3.5 kW Solar Panel System


A 3.5kW solar panel system will make you around £600 a year from energy bill savings and payments from the Feed-in Tariff scheme.

Costs of solar panels have plummetted over the last few years, with a 3.5kW system now costing around £5,000 on average.

You can compare prices from local installers in your area by filling in the form at the top of this page.



3.5kW solar systems

A 3.5kW solar panel system is a popular size for UK homeowners looking to install solar panels. This is one of the largest sizes that qualifies for the top rate of Feed-in Tariff payments, although there is a larger size that qualifies, a 4kW system.



How much will I save / earn?

With a 3kW system you can expect to earn around £600 a year. These earnings are made in three ways. Firstly, you will reduce your electricity bills by around 50% as you will be able to use the free electricity generated by your panels. Secondly, the Feed-in Tariff scheme pays you for generating renewable energy. Thirdly, you get paid for any spare electricity that you do not use which automatically goes back into the grid for others to use.

It’s worth noting that the future of the Feed-in Tariff (FiT) scheme is not looking good. In July 2015 the government announced they would be reviewing the future of the scheme in 2016 with an eye to either removing it or significantly removing it. However they did confirm that anyone who installs before 2016 will be guaranteed the FiT payments for 20 years.

So if you are considering installing solar panels, you will want to do it in 2015 while you are still guaranteed cash payments for 20 years from the FiT scheme. With solar costs at a record low, there is no better time to install.



How much will a 3.5kW panel cost?

You can expect to pay around £5,000 for a 3.5kW solar panel system. If you want to compare prices from local installers operating in your area enter your postcode in the form at the top of this page.

Click here to learn more about solar panel costs



a diagram showing how solar PV panels work

Will 3.5kW be enough for my home?

In most cases a 3.5kW system is plenty for the average home. In any case restrictions on the size of the average roof will mean that larger systems are simply not possible. It is also worth pointing out that larger systems are subject to different feed-in-tariffs making the 3.5kW size ideal for making the best return on your investment.

On its own a solar panel only provides a tiny amount of electricity and therefore it is necessary to connect many small panels together into one large one. For most solar panel types you will expect to see between 18 and 21 large panels on the roof. This amounts to around 25 metres squared of roof space. This is fairly standard although will depend on the type of solar panel you choose and the efficiency it offers. Solar panels are getting smaller and more efficient all the time.



What will the typical output be?

Over one year, the average output of a 3.5kW solar panel system is around 2800kWh. This depends entirely on the part of the country you live in, the direction of your roof, the amount of sunlight you get and any tree cover which may affect performance.

This output amount may not make much sense until we put that into context with the savings and earnings you could make.

The average home in the UK uses around 4,800 kWh each year, therefore you can see that you have already cut your energy bills by more than half. In addition you can expect to export around £60 worth of electricity to the grid when you are not using it. At current rates you can also expect around £400 worth of feed-in-tariff from your system.

When all of this is taken into account, you could possibly break even or even make money in a typical year. Obviously with energy prices increasing at such a rate this is an attractive proposition. If you home is especially efficient, with insulation and quality windows you can expect the return to be even better.

Learn more about solar panel output



Should I consider another size?

A 3.5kW system will deliver a healthy return on investment so is a very good option for homeowners. However a slightly bigger size up to 4kW is likely to deliver an even higher return on investment if your roof has enough space to install. You can view our guide on 4kW systems here.