How many solar panels do you need?
Solar panels have come to symbolise sustainable living in the 21st Century. Indeed, in the pursuit of greener domestic energy sources and a reduced reliance on fossil fuels, these generators of clean energy are becoming more and more affordable and accessible in the UK. However, like any change to the status quo, you have to do your due diligence if you’re looking to invest in solar panels for your own home. One of the most pertinent questions that will likely come up is - how many solar panels are required to power a house effectively?
Naturally, the answer to this question depends on various factors. This includes your typical energy consumption, location, roof space, and the efficiency of the solar panels you purchase. Indeed, with this in mind, researching solar panels can be overwhelming. To help you make the best decision for your home, this guide answers some of the most common questions those looking to invest in domestic solar energy tend to ask.
How many solar panels do you need to power a house?
The number of solar panels needed to power a house depends on a few factors - chiefly the size of your home and your average energy consumption. That being said, estimates can be made based on average household size and energy usage.
According to Ofgem, the average 2-3 bedroom home in the UK typically consumes 2,700kWh of energy over the course of a year. This equates to around 7.4kWh each day. With the UK's typical solar irradiance levels, a regular solar panel can generate around 1kWh per day. On this basis, the average sized house in the UK will typically need between 8 and 11 panels.
Of course, this is just a rough guideline. It’s important to also consider factors such as roof orientation, shading, and available space for installation. Indeed, a south-facing roof with minimal shading, for example, will typically yield the best results for solar panel efficiency in the UK. However, if this is not an option for your property, the panels you install may not be able to operate at optimum efficiency.
On the other hand, with advancements in solar panel technology happening all the time, higher efficiency panels and the use of integrated storage solutions like solar batteries can reduce the number of panels you may need. For this reason, before investing in this technology, it’s important you do your homework and select the best panels to suit your needs and property type. Indeed, it can be a good idea to consult with a solar panel expert, like Viessmann, before taking the plunge. Experts can assess your property, calculate energy needs, and propose an optimal solar system design tailored to your needs.
What different sizes of solar panels are available?
Solar panels come in a range of different sizes and power outputs. However, in the UK, the most common domestic panels have power outputs ranging from 250 to 400 watts. When it comes to physical dimensions, panel sizes vary. That being said, as you might expect, those with larger surface areas do usually produce more energy. For this reason when choosing the size of your solar panels, you need to think about factors such as available roof space and desired energy output.
How do you calculate how many solar panels you need?
To calculate how many solar panels you need, there are two factors you need to consider. These are:
1. Household energy requirements
First thing’s first - you need to assess your own energy requirements. While looking at UK averages can be helpful, at the end of the day every household's energy usage is different. Indeed, two identical houses may require a totally different amount of panels based on internal energy usage. So, work out your average annual energy usage and then calculate the amount of panels based on that. For example, if the panels you’re investing in have an output of 400W, ask yourself how many would be needed to cover your entire usage. If your household consumes a higher-than-average 4,000kWh of energy over the course of a year, you’d need at least 10 of these panels.
2. Roof space
As well as output capacity, you also need to assess the physical space you have available to you. With the average size of a single panel usually between 2 and 3m², try to calculate the maximum number of panels that could fit on your roof and see if this number would be enough to power your home. For example, if the panels you’re buying are 2m², and you need 10 panels to power your home, you need to ensure your roof is at least 20m² in size.
How many solar panels do you need to run a house off-grid?
Once again, the answer to this question is ‘it depends’. In order to power your home ‘off-grid’ through the use of solar panels, you’ll need to think about your household’s energy consumption, the efficiency of your solar panels, the efficiency of your household appliances and the amount of sunlight in your geographic location. However, as a rule of thumb, a typical UK household may need anywhere between 10 and 20 solar panels, each with an output of 350W or more, to meet its energy demands.
