4kW Solar Panel Systems (Guide)

In our guide to 4kW solar panel systems, we’ll be explaining everything you need to know before making a purchase including: 

• What property types are suited to 4kW solar panels
• How much they cost to install
• The amount of electricity you can expect to produce
• Annual electricity bill savings
• How much roof space you need
• A quick guide to DIY solar panels

In Summary: What You Need To Know About 4kW Solar Panel Systems

Short on time? Bookmark this detailed guide for later and read this short summary instead…

A 4kW solar panel system is suitable for the average 3-4 bedroom property in the UK. You can expect installation costs to be approximately £7,000 for standalone panels, and £11,000 with a suitable storage battery.

With this system in place, expect to generate enough electricity to be self-sufficient. This typically leads to savings of £600 or more per annum. 

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Before purchasing a solar panel system, you need to ensure you have sufficient roof space. Your panels can be fitted on both pitched and flat roofs, and you’ll need approximately 20 m²- 28 m² of roof space. 

DIY solar panel kits are available for those looking to save money on labour. Typically, these are suitable for small scale installations such as to power a workshop, or to be fitted on a motorhome. 

However, if you want to install a 4kW solar panel kit to power a house, we’d suggest using a MCS certified installer. An MCS installer will ensure your system is:

• Designed to be as efficient as possible, leading to maximum cash savings
• Using the highest quality components, with the longest warranty
• Installed inline with MCS standards
• Eligible for the Smart Export Guarantee (sell energy back to the grid)

Get prices on your system using an MCS installer by jumping over to our solar panel page here. 

Guide To 4kW Solar Panel Systems

Properties Suited To 4kW Solar Panels

A 4kW solar panel system is suited to the average 3-4 bedroom property in the UK with reasonable electricity demand. 

A system of this size is likely to consist of 10 panels or more, and produce in excess of 3,000kWh of electricity per annum. 

As you can see below, this covers the average household’s electricity demand, which is typically in the region of 2,700kWh.

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However, it’s worth noting that the majority of electricity that a 4kW solar panel system generates will be in daylight hours; they produce the most between 10am-4pm. 

On the flip side, the hours of highest electricity consumption for typical UK properties tends to be in the evenings. 

In order for electricity generated not to go to waste, you’ll need to ensure one or both of the below: 

• The system is hooked up to the grid so you can sell excess electricity via the Smart Export Guarantee
• Your system incorporates a solar storage battery, so electricity stored during the day can be used during the evening

How Much Does A 4kW Solar Panel System Cost?

Expect a 4kW solar panel system to cost £7,000-£8,000. 

The cost of installation will rise by approximately £5,000 when you incorporate a suitable storage battery.

Solar Panel System Costs

Solar panel system installation costs are affected by the likes of: 

• How big your system is and how many panels you need
• The quality of components and their warranty length
• The type (string, micro or hybrid) and quality of the inverter you use
• The type and size of the solar storage battery you use 
• Ease of access to the installation area

A 4kW system consisting of just solar panels (no battery) would sit in the region of £7,000-£15,000 depending on the installation complexity and quality of components. 

This could rise to £12,000-£20,000 when coupled with a suitable storage battery.

You can read our guide to solar panel installation costs here. Or, jump over to our solar panel page, and get prices for your setup.

Cost of A 4kW Solar Panel System With a Battery

The cost of a 4kW solar battery is likely to be in the region of £3,000, resulting in a £10,000 installation cost for a 4kW system including a smaller battery.

However, for many households this won’t be big enough and a 10kW battery would be more suitable. This is likely to add on £4,000 - £4,500 to the cost of an installation (depending on the manufacturer); £11,500 total cost including panels and labour for installation.

Due to the cost of a solar storage battery, as well as the fact they need to be replaced every 10-15 years, it’s worth spending the time determining if it’s a cost effective investment. 

If you’re using almost all the electricity from your 4kW solar panel system as it’s generated, or, selling back to the grid via the Smart Export Guarantee, you won’t need one. In this case, there’s nothing to be stored, and you’re maximising the energy produced by your solar panels.

However, if you’re not at home during daylight hours, it’s likely a solar storage battery is the right option. You’re not able to use electricity as it’s generated and without using the Smart Export Guarantee (selling energy back to the grid), it will go to waste.

You can read more about solar panel battery storage here. Or jump over to our solar panel page to get a quote on your system, with and without the cost of a battery.

How Much Electricity Will A 4kW Solar Panel Kit Produce?

A typical 4kW solar panel system will generate over 3,000kWh of electricity per year. Assuming you use this electricity as it’s generated or use a solar storage battery, this will mean your property is self-sufficient.

However, it’s important to note that some household appliances bump this average dramatically. If you use either an air source heat pump or an air conditioning unit, your electricity consumption is likely to be a lot higher than the average of 2,700kWh per year.

Lots of variables contribute to exactly how much energy your solar panels produce and their efficiency including: 

• Roof pitch
• Shading from trees or buildings
• Roof orientation 
• The type of inverter you use
• Capacity of your solar panel system (kW)
• The list goes on!

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Our guide to roof suitability for solar panels here explains how these variables affect total electricity produced.

How Much Will You Save With A 4kW Solar Panel System?

A 4kW solar panel system is likely to save your household £500-£600 per year. This assumes you sell any excess electricity back to the grid via the Smart Export Guarantee. 

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However, these savings are amplified if you use a storage battery. The Smart Export Guarantee pays a lot less per kWh than you’ll pay per kWh if you need to buy back from the grid. 

Put simply, you don’t want to sell electricity back to the grid only to buy it back later. Using a solar storage battery will ensure that your property is self-sufficient and you don’t need to buy electricity back from the grid.

How Much Roof Space Do I Need For Solar Panels?

Solar panels aren’t exactly small, and before deciding on whether a 4kW system is suitable for your home, you need to check if you have the space. 

A typical 4kW solar panel system will need around 20 m²- 28 m² of roof space. Flat roof space can be used if it’s solid (i.e. a single storey extension). 

If you’re unsure on whether your roof is suitable for solar panels you can read our guides here: 

• Fitting solar panels on a flat roof
• Roof suitability guide for solar panels

Or, jump over to our solar panel tool which highlights the best place to install your solar panels, and how much space is needed. 

4kW DIY Solar Panel Kits

Whether you’re a homeowner, or looking for an offgrid installation, there’s a suitable DIY solar panel kit out there.

Can I Fit Solar Panels Myself?

If you’re in the need of an offgrid system for the likes of a motorhome, DIY installation is the way to go. 

However, if you’re wanting to fit a substantial system to power your home, you’ll want to use a MCS installer. 

Not only do MCS certified installers use high quality components and work to industry standards, they enable your solar panel kit to qualify for the Smart Export Guarantee. If you don’t use a MCS installer, you won’t be able to sell energy back to the grid!

Read our guide to solar panel installers here, or jump over to our solar panel page to get a quote. 

How Much Do They Cost?

DIY solar panel kits are cheap for two reasons: 

• Labour costs for installation aren’t included
• Components used can sometimes be lower quality than what an MCS installer would use, coming with a much shorter warranty

Expect a 4kW DIY solar panel system to cost around £5,000 without a battery.

Our opinion? Small setups to power low powered appliances in a workshop or even a motorhome are perfect to install on a DIY basis. For anything else, you’ll want installation completed by a MCS professional.

Get prices on a 4kW solar panel system installed by a MCS professional by jumping over to our solar panel page here. 

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