Plug in solar panels are now legal to buy and use in the UK, giving more households an opportunity to generate some of their own electricity. However, if you have seen these lower cost systems advertised, you may be wondering: are plug in solar panels safe, and how do they compare with professionally installed rooftop solar?
For some households, plug in solar could be a useful option. In particular, it may appeal to renters, people living in flats or those without suitable roof space. However, homeowners with a suitable roof should understand the significant differences between an 800W plug in system and a professionally designed rooftop solar PV installation.
Safety is also an important consideration. Although compliant plug in systems can operate safely, connecting generation equipment to your home is very different from plugging in an ordinary appliance.
What Are Plug In Solar Panels?
Plug in solar systems allow a small solar PV system to connect to a standard UK mains socket.
The Government currently limits each system to a maximum output of 800W. According to Government estimates, this could provide up to 20% of an average home’s electricity use and potentially save a household up to £110 per year.
However, actual savings will depend on several factors. These include where the panels are positioned, shading, household electricity consumption and how much generated electricity can be used at the time it is produced.
Plug in panels can be positioned on balconies, external walls, outbuildings or suitable areas at ground level. Therefore, they could make solar accessible to people who previously had few practical options.
For a homeowner with suitable roof space, however, it is important to understand that plug in solar and professionally installed rooftop solar are very different propositions.
Plug In Solar vs Professionally Installed Rooftop Solar
The individual solar cells are not necessarily less efficient simply because they form part of a plug in system. The major limitation is the size and capability of the overall system.
Here is where the differences become much clearer.
| Plug in solar | Professionally installed rooftop solar | |
|---|---|---|
| Maximum system output | Up to 800W | Designed and sized around the property and requirements |
| Potential electricity contribution | Government says up to 20% of average home electricity use | A larger array can make a substantially greater contribution, depending on system size, property and consumption |
| Government quoted potential saving | Up to £110 per year | Up to £480 per year for rooftop solar |
| Panel positioning | Balcony, wall, outbuilding or ground level, depending on the product | Roof professionally assessed for orientation, pitch, shading and available space |
| Battery storage | Not included within the current plug in solar framework | Can be designed alongside suitable battery storage |
| Electrical assessment | Consumer needs to ensure the existing installation is suitable | Electrical installation assessed as part of professional design and installation |
| Consumer unit and protection | Homeowner may need an electrician to establish whether existing protection is suitable | Protection requirements considered by the installer |
| System design | Small standardised system | Designed around the individual property and energy requirements |
| MCS certification | Not the same as an MCS certified rooftop installation | Can be installed and certified through an MCS certified contractor |
| Export options | Primarily intended to reduce grid consumption while generating | Eligible installations can potentially receive SEG payments for measured exports |
| Warranties and aftercare | Dependent on the product and retailer | Installation, equipment warranties and aftercare provided according to installer and manufacturer terms |
The Government figures above are estimates, not guaranteed savings. Actual performance and savings will vary between properties.
However, they demonstrate an important point. Plug in solar is designed as a small scale solution. Professionally installed rooftop solar can be designed as a much larger home energy system.
Are Plug In Solar Panels Safe?
This deserves a balanced answer.
The Government commissioned an independent electrical safety study before introducing plug in solar. It concluded that plug in solar systems could operate safely under the conditions tested, with appropriate product requirements.
However, the study also identified variations in product performance. Therefore, product quality should not be assumed to be identical across everything available on the market.
Electrical Safety First has also raised additional concerns about how plug in solar interacts with existing domestic electrical installations.
This is particularly important because the word “plug in” can make the process sound much simpler electrically than it actually is.
Your Consumer Unit Matters More Than You Might Think
Before connecting solar generation to your home, you need to consider the electrical installation that sits behind the socket.
For example, what type of consumer unit do you have?
What type of RCD protects the circuit?
Is that RCD suitable for bidirectional current?
What condition is the circuit in?
Has the installation been altered previously?
Is the socket and circuit suitable for this particular use?
Most homeowners understandably will not know the answers to these questions.
An RCD is designed to provide protection against certain electrical faults. However, there are different types of RCD.
Electrical Safety First currently recommends at least a Type A bidirectional RCD on circuits intended for use with plug in solar. It also advises that homes with Type AC RCDs should not use plug in solar without first upgrading the relevant protection.
Type AC RCDs are particularly relevant because they can still be found in older electrical installations.
Therefore, buying a compliant solar kit does not automatically confirm that the electrical installation inside your home is suitable for it.
Why Does Electricity Flow Matter?
Normally, electricity is supplied from your consumer unit through the circuits in your home to appliances and other loads.
Plug in solar introduces another source of electricity onto an existing circuit.
Consequently, electricians need to consider how this additional source interacts with circuit protection and existing wiring.
Electrical Safety First has highlighted a particular concern with ring final circuits.
A ring circuit normally distributes load through both sides of the ring. However, introducing solar generation at another point on that circuit can alter how current flows.
Under certain conditions, Electrical Safety First warns that this could result in excessive current through part of the circuit. In turn, this creates the potential for localised cable overheating or fire risk without the circuit breaker necessarily detecting the combined loading as someone might expect.
That does not mean plugging in a compliant solar system will automatically cause a fire.
However, it demonstrates why connecting electricity generation to an existing circuit deserves more consideration than simply asking whether the plug fits the socket.
Fire Safety Should Never Be an Afterthought
Solar PV itself is established technology, and professionally installed solar systems operate safely across millions of properties.
However, all electrical installations need suitable design, protection and equipment.
London Fire Brigade advises consumers using plug in solar not to connect systems through extension leads, cable reels, adaptors or overloaded sockets. It warns that overloaded electrical connections can overheat and cause fires.
Cables also need protection from physical damage.
Additionally, Electrical Safety First recommends that households have their electrical installation assessed by a competent electrician registered with a competent person scheme before buying or using plug in solar, particularly in older properties or where the condition of the installation is unknown.
This is an important point for homeowners.
Without an electrical assessment, how do you know whether your consumer unit, RCD and existing circuit are appropriate for connecting generation equipment?
The equipment you buy could meet the required product specification while another part of your existing electrical installation still requires attention.
Why Professional Rooftop Solar Is Different
When you choose professionally installed rooftop solar, you are not simply paying someone to put panels on a roof.
The design process considers the entire installation.
A professional solar installer can assess your roof, electrical installation, energy consumption and the equipment required to create an appropriate system.
This includes considering panel orientation and pitch.
Shading from trees, chimneys, neighbouring buildings and different roof elevations can affect generation. Therefore, panel positioning should form part of the system design rather than simply placing panels wherever they physically fit.
The roof structure must also be considered. MCS requirements include checking that a roof structure can withstand the loads imposed by a solar PV system.
Furthermore, the installation must maintain the structural integrity and weather tightness of the building.
These are details that homeowners do not necessarily see, but they are an important part of a professional solar installation.
Why MCS Certification Matters
MCS certification is particularly important when comparing professionally installed solar with a consumer plug in product.
MCS sets standards covering the design, installation and commissioning of small scale renewable technologies.
An MCS certified contractor must demonstrate the capability to design, install, commission and hand over solar PV systems in accordance with relevant requirements.
For homeowners, this provides an established framework around the installation.
It also means you receive documentation relating to the system rather than simply purchasing a piece of electrical equipment and connecting it yourself.
At West Coast Electrical & Renewables, our solar installations consider the property as a complete system. That includes the solar panels, inverter, electrical installation, consumer unit, protection, roof, expected generation and the household’s electricity requirements.
A Professionally Designed System Can Do Much More
For homeowners with suitable roof space, one of the biggest advantages of professional solar is the ability to design a system around how the home actually uses electricity.
Rather than being restricted to 800W, a rooftop array can contain multiple panels and provide considerably greater installed capacity.
Battery storage can also be incorporated where appropriate.
This means surplus solar generation can potentially be stored for use later rather than all of the benefit depending on electricity being consumed at the same time as generation.
Depending on the household, system and electricity tariff, battery storage can also provide other options, such as charging at cheaper overnight electricity rates for later use.
The correct approach will vary from home to home, which is why system design matters.
What About Selling Electricity Back to the Grid?
This is another area where professionally installed rooftop solar can offer greater opportunities.
Plug in solar is primarily designed to reduce the amount of electricity a household imports while the panels are generating.
With professionally installed solar, eligible households can potentially receive payments for measured electricity exported to the grid through the Smart Export Guarantee.
Eligibility requirements apply, and export tariffs vary between electricity suppliers.
This gives a professionally designed solar and battery system considerably more flexibility around how generated electricity is used, stored or exported.
Warranties, Documentation and Aftercare
Solar panels should remain on your property for many years. Therefore, the company and equipment behind the installation matter.
A professional solar installation can include manufacturer warranties for panels, inverters and batteries, alongside applicable workmanship protection and installer aftercare.
You also have someone to contact if you have questions about system performance.
If generation changes unexpectedly, an inverter reports a fault or you simply do not understand what the monitoring app is showing, having an experienced installer behind the system provides valuable support.
For many homeowners, that peace of mind is just as important as the equipment itself.
Who Are Plug In Solar Panels Really For?
Plug in solar could be a great development for the right person.
If you rent, live in a flat, have a balcony but no usable roof, or simply cannot have conventional rooftop solar installed, an 800W plug in system could allow you to generate electricity that previously was not available to you.
That is a positive step.
However, if you own a house with suitable roof space, we would recommend comparing the limitations of plug in solar with what a professionally designed rooftop system could provide before making a decision.
An 800W plug in system and a professionally installed solar PV array are not really competing versions of the same product.
They serve different purposes.
For homeowners who want solar to make a meaningful contribution to their electricity consumption, professionally installed rooftop solar offers greater generating capacity, professional electrical assessment, optimised panel positioning, battery storage options, potential export payments, MCS certification, warranties and ongoing support.
Most importantly, you are not left to determine for yourself whether your existing consumer unit, RCD protection, wiring and electrical circuits are suitable for connecting generation equipment.
Considering Solar for Your Home?
If you have suitable roof space and are considering solar PV, West Coast Electrical & Renewables can assess your property and design a system around your roof, electrical installation and household energy requirements.
Our team can advise on solar PV, battery storage and the electrical work required to create a professionally designed home energy system.
