Best 4kW Solar PV System & Installation UK

Last updated: January 20, 2024

A 4 kWp Solar system is one of the most common size solar system in the UK, but did you know a solar battery can allow you to use around 30% more solar energy?

Typically composed of around 12 solar panels, the 4 kWp solar system is not only a source of producing renewable energy but also saves you on electricity bills.

But did you know without a battery, 50% of the energy your solar panels generate is returned to the grid?

A solar battery allows you maximise the benefit of the solar system by allowing you to store surplus electricity being produced in the daytime to be used at night time or on a cloudy day.

For example, in a house where all residents go to work, the solar system with solar batteries would allow you to benefit from the energy in the evening when you are all at home.

In this scenario, the total amount of energy being produced by solar panels during the day will be stored by solar batteries and would be readily available to be used in the night time. 

On the other hand, in a house where all persons work from home, the solar batteries will use the energy as it is produced with nothing stored for the night.

Therefore, there will still be a considerable reliance on grid electricity.

kWp* stands for ‘kilowatt peak’. This is the amount of power that a solar panel or array will produce per hour in ideal conditions.

Solar Battery Storage Key Points:

  • A 4 kWp solar system is one of the most common solar array size in the UK.
  • It is typically used for a 4+ bedroom home with 2–3 tenants.
  • It typically requires around 12 solar panels.
  • Without a solar battery, approximately 50% of the energy your panels generate is not used.
  • A solar battery allows you to use around 30% more solar energy.

Improving the efficiency of 4kW panel setup?

A 4kW panel set-up will only give you benefit in terms of savings and performance if it is working with maximum efficiency.

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A PV set-up with bad functioning will not be able to convert the optimal amount of solar energy into electricity. 

There are many factors that contribute to maximising the efficiency of solar panels by increasing their performance and productivity:

Buying an efficient solar panel brand

Unfortunately, solar panels, also known as photovoltaic systems (PV) use semiconductor technology to convert electricity from sunlight to electricity.

Unfortunately, it could not convert all the energy they receive from the sun into electricity.  

Lately, many brands emerged in the market that can convert up to 22 per cent of sunlight into electricity for use.

These brands include names LG, Sunpower, Panasonic, Silfab, Canadian Solar, Trina Solar, Q Cells, Mission Solars, REC Solar and Windy nation.

Check our quick help solar energy guides here:

Angling/ positioning of Solar Panel 

The direction of solar panels is the most important factor in their maximum productivity. In the UK, solar panels must be exposed to sunlight from 9 am to 3 pm. 

You can get the maximum benefit from the solar panels if your roof is south-facing.

According to Stanford University, a 34-degree roof tilt angle is the best position for maximised performance.

Occasional Cleaning of the Surface 

Fortunately, Solar Panels require little maintenance. A thick layer of dirt on solar panels can result in a 5% decline in their efficiency.

In the areas with less rain, this percentage could go up to 20%. It is best to keep up with their maintenance by cleaning the PV surface once a year.

Avoid PV installation in Shady areas

Shades from tall trees or big buildings can seriously harm the electricity output from your solar panels.

If even one photovoltaic cell is shaded, it can impact the energy generated by its neighbour cell. This is because it acts as a resistor.

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Expert installation

It is best to get hire the services of an expert i.e. MCS certified installer to install Solar panels as a small mistake can lead to its poor performance.

There are certain technicalities regarding the positioning and temperature of PV panels that only an expert can deal with.

For instance, solar panels should have an angle between 18 to 36 degrees for maximum sunlight exposure.

Also, the gaps between the solar panels and the roof are determined by the temperature to prevent the panels from overheating.

Does a 4kW solar system actually save money?

A solar panels coupled with solar battery storage allow you to use around 30% more solar energy.

According to Energy Saving Trust, a household using 4.2 kW can save between £165 to £405 off bills at the current energy prices. 

Solar pays for itself over the year

To be fair, there is no quick way to get a return for the considerable investment you have made in the installation of solar panels and solar battery storage.

However, you will be saving a good amount of money by the reduction in your electricity bills.

For Instance, your 4kW solar panel will cost you around £4,000 to £6,000 and generates up to 4.8% profit over time of 20 years.

Looking from this perspective, your solar panels and solar battery storage system will be paying for themselves over the span of a few years.

The Smart Export Guarantee

The Smart Export Guarantee (SEG) is a government-backed initiative that requires electricity suppliers to pay small-scale generators for the renewable electricity being exported to the national grid. 

In SEG you can get up to 12p per kWh in return for the renewable electricity you export to the grid.

This scheme can be more beneficial if you have solar battery storage installed with your panels. Your solar battery would store the excess electricity that can be exported to the national grid.

Energy Saving Trust estimates an average household could make between £80 to £110 (based on 3.99 per kWh) by the SEG scheme.

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Solar increases the value of your home

A survey carried out by ING Direct suggests that solar panels are one of the most desired extra features of a home.

So if you are planning to sell your house with the solar panels installed, rest assured you are going to get a good offer for it.

This research finding is also backed by a government report that says fitting solar panels can increase house prices by up to 14%. 

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Benefits of installing a 4kW solar system

Despite having a high upfront cost, a 4kW solar system has many benefits that should be taken into consideration before making your mind up.

The benefits of installing a 4kW solar system include the following:

Reduces your carbon footprint 

According to an estimate, domestic solar panels could save around one tonne of CO2 per year, which means just one installation can offset 25 tonnes of CO2 over its lifetime.

Saving Money

You can experience a significant reduction in your electricity bills by incorporating a PV system into your household.

Not only that, but you can also earn a small amount of money by exporting excess electricity to the national grid under the SEG scheme.

Low Maintenance

Solar panels have a life span of 25-30 years with a possibility of changing the inverter after 15 years.

Other than that you will only need to clean the surface of the panels after a year. However solar battery storage may need replacement after 7 to 10 years depending on their type.

Year-round efficiency

Although solar panels work best during the summers yet they produce a considerable amount of electricity in winters too.

Better Control on energy usage

Installing solar panels enables you to have better control over energy usage.

For Example, You will know how much electricity you can use in a 4kW solar set-up.