Wouldn’t you like to generate free electricity for use in your home, or to export to the UK National Grid? It seems like a dream come true, doesn’t it? Well, this is something you can do quite easily, with a little help from some photovoltaic (PV) solar cells. But, how much do solar panels cost? And, how large must the solar panel system be?
Photovoltaic technology continually advances. And, it’s now commonplace for householders to install a system on their roof. But, many people find that solar panel installation costs are too expensive. However, if you plan correctly, and can afford the initial outlay, you will provide savings on your energy bills. And, in the long run, might even make money too.
On average, solar panels cost between £1800 and £6100 in the UK. The most common size for domestic solar panels is a 4kWp system.
Most solar PV panels produce around 250Wp. Therefore, to produce 1kWp, you’ll need 4 panels. So, for 4kWp you’ll need 16 panels arranged into an array.
(By the way, you probably noticed we measured the power output of a PV cell in kWp (kilowatt peak). This is the amount of energy generated at peak performance during the summer).
But, why are PV panels popular? Let’s start by stating the obvious. Solar energy is clean, and once the receptor array is set up, it needs very little maintenance. Probably, the most important maintenance is to keep the panel surfaces clean. Otherwise, your power output will substantially decrease.
Next, another obvious advantage is that your energy bills will decrease. And thirdly, if you produce more than you use, you’ll see an extra income trickling in from sales to the electricity suppliers.
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Main Topics
Cost of Solar Panels
The following table can be used as a monocrystalline solar panel cost calculator. Here, we’ll explore different solar installation system sizes, the amount you’ll save on your energy bills, and how much you can expect to pay. However, the estimates listed in the table are intended to be an indication only. As you’ll see later on, the actual power output varies depending on various factors.
Remember, VAT on solar panels is 5% at the time of writing.
| Solar panel system size | No. of panels | Cost | Annual electricity output | Annual estimated electricity savings |
|---|---|---|---|---|
| 3kWp | 12 | £6000 | 2550kWh | £160 |
| 4kWp | 16 | £8000 | 3800kWh | £270 |
| 5kWp | 20 | £9000 | 4250kWh | £320 |
| 6kWp | 24 | £10000 | 5100kWh | £430 |
For London & SE areas, you can add on ~20% to the quote.
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What does this mean?
To put this data into context, let’s assume we have a 3 bedroom property. For this sized family, we’ll need either a 3kWp or 4kWp system costing between £5500 and £6100. At the present level of technology, a 3kWp system uses around 20m2 of roof space, while a 4kWp system needs about 25m2. Furthermore, to help you along here, a 3-4kWp array gives our fictitious family about 3000kWh per year and contains 12 to 16 panels.
Now, let’s assume the cost of solar panels for a 3 bedroom house totals £6000. Typically, to buy the panels costs about 80% (£4800) of the total, while 20% (£1200) goes towards fitting the solar panels. Moreover, the installation, using two specialists, will take between 2 and 4 days depending on the roof’s accessibility and condition.
Similarly, let’s consider a family of 2 adults and 1 child living in a small terraced house. With a roof area of between 14m2 and 20m2.
So, the area accommodates a 2kWp to 3kWp photovoltaic system producing about 1700kWh to 1550kWh of solar power for the home. Furthermore, the total cost of this system will be from £4000 to £5000 and take between 2 and 3 days. Also, the cost of the solar PV panel array will be between £3500 and £4000 with the installation costing between £500 and £1000.
Solar panel prices have been steadily falling over the years. According to a Which? survey, the average amount paid for a 3.6 to 4kWp PV panel system before 2015 was over £9000. In the following 3 years up to 2018, the average cost dropped to around £6600. However, the UK Government’s Department for Business, Energy and Industrial Strategy published statistics that showed the cost per kW of solar electricity stayed consistent between April 2017 and March 2019.
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Solar Panel Pricing Factors
The various factors affecting the solar panel costs can be summarised as follows.
The efficiency of the panel
The best solar panels are those that produce the largest proportion of usable electricity. This means the best panels depend on the size of your roof and which direction it’s facing. If you have a small roof, you’ll need a small solar panel that produces as much power per square metre as you can afford. With present technology, the best solar panels achieve about 23% efficiency. With the average being between 15% and 18%.
Actual sunlight hours for your location
This is a function of how long your day is and what latitude you live at. For example, if you live in the North of Scotland, you’ll have shorter days in the winter than the far west of Cornwall. Conversely, Scotland has longer daylight hours in the summer than Cornwall. Similarly, if you live in the far north, the sun will be nearer the horizon than in the south. So, will be providing less light energy for the panels to collect The power output calculated from this data will help you decide which type of PV panels you should consider.
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The pitch of your roof
Although you can generate power with a roof of any pitch angle, the optimum is between 10 and 60 degrees. So, within this range, you will achieve the best return for your money.
Does your roof point face south or not?
As you would expect, pointing due south is the best direction for the array to face and generate the maximum possible electricity. However, if you can’t manage that, it’s possible to generate substantial amounts of electricity with an east or west–facing slope. So, a south–facing array will give the best power production and a better return on your investment. But, you can achieve a good return in any direction except north.
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Number of panels
If you buy more panels, you’ll have a larger PV array. So, if a 4kWp array has about 16 panels. You can then calculate how many panels you need to generate a set amount of electricity. This will be a useful thing to know if you intend selling excess power to the National Grid.
You can also choose fewer panels of higher quality, higher efficiency cells and still get the same electricity production as using the lowest efficiency, and cheapest solar panels. Usually, if you have a large roof, it’s generally, more cost–effective to choose the low–efficiency option. However, you are limited to the size of the PV system, that will fit on your roof. If you intend buying a 4kWp PV system using high–quality cells you will need a roof area of at least 21m2. Whereas, low–quality cells will need at least 28m2. If in doubt, speak to a qualified installer about your options.
Type of PV cell
Although a PV cell is made from layers of semiconducting silicon covered in glass, there are different grades of cell, depending on the type of glass and the silicon. At present, there are two basic types of solar cell.
- Monocrystalline panels are currently the most efficient. And, therefore the most expensive. They convert more energy, can use lower light levels and are more durable than the other type. Also, because they are more efficient, you need fewer of them. And, they take up less space on your roof.
- Polycrystalline panels are cheaper to produce. So, are cheaper for us to buy. But, they have disadvantages. Compared to monocrystalline cells, they are less efficient when converting sunlight into electricity, and less durable.
As well as the glass panels that many people have on their roof, there is another variation.
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- Solar tiles are the same size as typical roofing tiles and can be fitted alongside existing roof tiles. Although they look good, compared to traditional solar panels they tend to be less efficient and more expensive to purchase and install.
You can also vary the type of glass covering the cells. You can use
- Plate glass is a standard option and cheaper than the other.
- Whereas, strengthened glass is more durable and less likely to be damaged. This type can even increase the efficiency of the solar cell beneath.
However, you have no control over many of these factors, except to move house or rebuild. This is when the specialist professionals will survey your property’s location and provide a custom–designed photovoltaic panel system. In the meantime, you must make do with the generalised information worked out from the solar PV calculator shown earlier.
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Solar Panel Installation Costs
If you intend taking advantage of the financial help or want to sell the electricity to the National Grid, you must use equipment from an MCS certified manufacturer and use an MCS (Microgeneration Certification Scheme) installer. This ensures that everything is specified, manufactured, installed and maintained correctly. You can check that the companies you deal with are MCS registered by using this search tool on the MCS website.
As always, installation charges will vary depending on where you live in the country. Having said that, the average MCS certified solar panel installer charges between £150 and £200 per day. Unless you are very unlucky and need major alterations to your roof, most jobs won’t take longer than about 3 to 4 days. This duration might also vary if you have difficulties accessing the roof.
All installation companies will need scaffolding to provide a safe working platform. Once that’s in place it‘s usually very simple for a professional to install the panels. By the way, make sure you are clear about who is organising the scaffolding, and whether the cost is included in your quote.
The type of roof you have is an important factor that will alter the installation cost. For example, An installation on a flat roof will cost less because it’s easier to access than a pitched roof. Another factor is if you have a very high roof. Very high roofs are more difficult to work on and more dangerous. So, you’ll find that installers charge at the top end of the day rate range.
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Additional costs
There are additional costs which must be included within the overall quote. And, some have to be factored in at a later date, such as repairs and cleaning.
| Additional factors | Average costs |
|---|---|
| Solar battery storage | £1000 to £6000 |
| Inverter | £1000 to £15000 |
| Roof repairs | £100 to £1000 |
| Scaffolding | £20 to £40 per day |
| Water tank | £2000 to £4000 |
| Solar panel cleaning | £10 per panel (subject to a minimum charge) |
| Panel repairs and maintenance | £120 to £500 per panel |
Installation – step by step
The panels will already have been assembled by the manufacturer in their factory. So, all that’s needed on–site, is for the installer to:
- Screw roof anchors onto the structural roof timbers. The style and strength of these will depend on the characteristics of your roof, potential snow loading, type of roof tiles, and locations of the rafters. They will be made from either aluminium or stainless steel.
- Attach the mounting frame to the anchors.
- Position the panels onto the mounting frame. And, clamp them in place in the correct position.
- Then, feed the DC electrical cables from the panels, alongside the frame to the anchors, and into the loft space. It’s standard practice for the cables to be hidden behind the panels as much as possible.
- Next, you need an inverter connected to the mains electricity supply at a convenient location within the house.
- Then, the installer will fit a separate consumer unit and a generation meter next to the existing consumer unit.
- When everything is connected, the installation engineer checks the system to ensure everything operates correctly.
If you’ve used an MCS installer, you’ll then receive an MCS certificate.
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Benefits of Solar Power
Solar–powered technology has many advantages, that go beyond domestic solar electricity generation. But, for now, let’s narrow the benefits down to specifically solar power for home use.
Renewable energy source
Solar power is a completely renewable energy source. It requires no fuel except for the sun and can generate electricity even on cloudy days. The technology can be used in every country in the world and is available every day. Solar energy can even be stored for use at night.
Lower electricity bills
Your PV system generates electricity which will replace some of the mains power you buy from your electricity provider. The reduction in mains energy usage will depend on the size and efficiency of your solar panels and how much electricity you use. Furthermore, not only will you reduce your energy bills, but you also have the potential to earn money by exporting power to the National Grid if you generate more power than you use.
Low maintenance costs
Solar panels don’t contain any moving parts and they’re all solid–state electronics. Therefore, they need very little maintenance. As long as you keep the glass panel clean and free from dust, soot and other debris, they should be okay. You’ll probably need to clean the panels a couple of times a year. Typically after winter’s finished and before the following winter starts.
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You can clean them yourself if you feel capable of climbing on the roof, But, as specialist companies charge between £25 and £35 to do the job. It might be better to leave it to them.
Reputable solar panel manufacturers give warranties of around 25 years, and as there are no moving parts, you shouldn’t have any problems. However, the only thing that might need changing is the inverter which will last for between 5 and 10 years.
Supplements other sustainable energy generators
When you need electricity to power other sustainable energy sources, solar power is ideal. For example, When installing an air source heat pump, you need electricity to power the pump. Air source heat pumps extract heat energy from the surrounding air. They use a system of heat exchangers to transfer the energy into your home to heat domestic hot water and central heating. You can use solar energy to power the pumps in the heat exchangers and the central heating. This effectively means that your hot water and central heating are completely free.
Moving on, solar panels will also supplement ground-source heat pumps, solar thermal panels and wind turbines too. Either by powering pumps and other equipment or by each one feeding energy into a thermal store.
And what’s more, all these sustainable energy methods qualify for financial help when you sell excess energy to the electricity suppliers. We’ll talk about this later.
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Saving Money With Solar Panels
We’ve already mentioned how solar panels can reduce your electricity bills. But, we haven’t mentioned how it will also cut your carbon footprint by using purely sustainable solar energy. Typically, a standard domestic solar PV system can also prevent a substantial amount of carbon dioxide being pumped into the air from fossil fuels.
Let’s consider these two benefits in more detail.
According to the Energy Saving Trust, the average domestic photovoltaic energy system totals about 3.5kWp, which will cost around £4800 to buy (including VAT, charged at 5%). In the south of England, this size system will generate about 3700kWh per annum of electricity. It also saves about 1 tonne of carbon dioxide every year.
Assume we live in Scotland and use the same size PV system. We will generate about £2850kWh electricity per annum and save about 0.8 tonnes of carbon dioxide each year.
This is good for us, and good for helping the Government comply with its, environmental obligations.
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The Feed-in Tariff Scheme
Unfortunately, this has closed to new solar PV applications in March 2019. But, for those who have already joined the scheme, it will last for the remainder of their contract (usually 20 years). At its height, the Feed-in Tariff (FIT) paid households for generating energy and exporting it into the Grid. The FIT scheme encouraged people to install solar PV systems with the incentive of extra remuneration from the government. Hopefully, this scheme has served its purpose and people now want to install solar for the sake of environmental benefits.
The next scheme to take its place is the Smart Expert Guarantee.
Smart Export Guarantee (SEG)
This came into effect on 1st January 2020. The idea is that energy suppliers, not the government, must pay domestic renewable energy generators for the electricity they export to the National Grid. It’s not only solar that benefits from this scheme. All small scale, low carbon generation methods such as wind, and hydroelectric are included too.
The payment rate varies with the energy supplier. The old FIT export tariff used to be 5.24p/kWh of renewable energy produced. Although the government hasn’t set a rate for energy providers to buy the electricity, some companies are already offering Smart Export Guarantee rates of more than 5.24p/kWh. As this scheme starts to gain momentum, we hope that energy companies will compete amongst themselves and offer ever higher SEG rates.
Under this system, households earning money with solar panels can be paid by either a fixed or a flexible rate.
- A fixed–rate SEG is a fixed rate paid for every kWh of renewable energy exported to the Grid.
- A flexible SEG rate pays varying rates depending on the time of day. For example, there is a higher demand for electricity in the evening so you would be paid more at this time of the day compared to the energy supplied in the morning.
To be eligible for SEG payments, you must live in the UK, be generating renewable energy at home using one of the specified methods, and have an MCS certified installation.
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But is SEG worth it?
At present, the best rate, offered by Social Energy is 5.6p/kWh. The next favourable rates are from Octopus Energy and E.On who offer 5.5p/kWh. The worst at present are Utility warehouse who pay 0.5p/kWh. Luckily you don’t have to sell your electricity to the company that supplies you. So, hopefully, there will be plenty of competition over the next few years.
The following table outlines how much annual savings can be made in different parts of the country. These figures assume you’re out of the house until 4 pm each day and so export all your generated power.
| Location | With SEG | Without SEG |
|---|---|---|
| London, SE England | £240 | £120 |
| Aberystwyth, NW Wales | £220 | £115 |
| Manchester, NW England | £215 | £115 |
| Stirling, Scotland | £195 | £110 |
Sources: solar installation payback & solar panels electricity
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What is a PV Diverter?
A PV, or solar power, diverter monitors the
- Amount of energy being generated by your system.
- And, the amount being consumed by your house.
It will only divert energy to the Grid if there is a surplus amount of electricity being generated.
The benefit of this clever little gadget is that it assumes everything in your home takes priority of exporting the power. So, for example, it will make sure your hot water immersion heater has enough energy before selling on any excess.
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How Does a Solar Panel Work?
Okay, let’s do the science part now. A solar panel is made up of many solar PV cells (a.k.a. photovoltaic or PV cells). Photons of light knock electrons away from atoms inside the cells, producing a cloud of electrons. Inside the cells, there are conductive metal plates that collect the electrons and push them into wires where they can flow like any other electric current. At this stage, the current is ‘DC’ or Direct Current’. To be useful in a domestic situation we have to convert the Direct Current obtained from the PV systems into Alternating Current (AC) using an ‘inverter’. When we have AC we can power all the appliances within our homes and export electricity to the Grid.
Energy Storage: Solar Battery Technology
Storing the energy you generate is a good idea and can save you money. Especially, if you don’t intend exporting energy to the Grid. All PV systems generate the maximum amount of electricity around midday when the sun is at its strongest. Unfortunately, this is the time of day when most people are at work and not using the generated electricity. Using a solar battery allows you to store the energy for use later in the day when you’re home.
But are they cost–effective?
Typical costs of solar batteries in the UK lie between £1200 and £6000. Also, the typical lifespan of a solar battery can be from 5 to 15 years. This means that the solar battery might have to be replaced more than once over the typical lifespan of your solar panels (15 to 30 years). As we can see, a solar battery can be expensive. But, the amount of energy you save over their lifetime will more than pay for their initial capital cost.
You can buy solar batteries from many sources including most energy suppliers.
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Online calculator
There is a particularly useful calculator on Great Home to help you work out how much savings you will receive from using a solar battery. This calculator also incorporates any payments due from SEG tariffs.
The following table itemises the various pieces of data used along with the projected savings on your electricity bill. And, as a bonus calculates the payback time for your investment.
| Input Data | Energy used | 3500kWh |
| Solar energy generation | 3400kWh | |
| Energy purchaced from the Grid | 960.4kWh | |
| Losses | 134.6kWh | |
| Energy exported (SEG) | 719.0kWh | |
| Battery Charge change | 6.6kWh | |
| Output Data | Bill without solar battery | £595 |
| Bill savings | -£431.74 | |
| Export payments (SEG) | -£39.55 (5.50p per kWh) | |
| Total annual benefit | -£471.28 | |
| New electricity bill | £123.72 | |
| Payback time | 30.8 years | |
| Total investment | £14,500 | |
| Battery utilisation | 61.8% |
UK Regulation & Planning Permission
Generally, installing solar panels on your land comes under the category of ‘permitted development’. So there should be no need to apply for Planning Permission. However, you must comply with many important conditions to be put in this category. And, these are listed on these Planning Portal pages.
Installation of solar panels comes under the scope of the UK Building Regulations. Generally,
- The existing roof must be able to support the additional load.
- The electrical installation must comply with the current electrical regulations.
- Use a competent installer. You can find one by using the search tool on the UK Government website.
- Alternatively, a competent installer will be certified with the MCS.
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Solar Panel FAQ
How long do solar panels last?
The solar panel’s lifespan depends on the manufacturer. But, usually, it’s assumed to be between 25 to 30 years.
Can I put solar panels on my shed roof?
Yes, as long as the roof is strong enough to withstand the extra load. Contact the manufacturer of the equipment to find out the specifications of the panels. And, ask advice from an MCS certified installer.
Can I run my entire house on solar power?
The answer to this depends on the size of the PV system and how much electricity you intend to use across the year. Generally, the average home needs a 4kWp solar panel system to produce enough electricity. You will also have to incorporate a solar battery into your system. Otherwise, energy will be going to waste during the day when you are at work and not consuming. And, you won’t have any electricity at night.
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Do solar panels work at night?
The simple answer is no!
Solar panels need sunlight to generate electricity. And, if the sun has set, you won’t generate electricity. However, you can install solar batteries to save excess energy generated during the daytime, for use at night.
How long should a solar inverter last?
As long as you maintain the inverter according to the manufacturer’s instructions, your inverter should last from 5 to 10 years.
What are the disadvantages of solar energy?
Major disadvantages are as follows:
- Solar panels have a relatively high initial capital cost.
- Although you can collect solar energy while it’s cloudy or raining, the efficiency will drop. Furthermore, you might end up harvesting about half the amount that you would collect on a sunny day.
- Solar storage batteries are expensive.
- Solar panels take up a lot of space.
- Although they harvest 100% renewable energy. Manufacturing solar panels can produce pollutants.
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Do solar panels melt the snow?
Yes. Silicon PV cells appear dark to absorb as much energy as possible from sunlight. Once a small portion of a panel warms up from the sun, the heat will spread, slowly warming the remainder of the panel. Eventually, the entire panel will be clear of snow. It’s not unusual to see a roof completely covered in snow, whereas the panels are snow-free.
Find Solar Panel Installers Near You
If you can afford the capital outlay of purchasing solar panels and having them installed, they are a worthwhile investment. However, they aren’t something that you can install as a DIY project. If you want to find out how much a system of solar panel costs to buy and install, complete the form on this page. You’ll then receive 3 or 4 quotes from qualified installers near you.
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