Why Homebuilders are Choosing Solar Panels – We Speak to an Industry Expert about the Benefits of Installing Solar Technology
For property developers, fitting solar panels on the roofs of their new homes has become a relatively common practice. And it’s a wise move from the industry, as, despite not being a mandatory measure set out by the government, it is still an important selling point for homebuyers. ‘A new study conducted by E.ON Energy found that 89% of prospective buyers want sustainable homes that are kind to the planet,’ reports Country Living, going on to reveal that, ‘80% said they'd prefer solar panels over having a garden.’
In addition to providing the features that buyers want, installing solar panels also helps developers meet the energy efficient standards and Standard Assessment Procedure (SAP) ratings, to demonstrate compliance with Part L of the Building Regulations and produce a good rating on the property’s Energy Performance Certificate (EPC).
As the UK transitions towards the 2025 Future Homes and Buildings Standards, where new homes and buildings will be ‘zero carbon ready,’ the expectation is that heat pumps will become the primary heating technology for newbuilds, alongside other green technologies, such as solar panels.
However, unlike solar panels and wind turbines, which are energy generators, heat pumps are energy consumers. Therefore, incorporating solar technology into roof spaces is often a simple, natural decision from both a technical and commercial viewpoint.
In this blog, we will be discussing the use of solar technologies on newbuild homes through a series of questions with industry expert, Keven Feeney. Feeney has over 20 years’ experience developing, manufacturing and installing energy efficient ventilation equipment, as CEO of leading ventilation company, VES.
In 2023, Feeney made the switch to develop his own business, EVR, with friend and business business partner, Scott Taggart. Their passion for energy savings and energy efficiency drives them to focus on providing full building solutions, including lighting, renewables, green power, storage, and also ventilation.
‘Green energy should be accessible for all,’ says Feeney.
Classic Folios: Why are Solar Panels Regularly Chosen?
Kevin Feeney: The energy efficiency of new homes has dramatically improved through the tightening of the emissions target. The average new build designed just five years ago would be highly unlikely to pass the regulations today.
To decarbonize new homes, the focus is on improving heating, hot water systems and reducing heat waste, by ensuring the fabric of the budling is well insulated, using highly insulated windows and doors, the use of zonal heating, and with load and weather compensators to reduce waste. Ensuring the building is sealed reduces heat waste, while limiting thermal bridging through the transfer of heat and losses through junctions with external walls.
However, the risk that comes with implementing very high-quality building fabric materials and building standards, is that this raises the overall costs of the build, which will be a cost naturally passed down to the homebuyer.
As building fabric costs continue to rise, along with planning constraints and supply chain volatility, the use of renewable energy solutions is a key factor in passing the SAP, as this assessment takes into consideration the energy generation from renewables.
Solar panels also have the practical benefit of flexibility in their design, only governed by the available roof space and budgets. The final design of the solar panels can be adjusted simply, right up until the roof tiles are to be fitted. This gives the developer flexibility as the scheme unfolds, so any other site-wide changes that impact the SAP calculations can be accommodated by the design of the solar panels.
Solar PV panels offer the additional advantages of saving on tiles when the design is incorporated into the roof, while demonstrating a very visual commitment to green technology and the environment.
The installation of solar PV panels is relatively easy, provides clean renewables energy for the future homeowner and can improve the property SAP rating by up to 15 points.
CF: What are the Options for Homebuilders when Installing Solar PV Panels?
KF: Generally, there are three types of solar PV panels that are used in newbuilds, all with their advantages and disadvantages.
Solar Tiles
Although solar tiles can offer the most aesthetically pleasing installation, almost blending seamlessly into the roof and tiles, the technology is relatively new and, at present, not widely adopted. This newness also makes them considerably more expensive. They are not widely available, with a limited installer base compared to conventional solar cells.
At present, they are in most cases less efficient, so require more area of roof space (m2) to provide the same level of power output. As Build Regulations continue to tighten, it raises questions around whether the technology can be scaled widely across new build schemes. If the increase in individual cell costs is compared with the need for increase in space area, we can see schemes costing up to five times more than the conventional solar cell counterpart.
On-Roof
Solar panels are not the preferred option for new builds but are the most widely recognized solar roofing system in the UK, as we continue to add solar systems to our existing housing stock. This system is fixed to a mounting hook that replaces an existing roof tile; the rails are fixed to the roof hook to provide a structure for the solar panels to be secured onto.
These panels are simple to install, very effective for existing roof structures, but are not the most aesthetically pleasing due to the fact they are raised above the roof by up to 100mm.
In-Roof
These solar systems offer the most advantages for developers in the new build market. These systems become part of the roof, so the solar panels are mounted on the roof battens in place of tiles.
The benefits of this are that they offer some cost savings in tiles; they sit flush and blend in seamlessly with the roof, providing efficient energy production; and they are cost effective due to the large global market.
Adding an in-roof system during the build is easy and can be completed in coordination with the other trades on site. Their speed and flexibility make in-roof solar systems an invaluable solution for developers to help them meet energy reduction requirements.
In-roof solar panel installation carried out by EVR Limited
CF: What Should Developers Consider When Comparing Bespoke Solar Cells with In-roof Frames?
KF: Broadly speaking, there are two ways of achieving an in-roof solar system.
One method is to use a bespoke system, where the solar panel itself is made specifically for both the electrical generation and the roof mounting system, for example, from Viridian or other solar tile providers, as mentioned above.
Another is the use of a standard solar panel using an in-roof frame, such as, the GSE System.
The Viridian bespoke system offers a robust solution, achieving the highest fire rating, expectational wind resistance, and works with both slate and tile roof options.
The solution is compact, and has a sleek, patented design with invisible clamps for uncluttered aesthetics.
The GSE and solar cell combination is the most technically sound and commercially effective solution for the new build market.
This method provides comparable generation efficiencies and achieves the highest standards of fire rating and wind resistance, with comparable aesthetics to their bespoke counterpart.
This method offers both short and long-term advantages, as they are not product specified, giving the developer flexibility in the approach to both the design and the commercial aspect of the solar systems.
The solutions can be mixed and matched with a number of fully tested solar PV cells, with manufacturers providing a wider choice from the supply chain and having the ability to neutralize any future supply chain volatility. This is, of course, vital to keeping the projects onsite running smoothly.
As we approach the tightening of energy performance ratings and schemes being developed months and years in advance, the ability to have flexibility in the design and installation is paramount, providing the opportunity to take advantage of new cell technology as and when it comes to the market, while offering high levels of competitiveness as the solar PV system is not specified by one single manufacturer.
CF: Are There any Product Quality or Safety Concerns?
KF: As solar PV is one of the fastest growing, most reliable, and most adaptable forms of renewable energy technology available, it will likely remain the preferred choice for the new home building industry, and installed in coordination with the roof installation.
Having solar PV cells in replacement of tiles, however, poses an increased risk to the property. The incidence of fires involving PV systems is very low, but the addition of a solar PV system which is not designed using high quality products, or installed and commissioned correctly – like any electrical service – adds an overall fire risk.
Historic findings from a technical report published by the IEC in February 2021 – IEC TR 63226:2020 - reviewed fire risk related to photovoltaic (PV) systems on buildings. The report found that the primary causes of solar PV system fires are installation, product defects and system design issues, all of which contribute to 72% of the causal factors for fire.
The risk of fire is dramatically reduced by using Tier 1 products provided by established supply chain manufacturers, who are regularly inspected and meet local UK regulations and standards.
It is important to ensure the work is carried out by approved installers registered with the Microgeneration Certification Scheme (MCS), who deliver designs and installations to meet MIS300, and who are regularly inspected on their quality standards to ensure the technology is fit for purpose. Using an MCS-registered installer provides security as the workmanship is backed by the MCS’s 5-year Insurance Back Guarantee.
An analogous UK study, undertaken in 2017 by the Building Research Establishment (BRE), investigated the solar PV components most likely to develop faults that led to a fire incident, and outlined the most critical component failures to be:
Ensuring the quality of the electrical installation and the use of Tier 1 products, helps reduce the risks associated with solar PV cells, inverters, DC cables, isolators and connectors. Further risks are mitigated by the off-site manufacturing of the electrical boards, as this allows for a more thorough off-site quality inspection process.
However, in all installations, there are a number of electrical connections that cannot be made and tested in the factory, and therefore need to be carried out on site. The dangers of DC power are recognised and it is good practice to include supplementary DC protection in the form of Arc Detection and containment. Electric arcing is very energetic and results in incredibly high temperatures - far in excess of the melting temperature of metals, and one of the biggest sources of electrical fires in integrated solar roof systems.
The selection of the inverter requires careful consideration, to ensure it includes in-built Arc Fault Detection as standard, which will help to prevent fires by detecting any electrical arcing between cables.
Supplementary to this, is the installation of Arc Containment Boxes, where the final electrical connections made on-site are housed within a ceramic, fully sealed box to prevent fire from spreading. The Arc Box (trademark) enclosure simply snaps around a DC connector to ensure that if an electrical Arc occurs, it is safely contained and doesn’t spread to combustible materials in or around the solar installation.
Independently tested by KIWA, and in accordance with NEN 6063, this is a very low-cost supplementary improvement that can greatly reduce the risk of Arc related fires.
CF: Are There any System Sizing Considerations or Restrictions?
KF: There are a number of considerations regarding the size of the solar panel system. These are predominately regarding the PV kW – the power rating – of the system, as it is designed to meet the SAP calculations and, consequently, the energy standards of the property and current Building Regulations in order to achieve a pass status by building control.
Generally, solar PV system size in the newbuild market is smaller than those within the refurbishment market, as the aim is to meet the SAP rating assessment, as opposed to targeting the future occupiers needs.
The restrictions to the size of the PV system are two-fold, the more obvious being the available roof space and the physical size of the system panels to be safely installed to meet the most up to date MCS standards. There is another restriction imposed on systems by the Distribution Network Operator (DNO).
Developers of new homes will have already agreed the necessary utilities needed for the site and the local DNO will issue the relevant property MPAN numbers for individual plot electrical input references.
Under current legislation, the DNO imposes restrictions to the size of the generation system, which will be connected to their grid. This is to protect the local infrastructure and ensure the possible power flows can be handled without causing damage to the local electricity supply. It is often reported than this limitation is 3.68kW and therefore it is not possible to install solar PV panels above this size – this is false and incorrect.
There are two avenues to notify and document the connection of solar PV generating equipment, which must be completed by competent persons, and are necessary for valid building and home insurances, along with the ability to connect with your utility provider. The G98 has been established for domestic systems which fall under the 3.68kW capacity, and the G99 which is suitable for installations above 3.68kW.
Again, wrongly interpreted is the 3.68kW capacity. This is the registered capacity of the connected device to the grid network and not the Solar PV System size. For example, it is quite feasible for a 4.2kW system that has an East/West orientation to be installed with a 3.68kW inverter, as the capacity of the solar never reaches the maximum input of the inverter. Therefore, the size of the solar PV system is in fact larger than 3.68kW, but the inverter, the part connecting to the grid, still complies with the requirements of G98 and therefore can be installed as a ‘connect and notify’ installation.
Current new build trends don’t tend to use larger solar PV installations over 3.68kW. However, with the drivers in the homebuyer market seeking more sustainable properties, combined with the increasing standards for higher energy efficient buildings, and the increase in electrical usage due to the introduction of heat pumps, it is highly likely that we’ll see larger solar PV systems installed to support this need.
The average UK household electrical use of 3,509kWh per year is already well beyond the solar PV systems often being installed in new builds, and those homeowners with heat pumps, hot tubs and electric vehicles are already consuming energy at rates well above the average. They could be using anywhere between 5,000kWh up to 7,500kWh per year, even in relatively compact three-bedroom properties.
The DNO standards already cater well for larger generation systems, with the introduction of the Fast Track G99 process, whereby the energy generating device, the inverter, can be increased to 7.36kW per phase, as long as the Export Capacity is limited to 3.68kW.
This paves the way to easily increase solar PV system sizes beyond the current convention, perhaps up to as much as 11-12kW systems, carefully designed and suitably orientated, giving the homeowner the ability to generate and store a significant portion of their home energy and offsetting the expensive peak rate energy.
The Fast Track process from the DNO allows for larger systems to be installed and remain as a ‘connect and notify’ installation. A well established and experienced MCS certified installer will help generate designs to meet energy needs now and in the future, while taking care of the DNO Connection on behalf of the developer and future homeowner.
So, the only real constraints are roof size and budget.
CF: What are the Reasons for Customer Disappointment?
KF: As an approved installer of Solar PV systems, we regularly speak with new homeowners who are disappointed in the size of the solar system installed on their new property. They often wish more generating power was available to help reduce their energy bills. However, the solar PV designs developers often install are relatively small as they aim to achieve the necessary SAP ratings for Building Standards.
In addition to wishing more solar panels were installed, homebuyers often complain that their systems are not suitable for battery storage. The inverters installed match the solar requirement and are therefore rarely of the hybrid type required for the connection of batteries in the future.
For property developers, cost control is vital for the continued provision of affordable homes. However, there is more we can do to future-proof properties and cater for the ever-growing needs to control energy usage. A simple, cost-effective improvement to ensure the longevity of properties is the inclusion of data cable. This will reduce some of the future installation costs when upgrading to a hybrid system with battery storage, providing the necessary information to automatically manage energy.
It is also important to work closely with developers so that we can provide future homebuyers with the customisation options similar to those in place for their kitchens, bathrooms and garden landscaping. We believe it is important to provide choices to prospective buyers around their energy generating systems, and to give them the ability to increase the size of their solar PV system, and/or the inclusion of batteries to capture the surplus solar energy and force charging at low utility rates, alongside other energy accessories like EV car chargers and energy diverters for the hot water.
Working in collaboration with the developer’s sales team provides the future buyer with the level of customization necessary to meet their individual needs, without distracting the developer from the objective of delivering high quality, energy efficient, affordable homes.
An interview with Kevin Feeney, of EVR Limited.
EVR (which stands for Electrical Ventilation Renewables Limited) has been operating in the energy sector for many years and has been fully complaint with the Micro Generation Certification scheme (MCS) for over 12 years. Their mission is to deliver support for customers to ‘be energy smart' by reducing energy consumption, helping them generate and store energy, use energy efficiently while improving their carbon footprint, and building and home operation. They use the latest technology to develop solutions to meet the needs of their customers now and in the future. You can find out more about their services and arrange a consultation at: www.evrltd.co.uk