Ultimate Guide to 3kW Solar Power System [2025 Update]

In recent years, solar panels have become a hot topic as people continue to focus on sustainable energy solutions. Did you know you can save money and improve your home's energy efficiency by installing only a 3kW solar power system? For some UK homes with low electricity consumption, a 3kW solar power system is enough.

In this guide, we will explore what a 3kW solar power system is, how much it costs, how many solar panels it needs, and whether it is worth it. Moreover, suppose you think solar power systems cost too much. In that case, you can consider a portable solar system, like Jackery Solar Generator, which combines Jackery Solar Panels with a Portable Power Station to turn sunlight into electricity. Wall sockets and carports can also recharge the power station on cloudy or rainy days. 

What Is a 3kW Solar Power System? 

Before we delve further into the 3kW solar power system, we must understand what kW means. In simple terms, kW is a unit of measurement for the power a solar power system can generate or use at a specific moment. Similarly, kWh is a unit of measurement for the energy generated by a 3kW solar power system over time.

Therefore, a 3kW solar power system has a peak output rating of 3 kilowatts, which means it can generate 3,000 kWh of electricity per year under standard test conditions.

However, this does not mean your 3kW solar power system will automatically generate 3,000kWh of electricity annually. Solar power systems' output is affected by many factors, such as sunlight hours, the angle of the roof, and the installation standards.

What Does a 3kW Solar Power System Consist of, and How Does It Work?

A 3kW solar power system usually includes solar panels, controllers, inverters, and batteries. The following will detail its composition and working principle.

Solar Panels: A 3kW solar power system usually consists of multiple solar panels. The solar panel is the system's core component responsible for energy conversion (converting solar radiation energy directly into DC power).

Solar Controller: The controller can also adjust the working state according to environmental conditions to optimise system efficiency.

Inverter: When it is needed (most household appliances require AC power), the inverter will play the role of energy inversion (converting DC power into AC power).

Battery (Optional): When there is sufficient sunlight, the solar panel's power will generate excess power in addition to immediate use. However, the excess power will be wasted if the system is off-grid and has no battery storage.

Other Components: Other solar power system components include the mounting structure (which supports the solar panels on the roof), cables, junction boxes, MC4 connectors, saddles, lugs, etc.

Is a 3kW Solar Power System Enough for a UK household? 

In the UK, you need to consider how much a 3kW solar power system can generate and what it can power. If the household energy consumption far exceeds the power generated by the solar power system, we also need to consider whether it needs to be equipped with energy storage batteries.

Power Generation of 3kW Solar Power System

According to the rating, a 3kW solar power system can generate 3kW of electricity per hour under optimal conditions. However, a 3kW solar power system in the UK is not always at its best, so it usually produces 85% of its peak power output (estimated value).

Under typical irradiance in the UK, a 3kW solar power system can generate about 7kWh of electricity per day and up to 2,550kWh of electricity per year. However, the above are averages, and you must consider other factors affecting solar panel output.

Other factors that affect the amount of electricity a 3kW solar power system can generate:

• The efficiency of the solar panels

• The tilt of the solar panels

• The orientation of the roof

• The season (number of hours of sunshine)

• Latitude (different parts of the UK)

What Can a 3kW Solar Power System Power?

The UK's 3kW solar power system has considerable power generation capacity and can reliably supply electricity for various devices and scenarios. Generally, a 3kW solar power system can meet the daily power needs of a small—to medium-sized household, such as running essential appliances such as refrigerators, lighting, televisions, computers, and small—to medium-sized kitchen appliances.

A 3kW solar power system can power all the following devices for a specified period and still have some power left over.

In summary, a 3kW solar power system generates an average of about 7kWh of electricity per day, which will meet most of the power needs of an average UK household. However, it may not meet all of your power needs. For example, if you charge your electric car at home every day or use an electric shower for two hours daily, a 3kW solar power system will not generate enough electricity.

Therefore, a 3kW solar power system is best suited for a small home with 1-2 bedrooms and an annual electricity consumption of about 1,800kWh (Data Source: Ofgem). People with more significant properties will need a solar power system to provide more electricity. For example, someone with a larger house with 5-6 bedrooms may need a 6kW or even larger solar power system.

How Many Solar Panels Are Needed for a 3kW Solar Power System?

In the UK, if you want to install a 3kW solar power system, you usually need to consider two factors, namely the power and area of the panels, to determine the number of panels required.

First, how many solar panels are needed to build a 3kW solar power system depends entirely on the peak power rating of a single solar panel. To calculate the number of panels required for a 3kW solar power system, we can use the following steps:

Step 1: Determine the Power of a Single Panel

In the UK, the market's power range of standard residential solar panels is between 250 watts and 400 watts (0.25kW-0.4kW).

Step 2: Calculate the Number of Panels Required

3kW ÷ 0.25kW/piece = 12 pieces

3kW ÷ 0.4kW/piece ≈ 8 pieces

Therefore, 8 to 12 panels are required to form a 3kW solar power system. However, higher-power solar panels are usually more expensive due to their increased efficiency. Here are some of the more common numbers of solar panels for 3kW solar power systems:

The above is for reference only. Please consult a professional installer.

Step 3: Analysing the Number of Solar Panels According to the Area

A typical solar panel area is 1.7 square meters (1 meter x 1.7 meters). A 3kW solar power system usually requires 8-12 solar panels.

1.7 square meters/piece × 8≈14 square meters

1.7 square meters/piece × 12≈21 square meters

Therefore, the roof area required for a 3kW solar power system is about 14 to 21 square meters. However, this is just an estimate because the inclination of the solar panels also affects the roof area.

Higher-power solar panels can help you generate more electricity in a smaller area, which may reduce the number of solar panels required. Therefore, if the roof space is limited, choose a higher-power and fewer solar panels to achieve 3kW of power.

Cost of 3kW Solar Power System in the UK

On average, the total price of a 3kW solar power system in the UK (panels, inverters, brackets and installation costs) is usually £4,500 to £5,500. If you want to add batteries to the system, the price will increase by £2,500 - £3,500, and the total cost will be £7,000 to £9,000.

The total cost of a 3kW solar power system is mainly composed of the following parts: (The following data are all estimated values and are for reference only.)

(Data Source: whatcost.co.uk)

Factors Affecting 3kW Solar Power System

However, the above prices and costs of 3kW solar power systems are all estimated values. The final price of a 3kW solar power system will also be affected by the following factors:

Location

Quotation from the installer

Roof type and area

Brand

Type of solar panels and their efficiency

Whether batteries are required

How Can the Cost of a 3kW Solar Power System Be Reduced?

In recent years, the UK government and local authorities have provided several financial incentives (such as solar panel grants and schemes) to encourage the use of renewable energy, especially solar power systems.

These grants are intended to cover some of the upfront costs of installing solar panels and, in some cases, the installation cost. Here are some of the leading solar panel grants and solar schemes currently running in the UK:

Direct Grants

The following are grants the UK government provides to ease the installation cost of installing a solar power system.

• ECO4

• ECO Flex

• HUG2 (expires March 2025)

Special Grant Schemes

The following solar schemes offer benefits beyond a simple grant (reducing the initial cost of a solar power system).

• 0% VAT on Solar Panels

• SEG (FiT alternative)

• Solar Together

Solar Grants and Schemes Elsewhere

In addition to government solar grants and schemes in the UK, local authorities offer other grants and schemes tailored to their needs.

• Home Energy Scotland Grant and Loan (HESGL)

• Welsh Government Warm Homes Nest Scheme

• Ireland solar panel grants and schemes

However, please note that applying for these grants is not always straightforward, as each has its eligibility criteria.

Jackery Solar Generators Explained

Considering the higher costs of a 3kW solar power system, ranging from £7,000 - £9,000 and even more, including the batteries, installation, maintenance, etc., we highly recommend the solar generator - a portable solar system - to try solar energy first.

Solar generators have many benefits. For environmentally aware users, they are essential since they produce clean electricity without emitting the same pollutants as traditional gas or diesel generators. Once they are up and running, they have very low operational costs. Fuel doesn't need to be purchased, and because they have fewer moving parts, they typically require less maintenance.    

We recommend Jackery Solar Generators, which combines Jackery Solar Panels with Portable Power Stations to create a portable solar set. Jackery offers portable power solutions ranging from 99W to 12 kWh, capable of powering up to 99% of appliances, including washing machines, refrigerators, microwaves, etc.      

Also, the Jackery Portable Power Stations are compact and easy to carry, so you can put them everywhere in your home or on your outings. Compared to gas or other traditional generators, they are safer to use, and you can even use them while sleeping.

Jackery Solar Generator 2000 v2

Jackery Solar Generator 2000 v2 combines Explorer 2000 v2 portable power station and SolarSaga 200W solar panel. It has a 2042Wh capacity and a 2200W power output, enough to power most appliances at home or outdoors during camping, RVing, and off-grid living.

With its remarkable 2042Wh capacity and 2200W output, the Jackery Explorer 2000 v2 Portable Power Station can power most home appliances. Additionally, it has two AC outlets, one USB-A 18W connector, and two USB-C ports (100W + 30W), enabling you to charge numerous devices simultaneously, including laptops and phones.

At approximately 38.6 lbs or roughly the weight of a suitcase, it is the first 2kWh LiFePO4 power station in the world with cutting-edge EV-grade CTB (Cell to Body) Structure technology⁵. It is the ideal power source for camping, road trips, and off-grid life, and it has a collapsable handle for convenient carrying.

The CTB structure allows for a compact, potent design, increasing space efficiency to 59%. Its 13.2 × 10.4 × 11.5-inch size, similar to a medium printer, makes it easy to fit in your car.

It has demonstrated resilience even in earthquakes up to 9 by passing the demanding IEC60068-3-3 seismic test. You may feel secure knowing it can manage bumps, falls, and challenging circumstances wherever you go because it is drop-resistant and built to withstand the unexpected.

The Jackery SolarSaga 200W Solar Panel can increase solar conversion efficiency by up to 25%. It has a long-lasting ETFE-laminated case and adjustable tilt for optimal sunlight absorption. Ideal for home backup and outdoor excursions, this device is lightweight, foldable, and simple to connect to a power source.

(*The working hours are only for reference; the actual working hours depend on your usage.)

Jackery Solar Generator 1000 v2

The Jackery Solar Generator 1000 v2 integrates the Explorer 1000 v2 portable power station with a SolarSaga 100W or 200W solar panel. Compared to the Solar Generator 2000 v2, this one is lighter and more suitable for small appliances.

With a phenomenal 1500W output—50% more than previous generations—the Explorer 1000 v2 portable power station can efficiently run high-demand necessities like portable air conditioners, kettles, and freezers. It is the perfect partner for all your power demands because it has USB-A/C connections and can simultaneously charge several devices (laptop, phone) with up to 100W dual PD charging.

When your battery gets low, the Explorer 1000 v2 Portable Power Station may be fully charged in less than an hour thanks to the Emergency Charge Mode, which is activated via the app. Furthermore, battery life can be increased by charging from 0% to 100% in just two hours using an AC wall outlet.

With the Jackery 1000 v2, you can be ready for any emergency. During blackouts, charge vital gadgets like your radio, phone, and medical equipment. You can easily handle unforeseen circumstances thanks to the Jackery 1000 v2's higher capacity and flexible output options.

Experience improved performance and reduced weight with this cutting-edge solar solution. With its all-black design and cutting-edge IBC technology, our 100W bifacial high-efficiency (up to 25% conversion rate) solar panel generates more power without adding weight. This panel guarantees optimal sunlight absorption and additional energy yield from the rear due to its optimised cell structure and lack of front shading.

(*The working hours are only for reference; the actual working hours depend on your usage.)

Is a 3kW Solar Power System Worth It in the UK?

In recent years, solar power systems have become the choice of increasing families and businesses. So, is it worthwhile for British families to install a 3kW solar power system? The article below will analyse this question from economic and environmental perspectives.

Economic Considerations

The initial installation cost of a 3kW solar power system is about 4,500 to 5,500 pounds. Although this cost is relatively high, it can significantly reduce the household's electricity costs.

An average British household can save at least 450 pounds in electricity bills annually with a 3kW solar power system. In addition to recovering the initial investment (approximately) over the life of a 3kW solar power system of at least 25 years, you may also make a profit of at least 11,250 pounds. If you choose to join SEG, it will shorten the time to recover the initial investment of a 3kW solar power system.

Installing a 3kW solar power system can also indirectly increase the value of your home. For example, Rightmove found in its 2023 study that increasing a property's EPC from D to C can increase its value by an average of about 3% (£11,157).

Environmental Considerations

With the growing awareness of environmental protection, installing a solar power system can save households money and contribute to protecting the environment. For example, using solar power systems to generate electricity can reduce dependence on fossil fuels, especially greenhouse gas emissions.

UK households (28.2 million) account for 26% of the UK's total emissions (3.5 tons per year). Based on Sunsave data, a 3kW solar system can reduce carbon dioxide emissions by about 1.1 tons per year (one-third of the annual carbon emissions of an average household).

Based on the above analysis, it is economically attractive for British households to install a 3kW solar power system, especially in the long term. Solar power systems can also bring significant environmental benefits to households. Therefore, installing a 3kW solar power system is worth considering for British households with financial means.

Does the Installation of a 3kW Solar Power System Require Planning Permission?

For most UK homeowners, installing a 3kW solar power system does not require planning permission. Solar panels are part of residents' "permitted development" rights in the UK.

However, you may need to seek approval from your local planning authority (LPA) if the following situations occur:

The first situation is where planning permission is required.

Prior approval may be needed if you install a solar power system in a conservation area, flat roof, national landscape, or world heritage site.

In addition, solar power systems installed on roofs and walls must not protrude more than 200mm above the roof or wall surface to reduce visual impact. If solar panels are installed on a flat roof, their height must not exceed 0.6 meters above the highest part of the roof.

The second situation is where planning permission is required.

Planning permission is usually necessary to install a solar power system on the ground. However, if the solar power system (only one) you install is within an area of ​​9 square meters, does not exceed a height of 4 meters and is at least 5 meters from the property boundary, then planning permission may not be required.

The third situation is where planning permission is required.

If you install wall-mounted solar panels, you must ensure they are structurally safe, minimise visual impact, and comply with building regulations.

However, please check whether you need the appropriate planning permission before installing a solar power system. Solar panel planning permission requirements may also vary in different parts of the UK. If you live in Scotland or Northern Ireland, please visit mygov.scot or nidirect.gov.uk.

In addition, even if planning permission is not required, you may need to comply with relevant building regulations. Therefore, please consult a solar expert or installer in advance.

FAQs

The following are the frequently asked questions about the 3kW solar power system in the UK:

1. How many solar panels are needed for a 3kW solar power system?

If each solar panel has a power of 250W to 400W, then 8 to 12 solar panels are needed. The specific solar panel configuration of a 3kW solar power system depends on your unique needs.

2. How do you determine if a 3kW solar power system suits you?

A 3kW solar power system is a relatively cost-effective and energy-efficient renewable energy source that can help reduce electricity bills and carbon emissions.

However, please consider the following aspects to determine if a 3kW solar power system suits you: power consumption, house size (1-2 bedroom house), available roof area, and cost. A 3kW solar power system suits UK homeowners with moderate daily power needs or limited roof space.  

3. Which is better, a 3kW or 5kW solar power system?

The most significant differences between a 3kW and 5kW solar power system are power generation and cost.

In the UK, a 3kW solar power system can generate an average of 2,550kWh of electricity per year, while a 5kW solar power system can generate an average of 4,250kWh.

In addition, the average cost of a 3kW solar power system in the UK is between £4,500 and £5,500, while the average cost of a 5kW solar power system is between £7,500 and £8,500.

In short, a 5kW solar power system is more suitable for households with high budgets and electricity consumption. For British households with low electricity consumption and limited budgets, a 3kW solar power system is better.

Final Thoughts

In the UK, a 3kW solar power system can meet the daily electricity needs of ordinary households, including lighting, air conditioning, refrigerators, televisions, and other electrical appliances. Therefore, it is an ideal sustainable power supply for tiny houses with 1-2 bedrooms. However, before deciding to use a 3kW solar power system, families should also consider factors such as the house's orientation, the roof's tilt angle, and local climate conditions.