You’re interested in making your home more eco-friendly?
You’re interested in making your home more eco-friendly by adding some solar panels. However, before you even start looking at the different systems and options, there’s one massive question on your mind: how many solar panels do I need for my house?
We’d love to give you a simple answer, but the truth is it depends on each household. Some houses can get away with as little as five solar panels in their system, while others will need more than ten.
Why does this matter? Because choosing the wrong amount of solar panels can cause a host of problems. Pick too few, and you can’t generate enough solar energy to power your home. Pick too many, and you’re spending more money than necessary – choosing the right amount will save time and ensure your solar system handles your regular electricity demands.
We appreciate this already seems complex and frustrating, which is why we’ve written this guide! We’ll explain everything you need to know about how many solar panels you need to power your home. By the end, you’ll be able to pick the perfect amount with confidence.
How Many Solar Panels Do I Need? Factors Influencing Your Requirements
Determining the ideal number of solar panels depends on a few critical factors. Let’s assume that your home is already suitable for solar panel installation, which means there’s enough room on the roof and it gets the minimal amount of sunlight required for the panels to be worth it.
From here, you’ll look at the number of solar panels based on the following:
- Your average electricity usage
- How efficient your chosen solar panels are
- The physical size of your home
- Your roof’s sun exposure
As a quick example, a small two-bedroom home that only uses 2,700kWh of electricity per year will need fewer solar panels than a four-bedroom house that uses over 5,000kWh per year. Based on the electricity usage alone, the bigger house may need twice as many solar panels to meet their demands.
Of course, the other factors also affect your decision, so let’s discuss them in more depth to help you understand their impact.
Calculating Your Home’s Solar Energy Needs
First of all, you must consider how much solar energy is required to power your home throughout the year. There’s an easy way to do this: check your electricity bills to see your average annual electricity usage.
For context, Ofgem estimates the typical UK household will use 2,700kWh of electricity each year.
With that in mind, if you want a solar panel system to provide 100% of your home’s electricity, then you’d need one that’s capable of producing this amount of energy during the year. There’s actually a very simple calculation to help you work out how many solar panels you need in terms of energy usage:
Your annual electricity usage (kWh) / The solar panel’s yearly electricity output (kWh)
We’ll talk about solar panel output in just a moment, though The Eco Experts suggest the average 350W panel can produce 265kWh of electricity per year. Fit that into our calculation with the average household’s electricity usage, and you get this:
2,700 / 265 = 10.12
Round that down, and it means you’d need around 10 350W solar panels to meet your home’s energy needs.
As we’ve already touched upon, you can still influence this figure by taking the other factors into account – starting with an obvious one: the solar panel wattage and efficiency.
Understanding Solar Panel Wattage and Efficiency
Solar panel wattage describes the maximum amount of electricity the panel can produce. The higher the wattage, the more power the panel will be able to produce. In the UK, you’re normally looking at panels between 300 – 450 Watts. You then multiply the watts per panel to get the total power output of your solar system.
For example, we install a range of solar systems, including a 3.4kW system comprising eight 440W solar panels. Increase this to twelve 440W solar panels, and it becomes a 5.1kW solar system.
In theory, you’d need fewer solar panels if you opted for ones with a larger wattage because they can produce more power. However, wattage is not the same as efficiency. Solar panel efficiency refers to how good the panels are at converting solar energy into electricity. More efficient panels are capable of a better overall power output per metre squared. Therefore, you could have panels of the same wattage, but you’d need fewer of the ones with better efficiency.
This is something to keep in mind if you’re struggling for space on your roof. Look for the most efficient panels to get your desired power output without needing to cover your entire roof in solar panels.
Assessing The Size Of Your Home
Speaking of which, the size of your home will play a very crucial role in answering the question, how many solar panels do I need?
In many ways, this is almost the most critical factor of all because it provides a limit. Small homes with small roofs may be restricted to only 5 or 6 solar panels. There’s nothing you can do about that – your home simply can’t handle more. To give you some context, the average solar panel is about 2 metres squared.
Also, keep in mind that the size of your home will normally dictate your energy output. Larger homes with more people and appliances will produce more electricity, which means they need a more powerful solar system.
Analysing Your Annual Sun Exposure
Finally, you have to think about how much sun your roof gets throughout the year. This also determines your solar system’s annual energy output. If you don’t get much sun, then the panels can’t convert much solar energy. Therefore, you’re unlikely to produce as many yearly kWh as a solar system with better sun exposure.
What influences sun exposure?
- The way your roof is facing: North-facing roofs get less sunlight than south-facing ones. East and west-facing get somewhere in between, but south-facing roofs are the most optimal for solar panels.
- Shade: According to MoneySavingExpert, the peak period for daylight is between 10am and 4pm. Ideally, you want your roof to be unshaded during these hours.
- The pitch of your roof: The way your roof is angled also comes into play. Roofs with a 30-40-degree angle are judged to be the best for sun exposure in the UK.
To give you a rough idea of how much sunlight to expect, the average UK home gets 4-5 hours of sunlight per day. This decreases to 3.7 hours for homes in Scotland.
Estimating How Many Solar Panels You Need To Power Your Home
Gathering all the factors above, we can now run an estimate for how many solar panels you need to power your home. To do this, we’ll have to run a couple of calculations – starting with the Annual Output for a solar panel in kWh.
The calculation looks like this:
Solar Panel Power (kW) x Average Sunlight Hours Per Year
Find the solar panel power by taking its wattage and dividing it by 1,000. Find the average sunlight hours by taking the daily average and multiplying it by 365.
Let’s imagine you’re looking at a 440W solar panel, and you get around 3.5 hours of sunlight per day:
0.44kW x 1277.5 = 562.1kWh
Then, you can go back to the original calculation to find how many of the 440W solar panels you need for your home:
Your annual electricity usage (kWh) / The solar panel’s yearly electricity output (kWh)
Again, we’ll use the 2,700kWh average here, which would mean the calculation looks like this:
2,700 / 562.1 = 4.80
You can’t have .80 of a solar panel, so we’d round that up to five 440W solar panels. Please bear in mind that these are estimations, and 440W panels are larger than ones with a smaller wattage.
Use Online Calculators For More Solar Panel Assistance
Instead of doing the calculations yourself, you can use different online calculators to estimate how many solar panels you need – and the right system for your home. We actually have a very useful tool on our home page that helps you estimate the cost of your solar panels, as well as how many will fit on your roof. Click here to give it a go.
All you need to do is type in your address and then use our interactive map to outline your roof. Provide some basic energy usage details, and we’ll give you a suggestion for the ideal solar system.
Ready To Go Solar? Contact Us For A Customised Quote
This guide should give you a good idea of how many solar panels you need to power your home. Get in touch with us today if you’re ready to take the next steps. You’ll get a completely free customised quote to start your journey towards better energy efficiency and lower electricity bills!
