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How many solar panels do you need? Find the ideal number for your home

Mikael Kristianslund

Solar panels on a roof
August 16, 2023

Solar energy is making waves in the UK, and for a good reason. It's sustainable, reduces carbon footprint, and can save homeowners a significant amount on energy bills.

But one question often lingers in the minds of UK homeowners: "How many solar panels do I need?" Let's figure this out once and for all, and also find the answer tailored just for you.

Why it's crucial to get the right number of panels

When considering solar panels for your home, it's not just about filling up roof space or trying to generate as much power as possible. It's about finding the sweet spot that aligns with your energy needs and financial considerations.

Too few, and you might not generate enough power for your needs. Too many, and you could be overspending without reaping additional benefits. Moreover, while selling excess energy back to the grid sounds appealing, the returns might not always justify the extra cost. It's essential to strike a balance, ensuring you harness solar energy effectively while getting the best value for your investment.

A basic guideline for how many panels you need

The primary driving factors in determining solar panel needs are the size of the home and the number of residents. Larger homes and more occupants typically mean higher energy consumption.

Beyond these, secondary factors come into play, including the type of home, efficiency of household appliances, home insulation quality, and local climate. The average three-bedroom home in the UK will typically require about 10 solar panels.

Here is a general guideline for how many panels you need based on number of bedrooms in your home.

Solar panel requirements by house size
House size Solar panels needed Roof space needed Average annual output
1-2 bed 6 12 m² 3,600 kWh
3 bed 10 20 m² 6,000 kWh
4-5 bed 14 28 m² 8,400 kWh

This table provides a general guideline, but individual energy needs can vary. It's always best to consult with a solar expert for a tailored assessment.

Step-by-step guide to calculating your solar panel needs

Review your annual electricity usage

Begin by taking a close look at your energy bills from the past year. This exercise will offer insights into your annual electricity consumption. If you're uncertain, your energy supplier can furnish this data. To put things into perspective, a typical three-bedroom house in the UK consumes about 2900 kWh annually.

Consider future energy upgrades

Planning on making other energy-efficient changes to your home? Remember, if you switch to a heat pump, you'll cut down on gas consumption, but your electricity demand will surge. Conversely, adding insulation can reduce your energy needs. If you're thinking of a full home retrofit, estimating the exact number of solar panels becomes trickier. Get a free energy audit of your home to get the exact numbers.

Divide by solar panel output

In the UK, a conventional 400W solar panel yields roughly 600 kWh each year. Different panels have different output, but it's usually in the 300W-500W range. By dividing your yearly electricity consumption by this amount, you can approximate the number of panels required.

Assess your roof space

Every solar panel occupies around two square metres. It's crucial to ensure your roof has enough space for the panels you have in mind. Also, take into account the orientation of your roof and potential shading, as these factors can influence panel efficiency.

Beyond the roof: Other considerations

The direction and angle of your roof

In the UK, south-facing roofs are ideal for solar panels as they receive the most sunlight. However, east and west-facing roofs can also be suitable. The angle of your roof can also influence how much sunlight your panels receive, with 30-40 degrees being optimal in the UK.

Local climate and sunlight hours

The UK might not be famous for its sunny weather, but many regions receive ample sunlight for solar panels to be effective. However, it's worth noting that panels in sunnier areas will generally produce more electricity.

Potential future energy needs

Are you planning to buy an electric car or add an extension to your home? Anticipating future energy needs can influence the number of panels you should consider now.

Solar panel output

In the UK, a conventional 350W solar panel yields roughly 265 kWh each year. Different panels have different output, but it's usually in the 300W-500W range. By dividing your yearly electricity consumption by this amount, you can approximate the number of panels required.

Solar panel lifespan

Solar panels aren't just a short-term investment. Most panels come with a warranty of 25 years, but they can often last much longer. Over time, however, the efficiency of a solar panel can decrease. On average, solar panels lose about 0.5% of their efficiency each year. This degradation rate means that after 25 years, a panel will operate at about 87.5% of its original capacity. When calculating the number of panels you need, consider how much energy you'll require in the future, not just today.

Taking the next step with solar

With this guide in hand, you're all set to figure out the right number of solar panels for your home.

You can now confidently chat with a solar expert. Just share details about your home's electricity use and the size of your roof, and you'll get clear advice on the panels you need.

Ready to dive deeper? Try out our energy upgrade tool to find out if solar is right for your home. We also help you get quotes tailored for your home from our trusted partners. Your solar journey is just around the corner!

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