Category - Solar
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Will Scholfield, Engineer

5 Sep : Updated 10 Apr ● 6 min read

How many solar panels do you need for your home?

When switching to renewable sources of energy, you won’t want to misjudge or overestimate the installation (otherwise, it wouldn’t be very efficient). So you’ll need to ask yourself “how many solar panels do I need?”, before making the investment. 

Luckily, the team at BOXT have put together an extensive guide to how many solar panels are typically needed for the average UK household. 

We’ll break down variable factors such as different sizes, how much energy each panel generates, how to calculate what you’ll need and whether it is possible to take yourself completely off-grid using solar panels.

What different sizes of solar panels are available?

A solar panel's size is usually measured in watts (W) or kilowatts (kW), which correspond to the panel's power output. Below are some typical solar panel sizes:

  • Small-scale panels: Usually measuring 1 metre by 1.6 metres, these panels have power outputs between 100 and 350 watts. They are appropriate for small-scale domestic uses such as supplemental grid power, battery charging, and powering a single appliance.
  • Standard residential panels: These panels typically have a power output of between 250 and 425 watts and range in size from 60 to 72 cells. They are appropriate for smaller installations and rooftops in private residences.
  • Commercial panels: These panels are intended for commercial or industrial applications and are larger than residential panels. They frequently feature 72 to 96 cells and have a 400 to 600 watt output per panel.
  • Utility-scale panels: Finally, as the name suggests, utility-scale panels offer a much higher power output and are employed in large-scale solar power plants. They can range in size from 72 to 144 cells or more, and each panel can generate up to 500 watts of power.

The number of people living in a household is one of the determining variables in calculating what size solar panel you’ll need. 

For example, an average household of 2-3 people uses roughly 2,900 kWh of power annually, therefore, standard residential solar panels would be ideal. However, if you’re a van dweller then you may want to consider installing small-scale solar panels, as your demand for energy will be considerably less.

How much energy can a typical solar panel generate each year?

The typical solar panel generates between 170 and 350 watts per hour, depending on the location and the weather. This equates to approximately 0.17 to 0.35 kWh per solar panel.

This means that a 4 kW solar power system on an average-sized home can generate up to 3,000 kWh of electricity each year, which also accounts for the number of hours of sunlight.

However, a solar panel's annual energy output is determined by a number of variables, including the panel's size, efficiency, position, orientation, shading, and local weather conditions.

Roughly, each different sized panel can produce up to: 

Solar Panel SizeEnergy Output (Measured in Watts)
Small-scale panels100 and 350 watts
Standard residential panels250 and 425 watts
Commercial panels400 to 600 watts
Utility-scale panelsup to 500 watts

How many solar panels do you need?

When choosing solar energy for your home, you will need to take into account the aforementioned factors such as; the size of your home, the amount of people living in the property, the amount of energy you consume, and of course, your budget. 

It can cost anywhere between £3,000 - £18,000, or above, to install solar panels. Check out: Solar panel prices: An updated guide for 2023 for more information on unit and solar installation costs. 

Typically, a 4kW solar panel system is one of the most popular sizes for a household in the UK. The 4kW solar panel system covers about 29 square metres of your roof, costs between £6,000 and £7,000, and requires about 16 panels.

Roughly, follow this guide when deciding how many solar panels you need for your solar system.  

Solar System WattageNo. of PeopleNo. of Solar Panels Needed
3kW system28 panels
4kW system310 panels
5kW system412 panels
6kW system5+14 panels

If you are ready to make the switch, it is strongly advised you get a few installation quotes before committing. With BOXT, our solar panel service is unrivalled, with benefits such as:

  • Only 25% upfront payment
  • 15 year product warranty on all our solar panels
  • Prices starting from as little as £6,597

Simply enter your postcode to get started. 

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How to calculate the number of solar panels your home needs

  1. Find your home’s annual electricity usage: A household’s energy consumption can be determined by its energy bills. With this information, you’ll be able to understand how much energy your solar panels will need to generate daily. For instance, your daily energy use amounts to 4 kWh if your monthly consumption for a typical 30 day month is 120 kWh. This implies that the solar system should produce 4 kWh everyday on average. 
  2. Decide on the solar panels you’re going to use: As aforementioned, standard residential panels (4kW unit) are the most popular in the UK. However, if you are looking for a larger or smaller unit then there are options available. 
  3. Establish how much suitable installation space you have available: One of the most important variables to consider, alongside budget, is how much space you have to install solar panels. 

Among this, you’ll need to take into account the different variables that will affect your solar panels efficiency, and whether they are worth the investment

Note that separate regions in the UK have different sun hours per day: With on average, England having 4.1, Scotland has 3.7, Northern Ireland 3.2 and Wales 3.3.

Can you go completely off-grid using solar panels?

While going off-grid with solar panels is a possibility and can give you energy independence, it also requires  careful planning, routine system maintenance, and consideration of your energy consumption patterns to guarantee a reliable power source.

Things you’ll need to consider before going off-grid: 

  • Space: Do you have adequate space to install and store all the equipment that makes energy independence possible? These include batteries, solar panels, an inverter, water tank(s) and, in some cases, a backup generator.  
  • Affordability: Installing solar panels and relying on renewable energy can be a huge investment, so it’s best to understand whether it is right for you and your needs before taking the financial leap.
  • Longevity: If you’re planning to stay in your home for a number of years then going off-grid might be a good idea, however, if you plan to move it could make the home harder to sell on the housing market.


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