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What Size of Solar Panel Do I Need?

2017-06-19 23:49:06 Prostar Solar Read

Most residential solar panels have a size of between 1kW and 10kW as they qualify for the best feed-in tariff rate.

A 2kW system will take up approximately 14 sqm of roof space, while a 4kW will take up around 28 sqm. One square meter of solar panel could generate 150 watts of free power.

You can compare the prices of different sized solar panels offered by installers in your local area by entering your postcode in the form above.

What Size of Solar Panel Do I Need?

Solar Panel Sizes

Solar panel sizes for homes

The government's feed-in tariff, referred to as a government grant for installing solar panels, pays out based on the amount of electricity your panels produce. Therefore choosing the right panel size is an important decision.

As the feed-in tariff pays out the best rate for solar panel systems under 4kW, typical residential solar panel system will be sized between 2kW and 4kW. As the table below shows,a bigger system size will typically cost more but deliver a higher output leading to a higher return on investment.


Solar System Size
Approx. Roof Space
Typical Cost (£)
Typical Annual Output
Typical Profit Over 20 Years
1kW
8 sq m
2,500-3,000
850kWh
£650
2kW
14 sq m
3,000-4,000
1,700kWh
£3,800
3kW
21 sq m
4,000-6,000
2,550kWh
£5,635
3.5kW
25.5 sq m
5,500-7,000
2,975kWh
£6,050
4kW
28 sq m
6,000-8,000
3,400kWh
£6,750

If your house has a large roof you may want to consider a system even bigger than 4kW.

While a 4.5 to 5kW system will qualify for a slightly lower feed-in tariff rate, the additional power produced may still deliver a higher return on investment over 20 years. The cost of a 5kW compared to a 4kW isn’t significantly higher as you will not need to pay any additional labour time, scaffolding costs etc.

That said, if your roof only has space for a system under 4.5kW, you will probably be better off sticking with a 4kW or lower system and cashing in on the higher feed-in tariff rate.

For commercial use

Commercial solar panel systems tend to be much larger than residential solar panels. These sizes have their own bands for feed-in tariff payments. The upper bracket for the feed-in tariff is a 5,000kW system.

Learn more about commercial solar panels

Size of solar panels

The vast majority of homes’ roofs have adequate space for solar panels. A typical 1kW system will require around 8 square meters amount of space, whilst a typical 4kW system will require around 28 square meters.

Typical System Size
Typical number of panels
Typical roof area needed (sq m)
1.8
8
12.7
2.0
9
14.3
2.6
12
19.2
3.3
15
24
3.5
16
25.5
4.0
18
28.7


If you have too small a roof for the size of solar system you wish to install, you can buy more efficient panels which will take up less space. It’s important to note that higher efficiency tend to cost more.

The best thing to do is to discuss this with installers when they visit your home to provide a detailed quote.


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