When it comes to choosing the right solar panel system size, it pays off to do your research. A popular option for smaller households is to go with a 3kW solar panel system. This is just under the average installed solar panel system size in the UK, which sits around the 3.5 – 4kWh mark.
In this guide to 3kW solar panels, we’ll give you the details of this system size, its energy generation capabilities, associated costs and other crucial factors to consider before making your purchase. Whether you’re in the early stages of research or ready to make a decision, this article will provide you with the essential information you need.
What is a 3kW solar panel system?
A 3kW solar panel system is a renewable energy generating setup for homes to make their own electricity.
You’ll sometimes see kW (kilowatts) referred to as kWp (kilowatt peak) when reading about solar panels. In this instance, it means the same thing – the system’s theoretical power output under optimal conditions.
A 3kW solar panel system has all of the common features of any another photovoltaic (PV) panel system:
- Solar panels – Usually between 7 and 10 PV panels, depending on their individual wattage.
- Inverter – This crucial component converts the direct current (DC) electricity produced by your panels into alternating current (AC) that your home can use. For a 3kW system, a 2kW inverter is typically recommended.
- Mounting system– Securely attaches the panels to your roof.
- Electrical components – These include items like isolator switches, connectors and cabling to connect everything properly, including to your household system and the grid.
How many panels in a 3kW system?
The number of panels in a 3kW solar system can vary from one install to the next. It all depends on the individual wattage of the panels.
How many panels you go for depends on a number of factors. If roof space is limited, you might opt for fewer, higher-wattage panels to reach the 3kW. More efficient panels will help you produce more power in a smaller area, potentially reducing the number of panels needed.
However, it’s worth noting that higher wattage panels are more expensive due to their increased efficiency. A 450W panel, for example, will cost around 20% more than a 350W panel. Price differences also depend on the brand and overall panel quality.
Here are a few of the more common 3kW solar panel configurations:
- 10 x 300W panels – This setup gives you exactly 3kW of power.
- 9 x 335W panels – This combination slightly exceeds 3kW, providing 3.015kW in total.
- 8 x 375W panels – Gives you an exact 3kW system.
- 7 x 430W panels – Gives you 3.01kW of power.
How much electricity do you get from a 3kW system?
Going off the ‘nameplate’ rating, which is the number you see on the box, a 3kW system will give you 3kW of electricity an hour under optimal conditions. However, in the UK it’s far from optimal all of the time.
A 3kW solar panel system typically produces around 2,500kWh of electricity per year. This works out to about 85% of the system’s peak power output.
Breaking this down further, a 3kW system generates approximately 6.85kWh of solar-generated electricity per day on average. An average three bedroom home in the UK is said to use 2,800kWh of electricity per year, or 7.4kWh per day. As you can see, a 3kW solar system generates just under these figures on average. So, for a smaller 1-2 bedroom home, a 3kW would be a great size.
It’s important to take these figures with a pinch of salt as they are all averages. You also need to factor in that a 3kW solar panel system doesn’t consistently produce 7kWh every single day across the calendar. Solar energy production varies significantly with the seasons:
- Summer – You can expect peak production here, with your panels generating much more than 7kWh per day. At a conservative 3 peak sun hours per day, your panels can produce 9kW and more on good days.
- Spring and Autumn – Production levels are generally closer to the average.
- Winter – Generation drops significantly, often to around 10-15% of annual production.
Other factors affecting energy production include your location within the UK and your roof orientation. South-facing roofs perform best. East or west-facing roofs are not too far behind, but will produce around 15-20% less energy.
How much of your home’s energy needs will it cover?
A 3kW solar panel system is suitable for a smaller than average household. This is typically those with 1-3 bedrooms and 2-3 occupants. But it does all come back to how much energy you actually use.
For example, if you charge your electric vehicle at home or like to put three loads of washing through the tumble dryer each day, you’re going to be using quite a lot of electricity. To give you an idea of how much energy electrical appliances use in your home:
- Fridge: around 150W per hour
- TV: around 100W per hour
- Electric oven: between 1,000W and 5,000W per hour
- Electric hob: between 1,000W and 3,000W per hour
- Air-fryer: between 800W and 1,500W per hour
- EV charger: between 2.3kW and 7kW per hour
- Air source heat pump: Between 0.8 and 5kWh of electricity
An average 3kW solar system production of 6.85kWh will cover a large chunk of your energy needs, but it might not cover everything.
There is a caveat and that’s the fact that energy production and consumption aren’t always aligned. Your solar panels will only power these appliances when they are generating electricity.
This is where battery storage can play an important role. Residential battery energy storage systems can save up excess solar energy that you don’t use immediately. This is especially true during the summer months. The stored energy can then be put to use during the evening, overnight and first thing in the morning.
During winter months it’s a different story and you’ll likely need to rely more on grid electricity due to reduced solar generation. Despite this, a 3kW solar system can still significantly reduce your grid dependency throughout the year.
Should I have battery storage with a 3kW solar system?
Adding battery storage to your 3kW solar panel setup is an option worth exploring, but it’s not a one-size-fits-all solution. The decision largely depends on your specific energy usage patterns and how much excess electricity your system generates.
With a 3kW system, you may find that you’re not producing as much surplus energy as larger setups. This means the benefits of solar battery storage may be less obvious. The key is to assess how much energy you’re regularly feeding back into the grid. If it’s minimal, a battery might not be cost-effective.
However, if you’re often away during peak sunlight hours and use most of your electricity in the evenings, a battery could still be valuable. It would allow you to store your solar-generated electricity for use when you need it most, rather than drawing from the grid at higher rates.
Battery systems for 3kW solar setups typically range from 2-5kWh in capacity. Costs can vary from £2,000 to £5,000, depending on the size and quality of the battery. Whilst this is a significant investment, it’s worth considering if you’re looking to maximise energy and cost efficiency. There’s more information here on how to size battery storage for solar systems.
Before making a decision, it’s crucial to consult with a solar expert. They can analyse your energy production and consumption patterns to determine if battery storage would be a worthwhile addition to your 3kW system.
Cost of a 3kW solar panel system
To give you a good idea, you’ll pay in the region of £4,500 and £7,000 for a 3kW solar panel system in the UK. The panels, inverter, brackets, as well as the installation costs should be included in the total price.
The final price is also influenced by several factors, including panel quality, how difficult your roof is to access, the pitch of the roof, inverter type and if you want battery storage paired with solar.
It’s worth noting that whilst the initial cost may seem high, it’s important to view solar as a long-term investment. The savings on your electricity bills, potential earnings from the Smart Export Guarantee (SEG), and the increase in your property value can all contribute to offsetting the initial expense over time. You also won’t be buffered from sharp energy price hikes, which we’ve seen in the recent past.
To make sure you’re getting the best value for your money, it’s always advisable to get multiple quotes from reputable, MCS-certified installers. This will not only help you find the best price but also ensure you’re getting a good-quality system that will hopefully last you the next 30 years.
How long before you get a return on your investment for 3kW solar panels?
Investing in a 3kW solar panel system isn’t just about immediate savings – it’s about long-term financial and environmental benefits.
On average, homeowners with 3kW systems see their annual electricity bills drop by £200 to £500. This range largely depends on your household’s energy consumption habits and how they match up with your solar energy production.
There’s also potential to earn through the Smart Export Guarantee (SEG). This scheme pays you for surplus electricity fed back into the grid. Whilst rates fluctuate between energy suppliers, you could pocket an extra £50 to £100 yearly.
Considering these factors, most 3kW solar setups in the UK pay for themselves within 9 to 14 years. After this break-even point, you’re essentially generating free electricity for the remainder of the system’s life. And that lifespan is impressive. Solar panels often function efficiently for 25-30 years or more. Over a quarter-century, your cumulative savings could reach £5,000 to £15,000, factoring in potential energy price increases and system performance.
It’s worth noting that as general energy costs climb, your solar savings grow proportionally.
Space requirements and installation
When considering a 3kW solar system, you’ll need to account for about 12-17m² of roof area. The exact space required varies based on panel efficiency – more advanced panels can generate more power in a smaller footprint.
While south-facing roofs with a 30-40 degree pitch are ideal, solar panels can be installed on various roof types. Flat roofs require special mounting solutions to achieve optimal angles. If roof installation isn’t possible, ground-mounted systems are an alternative.
The installation process is relatively quick. From setting up scaffolding to final system testing, most 3kW installations are completed within 1-2 days.
Do you need planning permission for a 3kW solar system?
For most UK homeowners the answer is no, installing a 3kW solar system doesn’t require planning permission. It’s because solar panels more often than not fall under ‘permitted development’ rights. However, you may need to seek approval if:
- Your home is listed
- You’re in a conservation area
- The panels would extend more than 200mm from your roof’s surface
Is a 3kW solar panel system right for you?
A 3kW solar system can be an excellent entry point into renewable energy, particularly for UK homeowners with modest energy needs or limited roof space. These systems offer a balanced mix of cost-effectiveness and energy output, helping to lower both electricity bills and carbon emissions.
If your family grows in the future (and you have the roof space available), it’s possible to add-on extra panels to your existing system. It’s also possible to retrofit battery storage to your setup at a later date.
When evaluating if a 3kW system suits your needs, consider:
- Home size – Ideal for properties with 1-3 bedrooms
- Power consumption – Best for households using around 2,500-3,000 kWh annually
- Available roof area – You’ll need approximately 12-17m² of suitable space
- Costs – Initial costs range from £4,500-£7,000, but factor in long-term savings
If a 3kW system doesn’t align with your situation, explore alternatives. Smaller 2kW setups or larger 4kW+ systems might be more appropriate, depending on your specific circumstances.
