficiency: Using an average production ratio of 3.225Wh per day per Watt of panel capacity and a panel efficiency of 85%, multiply these together to get daily production in watt hours. 3.225Wh x 0.85 = 2.74Wh.  
4. Calculate system size: 7.4 kWh / 2.74 = 2.7kW system size
5. Determine panel quantity: 2,700W ÷ 370W = 7.29 panels, rounded up to 8. 

In this example, we’d round the system size up to 3kW or 3.5kW to give you a little more leeway and account for some future proofing. This means you’d need 8-10 solar panels to cover your energy needs.

This process can be updated for your specific energy usage. Just replace the 2,700kWh in step 1 with your annual consumption data and go through the process. You can also update the panel efficiency number and panel capacity in step 5.

Solar panel example setups for a 3 bed house

For most 3-bedroom properties, a system size between 3-4kW is often suitable. Here’s what that might look like:

• Using 350W panels: 9-12 panels
• Using 400W panels: 8-10 panels

For these configurations, you’re looking at taking up a roof area of between 14 and 24 square metres. This is based on a typical solar panel being around 1.7 to 2 square metres in dimension. 

It’s important to note that these are general guidelines. Your optimal setup might differ based on your specific energy needs, roof characteristics and local conditions. For example:

• A 3-bed house with high energy efficiency and south-facing roof might manage with a 3kW system (about 9 x 350W panels).
• A similar house with electric heating or an electric vehicle (EV) might need a 4kW system or even larger to account for higher energy needs. This would require 12 or more 350W panels.
• Homes with less ideal roof orientations might need more panels to achieve the same energy output.

The impact of home electrification

As the UK moves towards a greener future based on renewable energy over fossil fuels, households are becoming fully electric. Although much better for the environment, when electricity is generated from renewable sources like solar panels, this shift can have a significant impact on your home’s electricity consumption. In turn, this affects the size of the solar system you might need. 

Heating is a major area that will need to be electrified if the UK is to meet its 2050 net zero targets. Heat pumps are the solution being put forward here to replace gas-powered boilers. They run on electricity and can add a further 4,000-5,000kWh to your annual consumption. They can be used to heat water too but you will need a separate hot water storage cylinder. 

Electric boilers are another alternative. Although they aren’t as efficient as heat pumps, they can add significant energy usages to bill. 

Another area that can add to your yearly electricity use is an EV charger. Regular EV charging can add 2,000-4,000kWh a year to your totals.

A system that meets your current needs might fall short if you later add an EV or switch to electric heating. Just a few changes can potentially double or triple your electricity use. If you have firm plans, factoring these possibilities in now when sizing up your solar system can save you from needing costly system upgrades in the future.

Other factors affecting solar panel requirements

As well as future electric plans, there are several other factors that may influence the number of panels your 3-bed house might need:

• Panel efficiency – Higher-efficiency panels generate more power per square metre, potentially reducing the number required. For example, a 400W panel will produce more energy than a 350W panel of the same size.
• Roof characteristics – The direction your roof faces and its pitch affect solar exposure. South-facing roofs at a 30-40 degree angle are ideal in the UK, receiving the most direct sunlight throughout the day. However, east and west-facing roofs can still be suitable, though they might require more panels to achieve the same output.
• Geographic location – Solar irradiance levels vary across the UK. Southern England generally receives more sunlight than Scotland, Wales and Northern Ireland. Homes in sunnier regions might need fewer panels to produce the same amount of energy.
• Shading – Trees, nearby buildings or architectural features that cast shadows on your roof can impact panel performance. Even partial shading on one panel can significantly reduce the output of the entire system. Your panels will still work, just not as efficiently.

How much do solar panels for 3 bed homes cost?

Installing solar panels on a 3-bedroom home costs between £5,000 and £8,000. This is based on a 3-4kW system. This investment can lead to significant financial benefits over time. Homeowners can expect to save £400-£600 annually on electricity bills, with savings likely to increase as energy prices rise. Most systems pay for themselves within 7-12 years, and over their 25-year lifespan, total savings could reach £10,000-£15,000 or more.

Beyond direct energy savings, solar panels may increase property value and provide energy independence, protecting against price fluctuations. Maintenance costs with solar panels are pretty much zero.

Determining the ideal number of solar panels for your 3-bedroom house involves balancing current energy needs, future plans and practical considerations like roof space and budget. Whilst 9-12 solar panels suit many 3-bed homes, your optimal setup may differ based on your unique circumstances.

Ultimately, consulting with a qualified solar installer will provide the most accurate assessment for your specific situation. They can evaluate your roof, analyse your energy needs and recommend a system that offers the best balance of cost, performance and future-proofing.